Service Manual Logamax Plus GB142 (USA/CA) En 72149400 07 Instructions 12.2011 US

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Servicing instructions

Condensing gas boiler

WARNING!
Improper installation, adjustment, alteration, service or maintenance can
cause injury, loss of life or property damage. Refer to this manual. For
assistance or additional information consult a qualified installer, service
agency or the gas supplier.

Warning: If the information in these instructions is
not followed exactly, a fire or explosion may result
causing property damage, personal injury or death.
– Do not store or use gasoline or other flammable vapors and liquids in
the vicinity of this or any other boiler.

– What to do if you smell gas
• Do not try to light any boiler
• Do not touch any electrical switch; do not use any phone in your
building.
• Immediately call your gas supplier from a neighbor’s phone. Follow
the gas supplier’s instructions.
• If you cannot reach your gas supplier, call the fire department.
– Installation and service must be performed by a qualified

installer, service agency or the gas supplier.

Notice:

7214 9400 (11/2011) US/CA

This manual must be retained for future reference.

Logamax plus
GB142-24/30/45/60

For installers
Please read thoroughly
before servicing

Preface
About these instructions
These Servicing Instructions contain important information to
diagnose and resolve issues concerning the GB142 boiler with
capacities 24, 30, 45 and 60 kW.
These Servicing Instructions are intended for specialist installers, who have the necessary training and experience for working
on heating and gas systems.

Subject to technical changes!
Slight changes may be made to the illustrations, process steps
and technical data as a result of our policy of continuous
improvement.

Updating of documentation
Please contact us if you have any suggestions for improvements
or corrections.

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Contents
8.1.7

1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8

Safety and general instructions
Designated use
Hazard definitions
The following instructions must be observed
Observe these instructions for heating
system water
Tools, materials and additional equipment
Inspection
Disposal
Abbreviations

Regulations and guidelines

8.1.26
8.1.27
8.1.28
8.1.29
8.1.30
8.1.31
8.1.32
8.1.33
8.1.34
8.1.35

Checking the supply/return/safety/hot-water
temperature sensors
Checking the hot-water temperature sensor
Checking the supply/return/safety sensors cable
Checking the hot surface ignitor; control
Checking the hot surface ignitor; resistance
Checking the hot surface ignitor; supply cord
Testing the ionization current
Checking the ionization electrode; cable
Checking the ionization electrode;
replace if necessary
Checking the gas control valve;
cable connections
Checking the gas control valve;
cable connection between gas control valve
and UBA 3 installation base
Ohming out the gas control valve
Replacing the gas control valve
Checking the control unit; connections
to the boiler
Bleed the gas supply pipe
Measuring the inlet gas pressure
(flow pressure)
Measure and adjust the gas/air ratio
Measuring the carbon monoxide content (CO)
Transformer; replacing
Automatic air purging system; replacing
Burner; replacing
Sight glass; replacing
Condensate trap; replacing
Pressure sensor; replacing
Heat exchanger; replacing
UBA 3; replacing

107
108
109
109
111
113
115
116
116
117
125

Appendix

126

Spare parts

128

4
4
4
4
5
5
5
5
6

8.1.9
8.1.10
8.1.11
8.1.12
8.1.13
8.1.15
8.1.16
8.1.17
8.1.18
8.1.20

Product description

8.1.21
8.1.22
8.1.23

Operation

4.1
4.1.1
4.2
4.2.1
4.2.2
4.2.3
4.2.4

Operating the BC10 basic controller
General
Menu structure of the BC10 basic controller
"Flue gas test" menu
"Service Mode" menu
"Manual Operation" menu
"Adjustments" menu

9
9
9
10
11
12
12

8.1.24
8.1.25

Function

5.1
5.2

General
Structure diagram "Function"

14
15

Symptoms

6.1.1
6.1.3

6.2

General
Display codes on the display of the BC10
basic controller
LED on the UBA 3

20
26

Diagnosis

7.1
7.2

Faults without a fault code
Faults with a fault code

27
46

Actions

8.1

Testing, measuring, adjusting and replacing
various components
Checking the UBA 3 fuse; replace if necessary
External connection board fuse
Checking the fan unit; 120 VAC control
Checking the fan unit; supply cord (120V AC)
Checking the fan unit; tacho cable
Replacing the fan unit

84
84
85
86
87
88
88

8.1.1
8.1.2
8.1.3
8.1.4
8.1.5
8.1.6

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

89
91
92
92
93
93
95
95
96
98

99
100
101
104
106

Safety and general instructions

Please observe these instructions in the interest of your own
safety.

1.1

The boiler must only be used for its designated purpose,
observing the Installation Instructions.

–

Only use the boiler in the combinations and with the accessories and spares listed.

–

Other combinations, accessories and consumables must
only be used if they are specifically designed for the intended
application and do not affect the system performance and the
safety requirements.

–

Maintenance and repairs must only be carried out by authorized professionals.

–

You must report the installation of a condensing gas boiler to
the relevant gas utility company and have it approved.

–

You are only allowed to operate the condensing gas boiler
with the combustion air/flue gas system that has been specifically designed and approved for this type of boiler.

–

Please note that local permission for the flue system and the
condensate water connection to the public sewer system
may be required.

–

You must also observe:

–

the local building regulations stipulating the installation rules.

–

the local building regulations concerning the air intake and
outlet systems and the chimney connection.

Indicates the presence of hazards that can
cause severe personal injury, death or substantial property damage.

–

the regulations for the power supply connection.

–

the technical rules laid down by the gas utility company concerning the connection of the gas burner fitting to the local
gas main.

CAUTION:

–

Indicates presence of hazards that can cause
minor personal injury or property damage.

the instructions and standards concerning the safety equipment for the water/space heating system.

–

the Installation Instructions for building heating systems.

–

The boiler must be located in an area where leakage of the
tank or connections will not result in damage to the area adjacent to the boiler or to lower floors of the structure. When
such locations cannot be avoided, it is recommended that a
suitable drain pan, adequately drained, be installed under the
boiler. The pan must not restrict combustion air flow.

–

The boiler must be installed such that the gas ignition system
components are protected from water (dripping, spraying,
rain etc.) during boiler operation and service.

–

The boiler must not be installed on carpeting.

–

Do not restrict or seal any air intake or outlet openings.

–

If you find any defects, you must inform the owner of the system of the defect and the associated hazard in writing.

Hazard definitions

The following defined terms are used throughout the documentation to bring attention to the presence of hazards of various risk
levels. Notices give important information concerning the life of
the product.
DANGER:
Indicates the presence of hazards that can
cause severe personal injury, death or substantial property damage.
WARNING:

CAUTION:
Risk of electric shock.
Indicates presence of hazards due to electric
shock.
NOTICE:
Indicates special instructions on installation,
operation or maintenance that are important but
not related to personal injury or property
damage.

The following instructions must be
observed

–

Designated use

The boiler was designed for heating water for a space heating
system and generating hot water e.g. for domestic purposes.
The boiler is delivered with a BC10 basic controller and the
"Universal Automatic Burner Control Unit 3" (UBA 3) preinstalled.
The boiler can be fitted with a modulating outdoor reset control
AM10 (scope of delivery) and an On/Off thermostat or relay
panel end switch (24 V) (accessories).

1.2

1.3

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Safety and general instructions

DANGER
if flammable gas explodes.
Beware if you smell gas: there may be an
explosion hazard!
Warning: If the information in these instructions is not followed exactly, a fire or explosion may result causing property damage,
personal injury or death.

1.6

Inspection

We advise you to offer your customer an annual inspection and
maintenance contract. If inspection reveals that maintenance
work is necessary you can carry this out as required in the Installation instruction of the boiler.
Installation
CAUTION:

 Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this
or any other boiler.
What to do if you smell gas
 Do not try to light any boiler.

–

Carry out a maintenance overhaul if necessary. Immediately repair defects to avoid
damage to the heating system!

Periodically examine the venting systems and cleaning of the
screens in the vent terminal.

 Immediately call your gas supplier from a
neighbor’s phone. Follow the gas supplier’s
instructions.

–

Also periodically inspect the low water cutoffs, including
flushing of float types.

–

And periodically inspect the burner flames (see page 8, fig. 1,
pos. 10).

–

Check the neutralization unit if present.

–

Check to see if there are no obstructions to the flow combustion and ventilation air.

–

For direct vent boilers, proper reassembly and resealing of
the vent-air intake system is required.

Observe these instructions for heating
system water

–

Thoroughly flush the system prior to filling.
Only use untreated main water to fill and top off the system.

–

Do not use salt bedding exchangers to soften the water.

–

Do not use inhibitors or other additives!

–

No Toxic chemicals such as used for boiler treatment, shall
be introduced into the heating water used for space heating.

–

The maximum permissible flow rate of the GB142-24/30 this
is 11 GPM (gal./min.), for the GB142-45 is 15 GPM and for
the GB142-60 is 20 GPM.
When using oxygen-permeable pipes, e. g. for floor heating
systems, you must separate the system using heat exchangers. Unsuitable heating system water promotes the formation
of sludge and corrosion.
This may damage the heat exchanger or affect its operation.

1.5

Check and clean the heating system at least
once a year.

–

Installation and service must be performed by a
qualified installer, service agency or the gas
supplier.

–

 Do not touch any electrical switch; do not use
any phone in your building.

 If you cannot reach your gas supplier, call the
fire department.

1.4

Maintenance
–

Cleaning the heat exchanger, the burner and the condensate
trap (see installation instructions, Maintenance).

–

Checking the ionization signal (par. 8.1.15, page 95)

–

Checking and adjusting the gas/air ratio (par. 8.1.26,
page 108).

1.7

Disposal

–

Dispose of the boiler packaging in an environmentally sound
manner.

–

Dispose of components of the heating system
(e. g. boiler or control device), that must be replaced, by
handing them in to an authorized recycling facility.

–

Keep boiler area clear and free from combustible materials,
gasoline and other flammable vapors and liquids.

Tools, materials and additional equipment

For the installation and maintenance of the boiler you will need
the standard tools for central heating, gas and water fitting.
In addition, a handtruck with a fastening belt is very useful.

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

1.8

Safety and general instructions

Abbreviations

AM10
AS
AV
BC
BC10
BCT
BDV
BKS
CB
CH
CHF
CHR
CM10
CT
CWDO
CM10
DHW
DV
E
EM10
EMS
FA
HK1 or HK2
KIM
L
LED
LSV
MCW
MM10
N
PE
PL
Prog
RT or RC
SC
T
TRV
ÜC
UBA 3
VKS
WC
WM10
ZV

=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=

Outdoor reset module
System fault code
Air Vent
Operating code
Control panel (on the boiler)
Boulter Buderus cylinder thermostat
Boulter Buderus diverter valve
Blocking boiler fault code
Connection Block
Central Heating
Central Heating Supply
Central Heating Return
Cascade module
Cylinder Thermostat
Condensate water drainage outlet
Cascade module
Domestic Hot Water
Diverter Valve
Earth
External control module
Energy management system
Outdoor sensor
Central Heating line
Boiler identification module
Live Line
Light Emitting Diode
Lock Shield Valve
Mains Cold Water
Controler for HK2, second Central Heating line module.
Neutal
Ground
Permanent hot line
Programmer
Room Thermostat
Service code
Timer
Thermostatic Radiator Valve
Other display codes
Universal automatic burner control unit 3
Locking boiler fault code
Wiring Centre
Controler for HK1, first Central Heating line
Two Port Zone Valve

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Regulations and guidelines

The installation must conform to the requirements of the authority
having jurisdiction or, in the absence of such requirements, to the
latest edition of the National Fuel Gas Code, ANSI Z223.1. In
Canada, installation must be in accordance with the requirements of CAN/CSA B149.1, Natural Gas and Propane Installation Code.
Where required by the authority having jurisdiction, the installation must conform to the Standard for Controls and Safety
Devices for Automatically Fired Boilers, ANSI/ASME CSD-1.
Install CO detectors per local regulations. The boiler requires
yearly maintenance, see maintenance section see chapter
„8.1.27 Measuring the carbon monoxide content (CO)“ on
page 109.

Operating Limits of the boiler:
Max. boiler temperature:
Max. operating pressure:

220 °F (105 °C)
44 psi (3 bar)

The hot water distribution system must comply with all
applicable codes and regulations. When replacing an existing
boiler, it is important to check the condition of the entire hot water
distribution system to ensure safe operation.
Massachusetts Installations Only:

A metal or plastic identification plate shall be mounted at the
exterior of the building, four feet directly above the location
of vent terminal. The plate shall be of sufficient size to be
easily read from a distance of eight feet away, and read "Gas
Vent Directly Below".
b) For direct-vent boilers mechanical-vent heating boilers
or domestic hot water equipment where the bottom of
the vent terminal and the intake is installed four feet or
above grade the following requirements must be
satisfied:
1) If there is not one already present, a carbon monoxide
detector and alarm shall be placed in the living area
outside the bedrooms, The carbon monoxide detector
and alarm shall comply with NFPA 720 (2005 Edition).
2) A carbon monoxide detector shall:
a) Be located inn the area where the boiler or
equipment is located:
b) Have battery back-up power:
c) Be a minimum comply with NFPA 720
(2005 Edition).
3) A product-approved vent terminal must be used, and if
applicable, a product-approved air intake must be used.
Installation shall be in strict compliance with the
manufacturer's instructions. A copy of the installation
instructions shall remain with the boiler or equipment at
the completion of the installation.

For direct- vent boilers, mechanical-vent heating boilers or
domestic hot water equipment, where the bottom of the vent
terminal and the intake is installed below four feet above grade
the following requirements must be satisfied:
1) If there is not one already present, a carbon monoxide
detector and alarm shall be placed in a living area outside
the bedrooms. The carbon monoxide detector and alarm
shall comply with NFPA 720 (2005 Edition).
2) A carbon Monoxide detector and alarm shall be located in
the room that houses the boiler or equipment and shall:
a) Be powered by in series on the same electrical circuit as
the boiler or equipment:
b) Have battery back-up power:
c) Meet ANSI/UL 2034 Standards and comply with
NFPA 720 (2005 Edition):
d) Have been approved and listed by a Nationally
Recognized Testing Lab:
3) A product-approved vent terminal must be used, and if
applicable, a Product approved air intake must be used.
Installation shall be in strict compliance with the
manufacturer's instructions. A copy of the installation.

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Product description

Product description
7

9
10
11
5

9
10
11

12
3

1
fig. 1

pos. 1:
pos. 2:
pos. 3:
pos. 4:
pos. 5:
pos. 6:
pos. 7:
pos. 8:
pos. 9:

5 6
110

120

130

130
150
170

140

190

12 11 10 9

Basic Controller Logamatic BC10

pos. 1:
pos. 2:
pos. 3:
pos. 4:
pos. 5:
pos. 6:

Sighting glass
Heat exchanger
Back cover
Air intake for the fan
Fan
Condensate trap and internal condensate drain flue
gas pipe
pos. 16: External Connection Board (under the cover)
pos. 17: Pressure sensor

110
100

15 13 16

pos. 10:
pos. 11:
pos. 12:
pos. 13:
pos. 14:
pos. 15:

Drawer with control unit
Universal Burner Automat (UBA 3)
Control unit BC10
Gas valve
Cover
Flue measuring points
Parallel flue
Burner
Latches of which two have locks

fig. 2

Logamax plus GB142-24/30 (left) and GB142-45/60 (right)

Main switch
DHW temperature knob 1)
LED "DHW status"
Display
Space heating water temperature knob
LED "Heating system status"

pos. 7:
pos. 8:
pos. 9:
pos. 10:
pos. 11:
pos. 12:

Under the cover a RC system controller can be installed.
LED "Burner Operation"
Service Tool connector
"Service" e button
"Chimney sweep" d button
"Reset" c button

ECO mode means that the temperature inside the hot water tank is 140 °F (60 °C), with a hysteresis (ΔT) of 18 °F instead of 9 °F

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Operation

4.1

Operating the BC10 basic controller

4.1.1

General

The boiler is equipped with an control unit, the basic controller
BC10. The BC10 allows you to operate the boiler.
 Briefly press on the control panel cover to open it
(see fig. 3).
The basic controller BC10 (see fig. 2) is located on the left side in
the drawer.
On the right side of the drawer there’s space for a RC control unit.
4.1.2

fig. 3

Opening the control panel

Switching the heating system on and off

Switching on the heating system
 Set the main switch on the BC10 basic controller to position "1"
(On).
Switching off the heating system
 Set the main switch on the BC10 basic controller to position "0"
(Off).

4.2

Menu structure of the BC10 basic controller

The menu structure of the boiler can be viewed on the BC10 using
, "Chimney sweep
" and "Service
" (see
the "Reset"
fig. 2, pos. 9, 10 and 11) buttons and the display indication (see
fig. 2, pos. 4).

The menu structure consists of 4 menus, schematically
represented on the following pages using structure diagrams:
–

"Flue gas test" menu (page 10)

–

"Service Mode" menu (page 11)

–

"Manual Operation" menu (page 12)

–

"Settings" menu (page 12).

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

4
4.2.1

Operation
"Flue gas test" menu
"FLUE GAS TEST" MENU

Current supply temperature 0 ... 199 °F
(-18 ... 93 °C). See page 20.

Activate
flue gas test?
yes

Activate flue gas test:
Press and hold the chimney sweep button
2 to 5 seconds.

7 2.

The flue gas test is activated as soon as a dot is
visible in the lower right hand corner of the
display. This means that the boiler runs in
heating mode at 100 % for 30 minutes. The
maximum boiler water temperature as set on
the BC10 basic controller applies here.

Press the service button.

P2 9.

psi

Current heating system pressure. See page 20.

Press the service button.

A .

Operating code. See page 21.

Press the service button.

7 2.

Current supply temperature 0 ... 199 °F
(-18 .. 93 °C). See page 20.
Have
30 min. passed or
was the power
interrupted?

yes

no
no

Deactivate
flue gas test?
yes

Deactivate flue gas test:
Press and hold the chimney sweep button for
more than 2 seconds, until the decimal point
has disappeared.

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Operation
4.2.2

"Service Mode" menu
"SERVICE MODE" MENU

Current supply temperature 0 ... 199 °F
(-18 ... 93 °C). See page 20.
Activate
service mode?

yes

Boiler load in line with "Settings" menu.
Activate service mode 1st step:
Press and hold the "Chimney sweep" button
for 2 to 5 seconds.

7 2.

As soon as a non-flashing dot is shown in the
right-hand bottom corner of the display, the
boiler will run in heating mode at 100 % load for
30 minutes. The maximum boiler water
temperature set on the BC10 basic controller
applies.
+
Activate service mode 2nd step:
Simultaneously press and hold the "Chimney
sweep" and "Service" buttons for more than
2 seconds.

L .
Current boiler load. See page 20.

P2 9.

psi

Current heating system pressure. See page 20.

Service mode activated.
You can now temporarily lower the boiler load
to partial load to check, and if relevant set the
gas/air ratio or the ionization current.

Press the "Service" button.

A .

Operating code. See page 46.

Press and hold the "Reset" button until the
display shows "L30."
Press the "Service" button.

L3 0.

7 2.

Current boiler load. See page 20.
The boiler will reduce its load to 30 % within a
couple of seconds. The maximum boiler water
temperature as set on the BC10 basic controller
applies. Check the gas/air ratio (see page 108)
or the ionization current (see page 95) and
adjust the gas/air ratio if necessary.

Current supply temperature 0 ... 199 °F
(-18 ... 93 °C). See page 20.

Have 30 min.
passed or was the
power interrupted?
no

Press the "Service" button.
no

7 2.

Current supply temperature 0 ... 199 °F
(-18 ... 93 °C). See page 20.

Press the "Service" button.

yes

Deactivate
service mode?
yes

Deactivate service mode:
Press and hold the "Chimney sweep" button for
more than 2 seconds until the decimal point
has disappeared.

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

4
4.2.3

Operation
"Manual Operation" menu
"MANUAL OPERATION" MENU

Current supply temperature 0 ... 199 °F
(-18 ... 93 °C). See page 20.

Activate manual
operation?

yes

To activate manual operation:
Press and hold the "Chimney sweep" button for
more than 5 seconds.

7 2.
As soon as a flashing dot is shown in the righthand bottom corner of the display, manual
operation is active. The means that the boiler is
permanently in heating mode. The maximum
boiler water temperature as set on the BC10
basic controller now applies. The "Heat
request" LED is lit.

Press the "Service" button.

P2 9.

psi

Current heating system pressure. See page 20.

Press the "Service" button.

H .
Operating code. See page 20.
During manual operation the "Adjustments"
menu on page 12 can be used to temporarily
change the required boiler load in case of an
emergency.

Power
interrupted?

Press the "Service" button.

yes

7 2.
Current supply temperature 0 ... 199 °F
(-18 ... 93 °C). See page 20.

Deactivate manual
operation?
yes

Deactivate manual operation:
Press and hold the "Chimney sweep" button for
more than 2 seconds until the flashing decimal
point has disappeared.

4.2.4

"Adjustments" menu

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Operation

"ADJUSTMENTS" MENU

Current supply temperature 0 ... 199 °F
(-18 ... 93 °C). See page 20.
Open the
“Adjustments” menu?

yes

Boiler load and pump post purge
time settings confirmed.

Open programming mode: Simultaneously
press and hold the "Chimney sweep" and
"Service" buttons for more than 2 seconds.

As soon as the display shows "L--", the
programming mode is open. The first
parameter shown on the display is used to set
the boiler load for heating operation.
yes, lower

yes, higher

Adjust boiler load?
no

Adjust the boiler load with
the "Reset" button.

Adjust the boiler load with
the "Chimney sweep" button.

L3 0

„L__“ is the maximum
heating load setting of 100 %.
Factory default setting: "L " = 100 %.

The setting "L30" means that the
heating load is lowered to 30 %.

Press the "Service" button.

F 5

As soon as the display shows "F ", the second
parameter can be set. This parameter
indicates the pump post purge time.
yes, lower

Adjust pump post
purge time?

yes, higher

Adjust the pump post purge time with
the "Reset" button.

Adjust the pump post purge time with the
"Chimney sweep" button.

F 00

F 1d

"F00" is the minimum pump post purge time
setting in minutes. "F60" is the maximum
pump post purge time setting in minutes.

"F1d" is the maximum
pump post purge time setting for one day.
Factory default setting "F 5" = 5 minutes.

Have at least
5 min. passed without a button being
pressed or was the power supply
interrupted ?

yes

Press the "Service" button.

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Function

5.1

General

To clarify the operation of the Logamax plus GB142-24/30/45/60
thermal power gas boilers under normal operating conditions, the
work steps are schematically represented in the structure diagrams
on the following pages of this chapter.

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Function

5.2

Structure diagram "Function"
1
Start up

Connect the heating system to the power grid
by turning the circuit breaker ON.
Turn the main switch on the BC10 to
position “1” (ON), see page 8, fig. 2.
The LED of the UBA 3 lights for 1 second.
This means that the UBA 3 is reading the
KIM. If a new KIM or UBA 3 has been
installed, the LED will flash at a high
frequency for max. 10 sec. while data is being
exchanged.

8.8.8.
A display check is carried out
(for max. 1 second).

Flashes twice for 2 seconds until
communication between the UBA 3 and the
BC10 has been established.

72
Current supply temperature 0 ... 199 °F
(-18 ... 93 °C). See page 20.

Press the "Service" button.

P29

0U
Operating code.
The heating boiler is started.
Start of air-side pre-flushing phase.
The blower runs for < 20 seconds at
approx. 60 % of the maximum speed.

psi

Current heating system pressure.
See page 20.

Is the
air purging phase
okay?

Unit will show an error code.
Fault must be fixed before
proceeding.
See chapter 6, 7 and 7.2.

yes
Press the "Service" button.

page 16

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Function

page 15

0H
Operating code.
The boiler is in ready mode,
there is no heat request.

Start of pump post purge time via the heating
system. Pump post purge time in line with
"Settings" menu.
See page 12 and page 20.
Factory default setting: 5 minutes.

Has the pump post
purge time expired?

yes

Is
the
temperature
in the hot water
no
tank at least
9 °F (5 K)lower than the
temperature set
on the BC10
or RC?

page 18

Has the primary
circulation pump been off for
more than 24 hours?

page 17

page 19

Is
the
temperature
in the hot water
no
tank at least
9 °F (5 K) lower than
the temperature set
on the BC10
or RC?

yes

The primary circulation pump stops.

Is
there a heat
request from the
room or outdoor
temperaturedependent
regulator?

yes
yes

yes
The primary circulation pump is run for
10 seconds to prevent it from seizing up.

Have ten seconds
passed or was the power supply
interrupted?
yes

page 17

page 19

Is
the
temperature
in the hot water
no
tank at least
9 °F (5 K) lower than
the temperature set
on the BC10
or RC?

Is
there a heat
request from the
room or outdoor
temperaturedependent
regulator?

yes

page 17

page 19

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Function

page 16

The "Hot water mode" LED on the
BC10 is lit.

0C
The blower is started up.
The tank filling pump
is activated.
The hot surface ignitor is activated
for seven seconds.
The primary circulation pump
is started.

0L
Ignition phase:
The gas valve is opened.

page 19

Is
the supply
temperature 82.8 K
higher than the hot water
temperature setting
or higher than
200 °F (93 °C)?

GB142 is in the hot water mode.
The "Burner" LED is lit.

Is the temperature
in the hot water tank higher
than the hot water temperature setting
in the BC10 or RC control
device?

yes

0Y
The gas valve is closed,
the burner is shut down.

yes
The "Hot water mode" LED
goes off.

The "Burner" LED goes off.

The blower stops.

4
page 18
no

Is
the supply
temperature lower
than the preset
hot water temperature
plus 63 °F (35 K)?

yes

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Function

page 18

0A
The gas valve is closed,
the burner is shut down.
The "Burner" LED goes off.
Start the pump over-run time through the hot
water tank at least 30 seconds,
max. 1 minute, if there is a heat request.
Air-side after-purging by blower
for 30 seconds.

The blower stops.

0H
The primary circulation pump stops.
The tank filling pump
is stopped.

Is there a
heat request from the room or
outdoor temperature-dependent
regulator?

5
page 16

yes

6
page 19

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Function

page 16, page 18

6
The "Heat request" LED is lit.

0C
The blower is started up.
The hot surface ignitor is activated for
seven seconds.
The circulation pump is started up.

0L
Ignition phase:
The gas valve is opened.

H
The GB142 enters heating mode.
The "Burner" LED is lit.
Is the
temperature in the hot water
at least 9 °F (5 K) lower than the temperature
set on the BC10 or RC?

no
Is the
room or outdoor temperaturedependent regulator in the request
position?

yes

page 17
Is
the supply
temperature
11 °F (6 K) higher than
the target value? (The target value
is calculated by the outdoor
temperature-dependent regulator
or is set - in the event of room
temperature-dependent
regulation- on the
BC10)

yes

no
The "Heat request" LED goes off.

Yes

0H
The gas valve is closed,
the burner is shut down.

The gas valve is closed,
the burner is shut down.

The "Burner" LED goes off.

Start of pump post purge time via the heating
system. Pump post purge time in line with
"Settings" menu. See page 12 and page 20.
Factory default setting: 5 minutes.
Air-side after-purging by blower for
30 seconds.
The primary circulation pump stops.

The blower stops.

Is
the supply
temperature 11 °F (6 K)
lower than the
target value?

yes

The blower stops.

5
page 16

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Symptoms

6.1

Display indication on the BC10 basic controller

6.1.1

General

A display value or code is shown on the display of the BC 10 basic controller (see page 8, fig. 2).
6.1.2

Display values on the display of the BC10 basic controller

The display value is shown automatically or can be called up by pressing the "Chimney sweep
page 10 and 12.

d" or "Service e" button (see

The following display values can be shown on the display of the BC10 basic controller:
Display
value
[\/7/2|

Type of display value

Unit

Current supply temperature

°F

[\/\/0|

–

[l/9/9| 1)

°C

[-/1/8|

–

[\/9/3|

[p/2/9|

Current heating system pressure

psi

[p/0/0|

–

[p/2/9|

[l/9/9|

Configured target load

[l/3/0|

–

[l/9/9|

[l/?/?|

[f/\/5|

Configured target pump post purge time

min

[f/0/0|

–

[f/6/0|

[f/1/d|

[f/\/5|

table 1
6.1.3

Display values on the BC10 basic controller
Display codes on the display of the BC10 basic
controller

A display code shows the current status of the Logamax plus
GB142.
The display value is shown automatically or can be called up by
" button.
pressing the "Service

Two display codes (see table 2 level 3 and level 4) are shown.
After the first display code (level 3) is displayed, the second one
“ button. On
(level 4) can be called up by pushing the “Service
the BC10 basic controller level 4 can only be called up in the event
of a fault code.

Under normal operating conditions it is only possible to call up level
4 using the RC control device or a service tool.

Factory
default
setting

Range

If the display code is a fault code, this fault code either flashes
(locked fault code) in the display or it is shown permanently
(blocking fault code). A boiler reset is only necessary with a
locking fault code (flashing) (see 8, fig. 2). The cause of the
fault must be remedied first. The cause has to be remedied
and the boiler resumes regular operation.
In the event of a locking boiler fault code both the display
value and the display code flash.
If there are more than once display codes at the same time,
the display codes will be shown in turn. And if one of these
display codes is a locking display code, the blocking display
codes shown will also flash.

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Symptoms

The following display values can be shown on the display of
the BC10 basic controller:
Abbreviations used in table 2:
Type of display code:
BC - Operating code
SC – Service code
BKS – Blocking boiler fault code
VKS – Locking boiler fault code (flashing)
AS – System fault code
ÜC – Other display codes
Symptoms
Display code

Main
display
code

[\/\/\|

Subdisplay
code

[-/a/\]

[2/0/8|

or any other
indication
with a
permanent
dot in the
bottom
right-hand
corner.

[-/h/\|

Type of
display
code

[\/\/\|

[\/-/\|

Key to display code

[2/0/0|

Reset
required
?

Other
symptoms

No indication in
display.
Communication test while starting up.
This code flashes 2 x 2 seconds while
starting up to indicate that the
communication between the UBA 3 and
the BC10 basic controller is being tested.
If a new UBA 3 or a new KIM was fitted,
this code will flash for
max. 10 seconds. If this code continues
to flash on the display, there is a fault in
the communication between the UBA 3
and the BC10 basic controller.
See page 46.
This fault code will also appear when
connecting a thermostat to the RC
terminals.

ÜC

The boiler is in the flue gas test mode or
in service mode.

The boiler is in heating mode.

The boiler is in manual operation mode.

The boiler is in hot water mode.

The boiler has switched off. Start the
pump over-run time via the tank for at
least 30 seconds and maximum
1 minute.

Diagnosis

Remedy

page 28

page 10 or
page 11

page 10 or page 11

page 12

No heating
operation and no
hot water.

[-/h/}

any other
indication
with a
flashing dot
in the
bottom
right-hand
corner.

[=/h/\|

[2/0/0|

[2/0/1|

The room
temperature is too
high.

[0/a/\|

[3/0/5|
1)

table 2
1)
2)

Display indications on the BC10 basic controller

only visible using the service tool
is being carried out

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Symptoms

Symptoms
Display code

Main
display
code

Subdisplay
code

[0/a/\|

[2/0/2|

Key to display code

Operating phase:
The switch optimization program is
activated.

Type of
display
code

Reset
required
?

Other
symptoms

Diagnosis

Remedy

Possibly no
heating operation.

This program is activated if there is more
than one burner firing requests from an
RC or ON/OFF regulator within 10
minutes.
This means that the boiler cannot be
restarted until at least ten minutes have
elapsed since initial startup of the burner.

[0/c/\|

[2/8/3|

The burner is started.

Readiness for operation:
The boiler is in ready mode.
The time-proportional program is
activated.

[0/e/\|

[2/6/5|
1)

The time-proportional program is
activated as soon the load requested by
the modulating room controller is lower
than the lower limit of the boiler load.
During the time-proportional program the
burner is switched on and off repeatedly.
The period in which the burner is
switched on depends on the difference
between the load required by the
modulating room controller and the lower
limit of the boiler load. As soon as the
burner is switched on, the device is
operating at minimum load. As soon as
the burner is switched off, the display
[2/6/5| is indicated in the
code [0/e/\|
display of the BC10.

The time-proportional program is
deactivated automatically as soon as the
load required by the modulating room
controller is higher than the lower limit of
the boiler load.

[0/h/\|

The boiler is in ready mode, there is no
heat request.

The gas valve is opened.

Power Up.
Boiler is starting up after a reset or after
the main power is switched on.
This display code will be displayed for 4
minutes maximum.

[2/0/4|

The boiler switches off, the temperature
is higher than the target temperature.

[2/0/3|
1)

[0/l/\|

[2/8/4|
1)

e
e

[0/u/\|

[0/y/\|

e
e

[2/7/0|

[0/y/\|

[2/7/6|

The supply sensor has measured
a temperature higher than 203 °F
(95 °C).

BKS

[0/y/\|

[2/7/7|

The safety sensor has measured
a temperature higher than
203 °F (95 °C).

BKS

[0/y/\|

[2/8/5|

The return sensor has measured
a temperature higher than
203 °F (95 °C).

BKS

table 2
1)
2)

Display indications on the BC10 basic controller

only visible using the service tool
is being carried out

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Symptoms

Symptoms
Display code

Main
display
code

Type of
display
code

Reset
required
?

Flue gas sensor is activated
(not available).

BKS

Flue gas sensor
has measured a
flue gas temperature higher than
221 °F (105 °C)

The UBA 3 does not register any
connections to the unused contacts 78
and 50.

BKS

The system pressure is too low.

BKS

Subdisplay
code

[1/c/\|

[2/1/0|

[1/l/\|

[2/1/1|

[2/e/\|

[2/0/7|

[2/f/\|

[2/6/0|
1)

Key to display code

No temperature increase after burner
start or the temperature difference
between the supply and safety sensors is
more than 27 °F (15 K).

Diagnosis

Remedy

No heating
operation and no
hot water.

page 48

No heating
operation and no
hot water.

page 48

page 49

page 50

Other
symptoms

[2/f/\|

[2/7/1|

The temperature difference between the
supply and safety sensors is more than
27 °F (15 K).

BKS

[2/l/\|

[2/6/6|

The primary circulation pump does not
generate a pressure difference.

VKS

yes

[2/p/\|

[2/1/2|

Temperature increase of supply sensor
or safety sensor is more than 9 °F/sec
(5 K/sec).

page 52

The temperature difference between the
supply and return sensors is more than
90 °F (50 K).

page 53

[2/u/\|

[2/1/3|
1)

e
e
e

[3/l/\|

e
e
e

[3/p/\|

No heating
operation and
no hot water.

The air flow by the blower has failed
during the operating phase.

BKS

page 54

The blower is switched off during the
safety test.

BKS

page 55

[2/1/4|

e
e
e

The blower is switched off during the
safety test.

VKS

yes

No heating
operation and
no hot water.

page 56

[2/1/6|

The blower is running too slowly.

VKS

yes

No heating
operation and
no hot water.

page 57

[3/y/\|

[2/1/5|

The blower is running too fast.

VKS

yes

No heating
operation and
no hot water.

page 58

[4/a/\|

[2/1/8|

The supply sensor has measured a
temperature higher than 221 °F (105 °C).

VKS

yes

No heating
operation and
no hot water.

page 59

[4/c/\|

[2/2/4|

The UBA 3 does not register the short cut
bestween the unused contacts 22 and
24.

VKS

yes

No heating
operation and
no hot water.

page 60

[4/e/\|

[2/7/8|

The sensor test has failed.

VKS

yes

No heating
operation and
no hot water.

page 60

[4/l/\|

[2/2/0|

The safety sensor is shorted or
measures temperatures higher than 266
°F (130 °C).

VKS

yes

No heating
operation and
no hot water.

page 61

[4/p/\|

[2/2/1|

The safety sensor contact
is interrupted.

VKS

yes

No heating
operation and
no hot water.

page 62

[4/u/\|

[2/2/2|

The supply sensor is shorted.

VKS

yes

No heating
operation and no
hot water.

page 63

[3/a/\|
[3/f/\|

table 2
1)
2)

[2/6/4|
[2/7/3|

Display indications on the BC10 basic controller

only visible using the service tool
is being carried out

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Symptoms

Symptoms
Display code

Type of
display
code

Reset
required
?

The supply sensor contact is interrupted.

VKS

yes

No ionization after ignition.
After four startup attempts, a locking
boiler fault follows [6/a/\|.

BKS

[2/2/7|

No ionization after four startup attempts.

VKS

yes

[2/2/8|

An ionization current was measured
before the burner start.

VKS

[6/c/\|

[3/0/6|

An ionization current was measured after
the burner switch-off.

[6/l/\|

[2/2/9|

[6/p/\|

e
e

[2/6/9|

e
e

[7/c/\|

[2/3/1|

[7/l/\|

e
e

[7/l/\|

e
e

Main
display
code

Diagnosis

Remedy

page 64

page 65

No heating
operation and
no hot water.

page 65

yes

No heating
operation and
no hot water.

page 72

VKS

yes

No heating
operation and
no hot water.

page 72

Ionization fails during the operating
phase.

BKS

page 73

The hot surface ignitor activates too long.

VKS

yes

No heating
operation and
no hot water.

page 78

The power supply was interrupted and
switched on again after a fault message.

VKS

yes

No heating
operation and
no hot water.

page 78

[2/6/1|

The UBA 3 is defective.

VKS

yes

No heating
operation and
no hot water.

page 78

[2/8/0|

The UBA 3 is defective.

VKS

yes
page 79

page 79

Subdisplay
code

[4/y/\|

[2/2/3|

[6/a/\|

[2/2/7|

[6/a/\|

[6/c/\|

e
e
e

[8/y/\|

[2/3/2|

Key to display code

The external switch contact is activated.

Display test while starting up. This code
is displayed for a maximum of 1 second.

ÜC

Other
symptoms

No heating
operation and
no hot water.

[8.8.8]

[9/a/\|

[2/3/5|

KIM or UBA 3 is defective.

VKS

yes

No heating
operation and
no hot water.

page 80

[9/h/\|

[2/3/7|

KIM or UBA 3 is defective.

VKS

yes

No heating
operation and
no hot water.

page 80

[9/h/\|

[2/6/7|

The UBA 3 is defective.

VKS

yes

No heating
operation and
no hot water.

[9/h/\|

[2/7/2|

The UBA 3 is defective.

VKS

yes

No heating
operation and
no hot water.

[9/l/\|

[2/3/4|

The gas valve coil or the wiring to the gas
valve is defective.

VKS

yes

No heating
operation and
no hot water.

page 81

e
e

[9/l/\|

[2/3/8|

VKS

yes

[2/3/9|

e
e

The UBA 3 is defective.

[9/p/\|

e
e

KIM or UBA 3 is defective.

VKS

yes

No heating
operation and
no hot water.

page 80

[9/u/\|

[2/3/3|

KIM or UBA 3 is defective.

VKS

yes

No heating
operation and
no hot water.

page 80

table 2
1)
2)

Display indications on the BC10 basic controller

only visible using the service tool
is being carried out

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Symptoms

Symptoms
Display code

Main
display
code

[a/0/1|

e
e

[a/0/1|
[a/0/1|

[a/0/1|

Subdisplay
code

[8/0/0|

e
e

[8/0/8|
[8/0/9|

[8/1/0|

[8/1/1|

e
e

Key to display code

Outdoor sensor

Hot water temperature sensor

Type of
display
code
AS

Reset
required
?

Diagnosis

Remedy

Sensor
connected or
fitted incorrectly.

Check the sensor
connection and the
sensor wire.

Sensor wire
broken or
shorted.

Check the sensor
installation.

The sensor is
defective.

Compare the
resistance value to
the sensor graph.

Sensor
connected or
fitted incorrectly.

Check the sensor
connection and the
sensor wire.

Sensor wire
broken or
shorted.

Check the sensor
installation on the
hot water tank.

The sensor is
defective.

Compare the
resistance value to
the sensor graph.

The system
constantly tries to
heat the hot water
tank to the hot
water target value
setting.

Permanent
tapping or leak.

Remedy the leak if
relevant.

Sensor
connected or
fitted incorrectly.

Check the sensor
connection and the
sensor wire.

The hot water
priority is
cancelled when
the fault message
appears.

Sensor wire
broken or
shorted.

Check the sensor
installation on the
hot water tank.

The sensor is
defective.

Compare the
resistance value to
the sensor graph.

Fill pump
connected
incorrectly or
defective.

Test the fill pump
operation e. g.
using a relay test.

Tap flow rate too
great during
disinfection
period.

Choose the time for
thermal disinfection
so that no
additional heat
request occurs at
this time.

Other
symptoms

The minimum
outdoor
temperature is
assumed.

No water is
heated any more.

Hot water temperature sensor 2

Hot water remains cold.

Thermal disinfection.

Thermal
disinfection was
interrupted.

Boiler load too
low for
simultaneous
heat use by
other connected
loads (e. g. 2nd
heating circuit).

table 2
1)
2)

Sensor
connected or
fitted incorrectly.

Check the sensor
connection and the
sensor wire.

Sensor wire
broken or
shorted.

Check the sensor
installation on the
hot water tank.

The sensor is
defective.

Compare the
resistance value to
the sensor graph.

Fill pump
defective

Test the fill pump
operation e. g.
using a relay test.

Display indications on the BC10 basic controller

only visible using the service tool
is being carried out

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Symptoms

Symptoms
Display code

Main
display
code

[a/0/1|

Subdisplay
code

[8/1/6|

Key to display code

No communication with EMS.

Type of
display
code
AS

[a/0/1|

[8/2/8|

Water pressure sensor.

[a/0/2|

[8/1/6|

No communication with BC10.

e
e
e
e
e
e

[c/0/\|
[c/0/\|
[c/a/\|
[c/u/\|
[c/y/\|
[e/\/\|

e
e
e
e
e
e

[2/8/8|

The UBA 3 has no connection to the
pressure sensor or there is a short circuit.

[2/9/0|

e
e
e
e
e
e

[2/4/2|

[2/8/9|
[2/8/6|
[2/4/0|
[2/4/1|

Reset
required
?

The boiler no
longer gets heat
requests; the
heating system no
longer heats.

[e/\/\|

[h/\/7|

[r/e/\|
table 2
1)
2)

EMS bus system
is overloaded.

Reset by switching
the heating system
on and off.

UBA 3/MC10 is
defective.

Inform the
BUDERUS
customer service
department if
necessary.

The digital water
pressure sensor
is defective.

Replace the digital
water pressure
sensor.

BC10 settings are
no longer taken
over by RCxx
devices.

Contact problem
at BC10 or BC10
is defective.

Check the BC10
connection.

No heating
operation and no
hot water.

page 82

Replace the BC10
if necessary.

The return sensor has measured a
temperature higher than 221 °F (105 °C).

VKS

yes

The return sensor is shorted.

VKS

yes

The return sensor contact is interrupted.

VKS

yes

The UBA 3 is defective.

BKS

No heating
operation and
no hot water.

page 80

KIM or UBA 3 is defective.

VKS

yes

No heating
operation and
no hot water.

page 80

page 78

page 80

page 78

page 80

Short circuit in connection to pressure
sensor.

[2/8/7|

[h/\/7|

Remedy

yes

+ any digit
or letter

Diagnosis

VKS

+ any digit
or letter

Other
symptoms

The heating system pressure is too low.

Reset is carried out. After pressing the
"Reset" button this code is displayed for
5 seconds.

ÜC

Display indications on the BC10 basic controller

only visible using the service tool
is being carried out

6.2

LED on the UBA 3

In addition to the display indication on the BC10 basic controller, there is a red LED on the UBA 3.
The meaning of this LED is explained in see table 3.
LED

Meaning

Off

Normal operation

Flashing slowly (1 Hz)

There is a boiler fault (locking fault).

Flashing fast (10 seconds)

During startup after replacing the KIM or the UBA 3.

During a fault in the UBA 3 or if the KIM is not recognized.

table 3

LED on the UBA 3

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

7.1

Faults without a fault code

Hot water request
Although the UBA 3 indicates that the system is ready for
operation, it is possible that in the event of a hot water request no
hot water is made available, or it is only made available for a short
time.
Structure diagram for troubleshooting, see page 33.
Heating mode
Although the UBA 3 shows that the system is ready for operation
and the room temperature has not reached the preset value, the
Logamax plus GB142 does not enter the heating mode.
Structure diagram for troubleshooting: page 44.

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

No display

No indication in display.
Do the other
functions of the device work
normally?

yes

19
page 29

Check that the mains power switch
is ON.
Is the mains power
switch ON?

Switch on the mains power switch.

Turn the operating switch on the BC 10 to
position “1” (ON). See page 9 (fig. 2).

Deal with any problem in the electrical
system.

Replace the cable loom (or the affected
part thereof.

yes

Check that the operating switch is in
position “1” (ON). See page 9.
Is the
operating switch on the BC 10 in
position “1” (ON)?
yes

Check that there is a 120V AC power
supply at the mains power switch.

Is there a voltage at the
mains power switch?
yes

Measure the resistance of the 120V AC
supply cord.
Is the 120V AC cord okay?
yes

Check the fuse on the rear of the UBA 3
using a volt-ohm-multimeter.
See page 84.

Is the fuse okay?

yes

44
page 83

Replace the fuse.
See page 84.

Is there any indication on the
BC10 display?

yes

Turn the operating switch on the BC10 to
position “0” (OFF). See page 9, par. 4.2.

page 30

page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

page 28

19
Check that there is between 7.8 and 15.2
VDC on both contacts 1 and 2 of the BC10.
See page 126.

Is there a voltage?

Yes

Replace the BC10.
See the fitting instructions of
the BC10.

No
Measure the relevant part of the cable loom.
See page 126.

Is the cable loom okay?

Replace the cable loom or the
affected part thereof.

Yes

44
page 83

8
page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

No display, part 2

page 28

7
Disconnect the following boiler components
from the electrical power supply:
- the blower, see page 86,
- the primary circulation pump,
see page 126.
Check the fuse on the rear of the UBA 3
again using a volt-ohm-multimeter.
See page 84.

Is the fuse okay?

Replace the fuse again.
See page 84.

Yes

Turn the operating switch on the BC10 to
position “1” (ON). See page 9, par. 4.2.

Is there any indication on the
BC10 display?

9
page 32

Yes
Turn the operating switch
to “0” (OFF).

Connect the external primary
circulation pump.

Turn the operating switch on the BC 10 to
position “1” (ON). See page 9, par. 4.2.

Is there any indication on the
BC10 display?
Yes

Replace the external primary
circulation pump.

Replace the fuse again.
See page 84.

10
page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

No display, part 3

page 30

10
Turn the operating switch on the BC10 to
position “0” (OFF). See page 9, par. 4.2.

Connect the blower. See page 86.

Turn the operating switch on the BC10 to
position “1” (ON). See page 9, par. 4.2.

Is there any indication on the
BC10 display?

Replace the blower.
See page 88.

Yes
Replace the fuse again.
See page 84.

8
page 31

8
Fit the casing.

Turn the operating switch on the BC10 to
position “0” (OFF). See page 9, par. 4.2.
Make the heating system ready
for operation.
Turn the operating switch on the BC10 to
position “1” (ON). See page 9, par. 4.2.
Logamax plus
GB142-15/24/30/45/60 okay.

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

No display, part 4No display, part 5

page 30

Use a volt-ohm-multimeter to check the
supply wires of the primary circulation pump,
the blower and the hot surface ignitor for signs
of short circuiting.
See page 87 and page 93.

Are the wires okay?

Replace the cable loom or the affected part
thereof and the fuse again.
See page 84.

Yes
Use a volt-ohm-multimeter to measure
contacts L and N of the transformer for
resistance.

Is the resistance approx. 50 Ohms?

Replace the transformer,
see page 109.
And replace the fuse again.
See page 84.

Yes

Measure the supply cord of the transformer to
make sure it is not broken or shorted.

Is the supply cord okay?
No

Yes

44
page 83

Replace the supply cord of the transformer
and replace the fuse again.
See page 84.

8
page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Hot water mode not operational; heating mode is operational

No hot water but heating is operational,
possibly radiators become hot without
there being a heat request.
On devices with
external hot water tanks.

Turn the operating switch on the BC10 to
position “0” (OFF) and turn the operating
switch to "1" (ON).
Open hot water tap.
Check that the hot water outlet conduit
immediately under the hot water tank
becomes hot and that the settings on the
RC device are correct.

Does this conduit warm up
to approx. 140 °F (60 °C)?

Yes

11
page 34

No
Check:
- that the hot water supply has been registered with
the control device. See the Operating instructions
of the BC10 and the RC control device.
- that the hot water target value setting is high
enough (140 °F = 60 °C). See page 8, fig 2.
- that the hot water supply is not switched off by the
timer program of the RC control device. See the
Operating Instructions of the RC control device.

Are the settings okay?

Adjust the settings.

Yes
Check that the "Hot water mode" LED
on the BC10 is lit.
See page 8, fig 2.

Is the LED lit?
Yes

12
page 35

page 34

page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Not hot water, branch 001

page 33

11
The cause of the fault is to be found outside
the device and the hot water tank.

Check that the cold water inlet and hot water
outlet conduit connections on the hot water
tank are not reversed.

Are the water-side
conduits connected properly?

Connect the conduits correctly.

Yes
Close the shut-off valve in the cold-water inlet
and open a hot water tap at random to see if
water comes out of it.

Is this the case?

Yes

The cause is then a defective mixer tap, a
thermostat-controlled mixer valve or a short
circuit between the hot- and cold-water
conduit circuits.

Check to see if any other external part of the
heating circuit is a possible cause.

Are such items detected?

Yes

Place the affected components out of service.

page 83

page 31

Not hot water, branch 002
Not hot water, branch 003

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Repl. AA

page 33

12
Check the hot water temperature sensor.
See page 89.

Is the hot water
temperature sensor okay?

Replace the hot water temperature sensor.
See page 91.

Replace the cable loom or the affected part
thereof.

Yes
Check the wire of the hot water temperature
sensor between the terminal strip and the
UBA 3 mounting base using a continuity
checking device. See page 92.

Is the wire okay?
Yes

page 31

page 83

page 33

Check that the burner in the boiler activates
as specified in the structural diagram,
page 17.

Does the burner in the
boiler activate?

Remedy the fault using the structure diagram
that corresponds with the fault code.

Yes
Is a tank filling pump fitted?
Yes

21
page 36

page 39

page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Repl. BB

page 34

21
Check that the tank filling pump
is running.

Is the tank filling
pump running?

Yes

45
page 37

Check that during hot water mode there is a
120V AC voltage on the tank filling pump.

Is the tank filling pump
being activated?

Yes

46
page 37

No
Check the connection board to make sure that
there is 120V AC on both contacts L and N of
connection PS (gray) during hot water mode.
Does
the connection board
have on both contacts L and N of
connection PS 120V AC during hot
water operation?

Yes

Replace the supply
cord of the tank-filling
pump.

No
Check the fuse on the connection board.
Value: 5A. See page 84.
Is the fuse
on the connection board
okay?

Replace the fuse on
the connection board.
See page 84.

Yes
Check the cable loom of the device.

Is the cable loom okay?

Replace the cable
loom.

Yes
Replace the circuit board.

Is the tank filling pump
running?

Yes

page 83

page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

page 36

Check the tank-filling pump for soiling or for
a defective pump impeller wheel.

Is the
tank-filling pump soiled or is the pump
impeller wheel defective?

Yes
Replace or clean the tank filling
pump.

The external hot water tank is furred up.
Decalcify the tank.

8
page 31

page 36

Check that the pump impeller wheel of the
tank filling pump is not blocked.

Is the
pump impeller wheel of the tank filling
pump blocked?

Yes
As described for the primary circulation
pump, the tank filling pump must be turned in
the direction of rotation of the pump using a
screwdriver.

page 31

page 37

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

page 36

47
Check that the capacitor of the
tank filling pump is okay.

Is the
capacitor of the tank filling pump
okay?

Yes
Replace the tank filling
pump.
Replace the
capacitor.

8
page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

page 34

Check the primary circulation pump for
corrosion or scale.
Is there
corrosion or scale inside the primary
circulation pump?

Yes

Clean the primary
circulation pump (inside).

Clean and/or replace the corresponding
components.

No
Check the following elements for soiling and/
or damage:
- the combustion-air inlet conduit
- the air suction tube,
- the gas orifice, see page 101
- the blower, see page 86
- the connection between the blower and the
burner
- the burner
- the heat exchanger, see page 117
- the flue gas conduit.

Are the abovementioned components clean and
free from damage?
Yes
Measure the inlet gas pressure (flow
pressure). See page 107.

Is the inlet gas pressure
okay?

If the required inlet gas pressure is not
available, you should consult the relevant
gas utility company.

Yes

page 40

page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Repl. CC

page 39

Check the gas/air ratio.
See page 108.

Is the gas/air ratio
okay?

Adjust the gas/air ratio.
See page 108.

Yes
Check the hot water tank
for scale build-up.

Is the hot water tank
scaled up?

Yes

Decalcify the tank.

No
Check to see if any other external part
of the heating circuit is a possible cause of
the fault.

Are such items detected?

Yes

Place the affected components out of service.

page 83

page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

hot water but no central heating

hot water available,
no heating operation.
On devices with
external hot water tanks.

Check that the RC control device settings are
correct. See the Operating Instructions of the
RC control device.

Are the RC control
device settings correct?

Increase the temperature setting on the RC
control device. See the Operating Instructions
of the RC control device.

Yes
Check that the "Heating request" LED on the
BC10 is lit. See fig. 2, page 8.

Is the "Heating request"
LED lit?

Check the control device. See page 104.

Yes
Check that the boiler water temperature
setting on the BC10 (see page 9) or the
RC control device is high enough.

Is the boiler water temperature setting high enough?

Increase the boiler water temperature setting
on the BC10 (see page 9) or on the
RC control device.

Increase the boiler load setting.
See "Adjustments" menu on page 12.

Yes
Check that the boiler load setting is correct.
See "Adjustments" menu on page 12.

Is the boiler load setting high
enough?
Yes
Is a
hot water tank connected?

page 83

Yes
Is a
tank pump fitted?
Yes

8
page 31

20
page 42

44
page 83

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Hot water but no central heating continued -2

page 41

Check that the DHW circulation pump is
running, as described for the primary
circulation pump.

Is the
DHW circulation pump running?

Yes

48
page 43

No
Check that during heating mode there is a
120V AC voltage on the DHW circulation
pump.

Is there a
voltage?

Yes

49
page 43

Check the connection board to make sure that
there is 120V AC on both contacts L and N
of connection PS (green) during heating
mode.

Is
there a voltage?

Yes

Replace the supply cord of
the tank-filling pump.

No
Check the cable loom of
the device.

Is the cable loom
okay?

Replace the
cable loom.

Yes
Replace the connection board.

Is the DHW circulation
pump running?

Yes

page 83

page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

page 36

Check the DHW circulation pump for soiling or
for a defective pump impeller wheel.

Is the
DHW circulation pump soiled or is
the pump impeller wheel
defective?

The fault is caused by the
system and not by the
boiler.

Yes
Clean or replace or the DHW circulation
pump.

8
page 31
page 36

Check that the pump impeller wheel is
not blocked.

Is the
pump impeller wheel
blocked?

Yes
As described for the primary circulation
pump, the DHW circulation pump must be
turned in the direction of rotation of the
pump using a screwdriver.

page 31

page 43

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

page 36

50
Check that the capacitor of the DHW
circulation pump is okay.

Is the
capacitor of the DHW circulation
pump okay?

Replace the capacitor.

Yes
Replace the DHW circulation pump.

8
page 31

Hot water but no central heating continued -3
no central heating

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

No digital pressure display

No digital system water pressure indication on
the display of the BC10 basic controller.

Check that the cable plug from the pressure
sensor is connected.
See page 8, fig. 1, pos. 17.

Is the plug-and-socket
connection okay?

Reconnect the plug-and-socket connection of
the pressure sensor.
See page 8, fig. 1, pos. 17.

Yes
Check the wires between the pressure sensor
plug and the UBA 3 mounting base, by using
a proper measuring device.
See page 126, fig 110.

Is the wiring
okay?

Replace the cable loom or the affected
part thereof.

Yes
Replace the pressure sensor to test whether
the fault can be traced back to the sensor.
See page 116, paragraph 8.1.33.

Can a pressure
indication be read out on the
display?

Yes

44
page 83

8
page 29

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

7.2

Diagnosis

Faults with a fault code

The following structural diagrams can be used for the systematic
troubleshooting of faults with fault codes.
While trying to establishes the fault causes, you should always also
check the contacts of all electrical plug-and-socket connections
and the connection plugs in the UBA 3.
WARNING!
Danger to life due to electric shock.
 Switch off the Logamax plus GB142 when
testing the connections!
Whenever a fault has been remedied, you must press the "Reset"
button (for at least 5 seconds) to reset the UBA 3 to its setting
status (release).
NOTE!
Resetting is not possible by switching off the
operating switch!
If a fault is displayed again, you should follow the relevant structural
diagram to carry out further troubleshooting.
Certain trouble-shooting activities have to be carried out in the
heating mode of the Logamax plus GB142. The flue gas test or the
service mode must be activated then, see chapter „4 Operation“ on
page 9, "Flue gas test" menu on page 10 and "Service Mode"
menu on page 11.
Locking boiler-fault code - (dash)

No communication between UBA 3 and
BC10.

Other display code.

Press the "Reset" button.

New
fault message
?

Yes

44
page 83

8
page 31

Operating code -A

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

L
o
c

276

The supply sensor has measured a
temperature higher than 203 °F (95 °C).

k
i
n
g

Locking boiler-fault code.

b
o
il
e

277

The safety sensor has measured a
temperature higher than 203 °F (95 °C).

r
f
a
u

Locking boiler-fault code.

lt
c
o

2 85

The return sensor has measured a
temperature higher than 203 °F (95 °C).

d
e
1
L

Locking boiler-fault code.

(
fl
a
s
h
i
n
g
)
B
l
o
c
k
i
n
g
b
o
il
e
r
f

Wait approx. 60 seconds until the boiler
automatically becomes operational again.

fault message 0 Y ?

a
u
lt
c
o

Yes
Are all servicing cocks
open?

Open the servicing cocks.

Yes
Is the
system pressure (measured on the boiler)
in the heating system at least
14.5 psi (1 bar)?

Fill and bleed the heating system.

Yes
Is at least
one thermostatic valve open?

Open a thermostatic valve.

Yes
Check the supply, safety and return sensors
(page 89).

Are the supply and safety
sensors okay?

Replace the supply, safety and/or return
sensors (page 91).

Replace the primary
circulation pump.

Yes
Check the primary
circulation pump.

Is the primary circulation
pump okay?
Yes

44
page 83

8
page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

de 2E

21 1

The UBA 3 does not register any connections
to the unused contacts 78 and 50.

Locking boiler-fault code.

Check the contact between the UBA 3
and the UBA 3 mounting base.
See page 125, fig 109.

Is the contact
okay?

Restore the contact between the UBA 3 and
the UBA 3 mounting base.
See page 125, fig 109.

Yes
Try to remedy the fault by replacing the entire
cable loom.

Has the malfunction been repaired?

Yes

2 07

page 83

page 31

The system pressure is too low.

Is the pressure
in the heating system at least
14.5 psi (1 bar)?

Locking boiler-fault code.

Fill and bleed the heating system.

Yes
Replace the pressure sensor to test whether
the fault can be traced back to the sensor.
See page 116.

Is the
blocking boiler-fault code
cleared from the display?

Yes

page 83

page 31

Operating code 2F

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Blocking boiler-fault code 2F

260

No temperature increase after burner start or
the temperature difference between the supply
and safety sensors is more than 27 °F (15 K).

Operating code

271

The temperature difference between the supply
and safety sensors is more than 27 °F (15 K).

Locking boiler-fault code.

Wait approx. 60 seconds until the boiler
automatically becomes operational again.

fault message 2 F ?

Yes
Are all servicing cocks
open?

Open the servicing cocks.

Yes
Is the
system pressure (measured on the boiler)
in the heating system at least
14.5 psi (1 bar)?

Fill and bleed the heating system.

Yes
Is at least
one thermostatic valve open?

Open a thermostatic valve.

Yes
Check the supply and safety sensors
(page 89).

Are the supply and safety
sensors okay?

Replace the supply and/or safety sensors
(page 91).

Replace the primary
circulation pump.

Yes
Check the primary
circulation pump.

Is the primary circulation
pump okay?
Yes

page 83

page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Locking boiler fault code 2L

2 66

The primary circulation pump does not
generate a pressure difference.

Locking boiler-fault code.

Check the primary circulation pump for
mechanical jamming.

Is the primary circulation pump
jammed?

Yes

Try to undo the jam or replace the primary
circulation pump.

No
Does the primary circulation
pump run during 2 L ?

Yes

22
page 51

Check the primary circulation pump
activation.

Is the activation okay?

Yes

Replace the primary circulation pump.

No
Check the primary circulation pump; check
that the supply cord is not broken.

Is the supply cord okay?

Replace the supply cord.

Yes

page 83

page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Locking boiler fault code 2L TT

page 50

22
Check the primary circulation pump for
soiling.

Is the primary circulation pump
soiled?

Yes

Clean the circulation pump (inside).

No
Is the expansion
tank correctly connected to
the supply conduit?

Yes

Connect the expansion tank to the return
conduit.

No
Check whether the pressure sensor is soiled.
See page 116.

Is the pressure sensor
soiled?

Yes

Clean the pressure sensor.

No
Replace the pressure sensor.
See page 116.

Has the malfunction been
repaired?

Yes

page 83

page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Operating code 2P

21 2

Temperature increase of supply sensor or safety
sensor is more than 7.5 °F/sec (5 K/sec).

Operating code

Wait approx. 30 seconds until the boiler
automatically becomes operational again.

fault message

2P ?

Yes
Are all servicing cocks
open?

Open the servicing cocks.

Yes
Is the pressure
in the heating system (measured on
the boiler) at least
14.5 psi (1 bar)?

Fill and bleed the heating system.

Yes
Is at least
one thermostatic valve open?

Open a thermostatic valve.

Yes
Check the supply and safety sensors
(page 89).

Are the supply and safety
sensors okay?

Replace the supply and/or safety sensors
(page 91).

Replace the primary
circulation pump.

Yes
Check the primary
circulation pump.

Is the primary circulation
pump okay?
Yes

8
page 31

page 83

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Operating code 2U

21 3

The temperature difference between the supply
and return sensors is more than 90 °F (50 K).

Operating code

Wait approx. 30 seconds until the boiler
automatically becomes operational again.

fault message 2 U ?

Yes
Are all servicing cocks
open?

Open the servicing cocks.

Yes
Is at least
one thermostatic valve open?

Open a thermostatic valve.

Yes
Check the supply and return sensors
(page 89).

Are the supply and return
sensors okay?

Replace the supply and return sensors
(page 91).

Replace the primary
circulation pump.

Yes
Check the primary
circulation pump.

Is the primary circulation
pump okay?
Yes

8
page 31

page 83

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Blocking boiler-fault code 3A

264

The air fan has failed during the operating
phase.

Locking boiler-fault code.

Check that both the plug-and-socket
connections of the blower are correctly fitted.
See page 88, fig 12.

Are the plug-and-socket
connections fitted correctly?

Reconnect the plug-and-socket connection of
the blower. See page 88, fig 12.

Yes
Check blower – activation 120V AC
See page 86.

Is the activation okay?

23
page 55

Yes
Check the tacho wire of the blower.
See page 88.

Tacho wire okay?

Replace the tacho wire (page 88).

Yes
Check whether you can remedy the fault by
temporarily fitting a new blower.
See page 88, paragraph 8.1.6.

Has the malfunction been repaired?

Yes

No
Check that the mains voltage is
120V AC.

Sufficient mains voltage?

Have the electrical system tested.

Yes

page 83

page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Blocking boiler fault code 3A-2Blocking boiler fault code 3F

page 54

23
Check the supply cord of the blower
(120V AC). See page 87.

Is the supply cord okay?

Replace the supply cord.

Yes

page 31

page 83

273

The blower is switched off during the safety
test.

Locking boiler-fault code.

Fully switch off the heat request and check
that the blower is still operational after
1 minute.

Is the blower
still operational?

Yes

page 83

page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Locking boiler fault code 3L

21 4

The blower is switched off during the safety
test.

Locking boiler-fault code.

Check that both the plug-and-socket
connections of the blower are correctly fitted.
See page 88, fig 12.

Are the
plug-and-socket connections fitted
correctly?

Reconnect the plug-and-socket connection of
the blower. See page 88, fig 12.

Yes
Check blower – activation 120V AC.
See page 86.

Is the activation okay?

24
page 57

Yes
Check the tacho wire of the blower.
See page 88.

Tacho wire okay?

Replace the tacho wire. See page 88.

Yes
Attempt to rectify the fault by temporarily
replacing the blower.
See page 88.

Has the malfunction been repaired?

Yes

44
page 83

8
page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Locking boiler fault code 3L-2

page 56

24
Check the supply cord of the blower
(120V AC). See page 87.

Is the supply cord okay?

Replace the supply cord.

Yes

page 83

page 31

21 6

The blower is running too slowly.

Locking boiler-fault code.

Check to see if the blower
is soiled or wet.

Is the blower dry and
clean?

Clean or replace the blower.
See page 88.

Yes
Check that the mains voltage is
120V AC.

Sufficient mains voltage?

Have the electrical system tested.

Yes
Try to remedy the fault by integrating another
provisional blower. See page 88.

Has the malfunction been repaired?

Yes

page 83

page 31

Locking boiler-fault code 3P (flashing)

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Locking boiler-fault code 3Y (flashing)

21 5

The blower is running too fast.

Locking boiler-fault code.

Check the plug-and socket connection of the
tacho wire to the blower. This is the thin plug.
See page 88, fig 12.

Is the plug-and-socket
connection okay?

Restore the plug-and-socket connection.

Yes
Check the tacho wire by measuring the
resistance (is the wire broken?).
See page 88.

Tacho wire okay?

Replace the tacho wire.

Yes
Check that the mains voltage is
120V AC.

Sufficient mains voltage?

Have the electrical system tested.

Yes
Check that there is no blockage in the blower
or the heat exchanger and that the flue-gas
system is connected.
Yes

Did you find a
blockage?

Deal with blockage.

No
Check to see if there is a second blower in the
flue gas outlet conduit or air inlet system.
Is a second
blower fitted?

Yes

Take the second blower out of service.

No
Replace the blower.
See page 88, par. 8.1.6.

Check to see if the blower wheel has come
loose at the motor spindle.

Blower wheel loose?

Yes

No
Attempt to rectify the fault by temporarily
fitting another blower. See page 88.

Has the malfunction been repaired?
No

Yes

8
page 83

page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Locking boiler fault code 4A

21 8

The supply sensor has measured a
temperature higher than 221 °F (105 °C).

Locking boiler-fault code.

286

The return sensor has measured a
temperature higher than 221 °F (105 °C).

Locking boiler-fault code.

Press the "Reset" button.

New fault message
C A 4A ?

Yes
Are all servicing cocks
open?

Open the servicing cocks.

Yes
Is the
system pressure (measured on the
boiler) in the heating system at least
14.5 psi (1 bar)?

Fill and bleed the heating system.

Yes
Is at least
one thermostatic valve
open?

Open a thermostatic valve.

Yes
Check the primary
circulation pump.

Is the primary circulation
pump okay?

Replace the primary
circulation pump.

Yes
Check the supply or return sensor (page 89).

Are the supply and
return sensors okay?

Replace the supply and return sensor
(page 91).

Yes

page 83

page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Locking boiler-fault code 4C (flashing)Locking boiler-fault code 4E (flashing)

224

The UBA 3 does not register the short cut
bestween the unused contacts 22 and 24.

Locking boiler-fault code.

Check the contact between the UBA 3
and the UBA 3 mounting base.
See page 126, fig 110.

Is the contact okay?

Restore the contact between the UBA 3 and
the UBA 3 mounting base.
See page 125, fig 109.

Yes
Try to remedy the fault by replacing the entire
cable loom.

Has the malfunction been repaired?

Yes

page 83

page 31

27 8

The sensor test has failed.

Locking boiler-fault code.

Measure the voltage to check for a possible
short circuit in the supply or safety sensor
wiring. See page 126.

Is the wiring
okay?

Replace the cable loom or the affected part
thereof.

Yes

page 83

page 31

Locking boiler-fault code 4E (flashing)

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Locking boiler fault code 4L

220

The safety sensor is shorted or measures
temperatures higher than 266 °F (130 °C).

Locking boiler-fault code.

Press the "Reset" button.

New fault message

4L ?

Yes
Are all servicing cocks
open?

Open the servicing cocks.

Yes
Is the pressure in the
heating system at least
14.5 psi (1 bar)?

Fill and bleed the heating system.

Yes
Is at least
one thermostatic valve
open?

Open a thermostatic valve.

Yes
Check the primary
circulation pump.

Is the primary circulation
pump okay?

Replace the primary
circulation pump.

Yes
Check the wire to the safety sensor for signs
of short circuiting (page 92).

Is the wire okay?

Replace the cable loom or the affected part
thereof.

Yes

page 62

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Locking boiler fault code 4L-2

page 61

Check the safety sensor (page 89).

Is the safety sensor okay?

Replace the safety sensor (page 91).

Yes

page 83

page 31

221

The safety sensor contact is interrupted.

Locking boiler-fault code.

Press the "Reset" button.

New fault message

4P ?

Yes
Check the wire to the safety sensor for the
correct contact (page 92).

Is the wire okay?

Replace the cable loom or the affected part
thereof.

Yes
Check the safety sensor (page 89).

Is the safety sensor okay?

Replace the safety sensor (page 91).

Yes

page 83

page 31

Locking boiler fault code 4P

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Locking boiler fault code 4U

222

The supply sensor contact is shorted.

Locking boiler-fault code.

240

The return sensor contact is shorted.

Locking boiler-fault code.

Press the "Reset" button.

New fault message
4 U or C U ?

Yes
Check the wire to the supply or return sensor
for signs of short circuiting (page 92).

Is the wire okay?

Replace the cable loom or the affected part
thereof.

Replace the supply and return sensor
(page 91).

Yes
Check the supply and return sensor
(page 89).

Are the supply and return
sensors okay?
Yes

44
page 83

8
page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Locking boiler fault code 4Y

223

The supply sensor contact is interrupted.

Locking boiler-fault code.

241

The return sensor contact is interrupted.

Locking boiler-fault code.

Press the "Reset" button.

New fault message
4Y or C Y ?

Yes
Check the wire to the supply or return sensor
for the proper contact (page 92).

Is the wire okay?

Replace the cable loom or the affected part
thereof.

Yes
Check the supply and return sensor
(page 89).

Are the supply
and return sensors okay?

Replace the supply and return sensor
(page 91).

Yes

44
page 83

8
page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Locking boiler fault code 6A

227

No ionization after four startup attempts.

Locking boiler-fault code.

page 71

Press the "Reset" button.

New fault message

6A ?

Yes
Is the
heating system propane
gas-fired?
No

Yes

Contact the gas utility company to ensure that
no nitrogen remains in the gas tank or gas
supply pipes.

Measure the static inlet gas pressure.
See page 107.

Is the
inlet gas pressure
okay?

page 68

Yes
Bleed the gas supply pipe. See page 106.

Has the gas supply pipe
been bled of air?

No
Bleed the gas supply pipe. See page 106.

Yes
Check the hot surface ignitor is activated
during the operating code 0 C .
See page 92.

Is the
hot surface ignitor activated
during the operating
code 0 C .

page 68

Yes
Check the resistance of the hot surface
ignitor. See page 93.

Is the resistance of the
hot surface ignitor
okay?

Replace the hot surface ignitor.
See page 94.

Yes

page 66

page 71

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Locking boiler fault code 6A -2

page 65

Check the hot surface ignitor glows
during the operating code 0 C .
See page 92.

Does the
hot surface ignitor activated
glow during the operating
code 0 C ?
Yes

Replace the hot surface ignitor.
See page 94.

Check the gas valve is opened during the
operating code 0 L .
See page 98.

Is the gas valve
open?

page 69

page 70

Yes
Measure the dynamic inlet gas pressure.
See page 107.
Is the
dynamic inlet gas pressure
okay?

Yes
Measure the gas/air ratio during the startup
phase. See page 108.

Is the gas/air ratio correctly
adjusted?

Adjust the gas/air ratio.
See page 108.

Yes
Check that the correct gas orifice was fitted.
See page 127, table 5.

Was the
correct gas orifice
fitted?

Fit the correct gas orifice.
See page 127, table 5.

Yes

page 67

page 71

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Locking boiler fault code 6A -3

page 66

34
Check the following elements for soiling,
damage and correct assembly:
-

the combustion-air inlet conduit
the air suction tube
the seal between the Venturi and the blower
the gas orifice, see page 101 and
page 127, table 5
the blower, see page 86
the connection between the blower and the
burner
the burner
the heat exchanger, see page 117
the flue gas conduit.

Are the abovementioned components clean and
free from damage?

Clean and/or replace the corresponding
components.

Yes
Measure the ionization current.
See page 95.
No
Is the ionization current
okay?

page 71

Yes

31
page 71

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

vorh6A Branch 036A Branch 04

page 65

Check whether the gas stop tap is open.
See page 101.
No

Is the gas stop tap open?

Open the gas stop tap. See page 101.

Yes
Check to see if there is a blockage in the
conduit between the gas stop tap and gas
valve.
Yes

Did you
find a blockage?

Deal with blockage.

No
Check for blockages in the remaining section
of the gas supply pipe.

Did you
find a blockage?

Yes

Deal with blockage.

No
If the required inlet gas pressure is not
available, you should consult your gas utility
company.

31
page 71
page 65

29
Measure the resistance in the wires between
the switch of the hot surface ignitor and the
UBA 3. See page 99.

Is the wiring okay?

Replace the cable loom or the affected part
thereof.

Yes

page 83

page 71

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

6A Branch 05 v1 v8

page 66

Check the plug-and-socket connection of the
gas valve. See page 99.

Is the plug-and-socket
connection okay?

Reconnect the plug-and-socket connection at
the gas valve. See page 99.

Yes

Replace the gas valve.
See page 101.

Replace the cable loom or the affected part
thereof.

Yes
Check the gas valve during the
operating code 0 L to make sure it receives
power then. See page 98.

Does the gas valve receive power?
No
Measure the resistance in the wires between
the gas valve plug and
the UBA 3 mounting base.

Is the wiring okay?
Yes

page 83

page 71

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

6A Branch 06

page 66

Check whether the gas stop tap is open.
See page 101.

Is the gas stop tap open?

Open the gas stop tap. See page 101.

Yes
Check for blockages in the remaining section
of the gas supply pipe.

Did you find a blockage?

Yes

Deal with blockage.

No
Check for blockages in the remaining section
of the gas supply pipe.

Did you find a blockage?

Yes

Deal with blockage.

No
Check whether the overall gas-conduit
network is of sufficient capacity.

Is the overall gas-conduit
network of sufficient capacity?

Reinforce the gas-conduit network.

Yes
Consult the utility
company.

31
page 71

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

6A Branch 07

page 67

35
Check the plug-and-socket connection
between the ionization electrode and cable
loom. See page 95.

Is the plug-and-socket
connection okay?

Correctly insert the plug into its socket.

Yes
Measure the resistance in the wires between
the ionization electrode plug and the UBA 3
mounting base. See page 95.

No
Is the wiring okay?

Replace the cable loom or the affected part
thereof.

Yes
Check the ionization electrode and replace it
if necessary. See page 97

31
page 71
pages 65 to 71

Press the "Reset" button.

Has a new fault code
occurred?

Yes

Has a new locking boiler fault
code 6 A occurred?

Remedy the fault using the structure diagram
that corresponds with the fault code.

Yes
Did you
go through all structure diagrams
thru 35 ?

27
page 65

Yes

page 83

page 31

6A Branch 08

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Locking boiler fault code 6C

An ionization current was measured before
the burner start.

228

Locking boiler-fault code.

Press the "Reset" button.

New fault message

Yes
Check the ionization electrode for soiling.
Damage see page 95.

Is the ionization electrode
okay?

Replace the ionization electrode.
See page 97.

Yes

page 72

page 31

306

An ionization current was measured after the
burner switch-off.

Locking boiler-fault code.

Check that the burner is still under pressure
after the heat request has ended.
See page 108, par. 8.1.26.

Is the burner still under
pressure?

Yes

Replace the gas valve.
See page 101.

44
page 77

8
page 31

Locking boiler fault code 6C-2

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Blocking boiler-fault code 6L

229

Ionization fails during the operating phase.

Is the
heating system propane
gas-fired?

Yes

Locking boiler-fault code.

Ensure that no nitrogen remains in the gas
tank or gas supply pipes, in close consultation
with the gas utility company.

No
Measure the static inlet gas pressure.
See page 107.

Is the static inlet gas pressure okay?

page 75

Yes
Bleed the gas supply pipe. See page 106.

Has the gas supply pipe
been bled of air?

No
Bleed the gas supply pipe. See page 106

Yes
Measure the dynamic inlet gas pressure.
See page 107.
Is the
dynamic inlet gas pressure
okay?

page 76

Yes
Measure the gas/air ratio during the startup
phase. See page 108.
No
Is the gas/air ratio correctly
adjusted?

Adjust the gas/air ratio.
See page 108.

Yes

page 74

page 77

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Blocking boiler-fault code 6L - 2

page 73

Check that the correct gas orifice was fitted.
See page 127, table 5.

Was the
correct gas orifice
fitted?

Fit the correct gas orifice.
See page 127, table 5.

Clean and/or replace the corresponding
components.

Yes
Check the following elements for soiling,
damage and correct assembly:
-

Are the abovementioned components clean and
free from damage?
Yes
Measure the ionization current.
See page 95.

Is the ionization current
okay?

page 77

Yes

41
page 77

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Blocking boiler-fault code 6L - br12

page 73

Check whether the gas stop tap is open.
See page 101.

Is the gas stop tap
open?

No
Open the gas stop tap. See page 101.

Yes
Check to see if there is a blockage in the gas
conduit section between the gas stop tap and
gas valve.

Did you find a blockage?

Yes

Deal with blockage.

No
Check for blockages in the remaining section
of the gas supply pipe.

Did you find a blockage?

Yes

Deal with blockage.

No
If the required inlet gas pressure is not
available, you should consult the relevant
gas utility company.

41
page 77

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Blocking boiler-fault code 6L branch 13

page 73

Check whether the gas stop tap is fully open.
See page 101.

Is the gas stop tap
fully open?

Open the gas stop tap. See page 101.

Yes
Check to see if there is a blockage in the gas
conduit section between the gas stop tap and
gas valve.

Did you find a blockage?

Yes

Deal with blockage.

No
Check for blockages in the remaining section
of the gas supply pipe.

Yes
Did you find a blockage?

Deal with blockage.

No
Check whether the overall gas-conduit
network is of sufficient capacity.

Is the overall gas-conduit
network of sufficient capacity?

Reinforce the gas-conduit network.

Yes
Consult the gas utility company.

41
page 77

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Blocking boiler-fault code 6L branch 14

page 74

Check the plug-and-socket
connection between the ionization electrode
and cable loom. See page 95.

Is the plug-and-socket
connection okay?

Correctly insert the plug into its socket.

Replace the cable loom or the affected part
thereof.

Yes
Measure the resistance in the wires between
the ionization electrode plug and the UBA 3
mounting base. See page 99.

Is the wiring okay?
Yes
Replace the ionization electrode.
See page 97

41
page 77
page 73 – page 77

Press the "Reset" button.

Has a new fault code
occurred?

Yes

Has a new locking boiler fault
code 6 L occurred?

Remedy the fault using the structure diagram
that corresponds with the fault code.

Yes
Did you
go through all structure diagrams
thru 14?
Yes

44
page 29

page 83

page 31

locking boiler fault code 6L Zijtak 1e 5

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Locking boiler-fault code 6P (flashing)

269

The hot surface ignitor activates too long.

Locking boiler-fault code.

Press the "Reset" button.

Has the malfunction been repaired?

KIM defective, contact the Buderus customer
service department. See on the back side of
this document.

Yes

8
page 31

23 1

The power supply was interrupted
after a fault message.

Locking boiler-fault code.

Press the "Reset" button.

Has a new fault code
occurred?

Yes
Remedy the fault using the structure diagram
that corresponds with the fault code.

8
page 31

Locking boiler-fault code 7C Locking boiler-fault code 7L (flashing)

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Operating code 8Y

261

The UBA 3 is defective.

Locking boiler-fault code.

280

The UBA 3 is defective.

Locking boiler-fault code.

44
page 83

232

The external switch contact is activated.

Locking boiler-fault code.

Check that the switch contact is
connected to the boiler.
See page 106, fig. 54, pos. 5 "EV".

Is an external switch
contact connected?

43
page 80

Yes
Check to see if an external switch contact
is open, by measuring its resistance using a
volt-ohm-multimeter

Is the external switch
contact open?

Yes

External switch contact has energized.

No
Measure the cable loom between the UBA 3
and the terminal strip.
See page 126, fig 110.

Is the cable loom okay?

Replace the cable loom or the affected part
thereof.

Yes
Check the contact between the UBA 3
and the UBA 3 mounting base.

Is the contact okay?

Restore the contact.

Yes

page 83

page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Operating code 8Y dl 2

page 79

43
Check to see if a bridge wire is present.
See page 106, fig. 54, pos. 5 "EV".

Is there a bridge wire?

Restore the bridge on the terminal strip again
(see page 106, fig. 54).

Replace the cable loom or the affected part
thereof.

Yes
Measure the cable loom between the UBA 3
and the terminal strip.
See page 126, fig 110.

Is the cable loom okay?
Yes
Check the contact between the UBA 3 and
the UBA 3 mounting base.

Is the contact okay?

Restore the contact.

Yes

page 83

page 31

23 5

KIM or UBA 3 is defective.

Locking boiler-fault code.

23 7

KIM or UBA 3 is defective.

Locking boiler-fault code.

23 9

KIM or UBA 3 is defective.

Locking boiler-fault code.

23 3

KIM or UBA 3 is defective.

Locking boiler-fault code.

KIM or UBA 3 is defective.

Locking boiler-fault code.

The UBA 3 is defective.

Locking boiler-fault code.

E
E

+ any digit or letter

242

+ any digit or letter

287

290

Press the "Reset" button.
New
fault message 9 A or

9 H or 9 P or 9 U or E ?
Yes

page 83

page 31

Locking boiler fault codes 9A, 9H, 9P, 9U, E

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Locking boiler fault code 9L

23 4

The gas valve coil or the wiring to the gas
valve is defective.

Locking boiler-fault code.

23 8

The UBA 3 is defective.

Locking boiler-fault code.

Press the "Reset" button.

New fault message 9 L ?

Yes
Check the plug-and-socket connection of the
gas valve. See page 98, par. 8.1.18.

Is the plug-and-socket
connection okay?

Restore the plug-and-socket connection.
See page 98, par. 8.1.18.

Replace the cable loom or the affected part
thereof.

Replace the gas valve.
See page 101.

Yes
Measure the wire between the gas valve
and the UBA 3.
See page 99, fig 8.1.20.

Is the wire okay?
Yes
Measure the resistance of the two gas valve
coils. See page 101, par. 8.1.22.

Is the resistance correct?
Yes

page 83

page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Locking boiler fault code H 7/P--

288

The UBA 3 has no connection to the pressure
sensor or there is a short circuit.

Locking boiler-fault code.

289

Short circuit in connection to pressure sensor.

Locking boiler-fault code.

Check the plug-and socket connection of the
pressure sensor. See page 8, fig. 1, pos. 17.

Is the plug-and-socket
connection okay?

Restore the plug-and-socket connection.

Yes
Check the wiring between the pressure
sensor and the UBA 3 mounting base by
measuring the resistance (fracture).
See page 126, fig 110.

Is the wiring okay?

Replace the cable loom or the affected part
thereof.

Yes
Try to remedy the fault by integrating
another provisional pressure sensor.
See page 116.

Has the malfunction been repaired?

Yes

page 83

page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Diagnosis

Replace the UBA

Check the contacts between the UBA 3 and
the UBA 3 mounting base, between the BC10
and the base plate and all other plug-andsocket connections.
See from page 92.
Remedy contact faults.
See from page 92.

Press the "Reset" button and hold it for
2 seconds. See page 9.
Replace the UBA 3. See page 125.
No
Is the same fault message
displayed?

Yes

Has the UBA 3 already
been replaced?

Yes
Call the Buderus customer service department.
See on the back side of this document.

Has a new fault occurred?

Yes

Remedy the fault using the structure diagram
from this document that corresponds with the
fault code.

8
page 31

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions

8.1

Testing, measuring, adjusting and replacing
various components

8.1.1

Checking the UBA 3 fuse; replace if necessary
2

 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Loosen the fastening screw of the UBA 3 by turning it counterclockwise (see fig. 4, pos. 1).
WARNING!
Do not pull or move side to side the UBA 3
during loosening or tightening of UBA 3 fastening
screw.
 Remove the UBA 3 once the fastening screw is fully loosened
by pulling it forward carefully as indicated by the arrow (see
fig. 4, pos. 2).

 Dismantle the fuse holder by loosening the bayonet connector
(see fig. 5, pos. 1).

fig. 4

 Remove the fuse from the fuse holder.

Dismantling the UBA 3

 Check the circuit continuity through the fuse using the volt-ohmmultimeter. If broken, replace it by (a new) spare ceramic fuse
5 amps, 250V fast blow (F5AH, 250V) (fig. 5, pos. 2).

 Re-assemble the UBA 3 in reverse order of disassembly.
 Fasten the UBA 3 by only turning the fastening screw clockwise.
WARNING!
Do not push or force the UBA 3 in place by hand.

 Fit the casing.

fig. 5

Checking the fuses

 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions
8.1.2

External connection board fuse

 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Remove the cover from the connection box (fig. 6).

fig. 6

Removing the cover from the connection box

 Dismantle the fuse holder (fig. 7, pos. 10).
 Remove the fuse from the fuse holder.
 Check the circuit continuity through the fuse using the volt-ohmmultimeter. If broken, replace it with a (new) ceramic fuse
5 amps, 250V fast blow (F5AH, 250V).
 Re-install the cover on the connection box.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).

11
PK

Grid

RC FA WA FW EV

1
fig. 7

External connection board

pos. 1: RC Room thermostat (connection color orange)
pos. 2: Outdoor-temperature sensor (connection color
blue)
pos. 3: Potential-free On/Off thermostat (connection color
green)
pos. 4: DHW temperature sensor (connection color grey)
pos. 5: External switching contact, potential-free for floor
heating safety etc. (connection color red)
pos. 6: DO NOT USE
pos. 7: Primary loop pump 120V 60Hz (connection color
green)
pos. 8: DHW tank pump 120V 60Hz (connection color grey)
pos. 9: DHW recirculating pump 120V 60Hz (connection
color lilac)
pos. 10: main connection 120V 60Hz (connection color
white)
pos. 11: Fuse holder

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

8
8.1.3

Actions
Checking the fan unit; 120 VAC control
NOTE
The fan unit can be controlled using the RC control
device relay test function. Further instructions for
the RC control device are in the Installation and
Maintenance Instructions.
WARNING!
Avoid damage: do not push the measuring pin of
the volt-ohm-multimeter too deeply into the socket.

 Remove the casing.
 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Disconnect the 120V AC plug of the fan unit.
 Test the voltage with the volt-ohm-multimeter; set it to VAC.
Minimum value 250V AC.

fig. 8

Checking for 120V AC voltage

 Connect the volt-ohm-multimeter to the outer two plug contacts
(blue and brown) (see fig. 8).
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).
 Start up the boiler in accordance with the "Flue gas test" menu.
See page 10 "Flue gas test" menu.
 Check that while the operating code [0/l/\| is displayed,
120V AC is available on the outer two contacts (blue and
brown) of the plug (see fig. 8).
 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Reconnect the plug to the fan unit.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions
8.1.4

Checking the fan unit; supply cord (120V AC)
WARNING!

Avoid damage: do not push the measuring pin of
the volt-ohm-multimeter too deeply into the socket.
 Remove the casing.
 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Disconnect the 120V AC plug of the fan unit.
 Loosen the fastening screw of the UBA 3 (see fig. 9, pos. 1).
 Remove the UBA 3 by pulling it forward as indicated by the
arrow (see fig. 9, pos. 2).

 Set the volt-ohm-multimeter to "Resistance testing".
fig. 9

Dismantling the UBA 3

fig. 10

UBA 3 installation base

Pin 1
28
55

 Reconnect the plug to the fan unit.
 Re-assemble the UBA 3 in reverse order of disassembly.

Pin 16

 Test the fan unit supply cord to make sure that there is no short
circuit in it and that it is not broken anywhere (see fig. 10 and
fig. 110 on page 126).

81-pole connector

 Set the main switch on the BC10 to "1" (On).

16-pole connector

 Switch on the power supply of the heating system on the circuit
breaker.

Pin 1

Pin 81

KIM

 Fit the casing.

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Checking the fan unit; tacho cable

Pin 16

WARNING!

81-pole connector

16-pole connector

KIM

 Loosen the fastening screw of the UBA 3 (see fig. 9, pos. 1).

Pin 81

 Remove the UBA 3 by pulling it forward as indicated by the
arrow (see fig. 9, pos. 2).
 Test the tacho cable to make sure that there is no short circuit
in it and that it is not broken (see fig. 11).
 Assemble the tacho cable plug.

fig. 11

Pin 1

8.1.5

Actions

Pin 1
28
55

UBA 3 installation base

 Re-assemble the UBA 3 in reverse order of disassembly.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).
8.1.6

Replacing the fan unit
NOTE
Follow the installation instructions for 120V fan
units!

 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Remove both cable plugs from the fan unit
(see fig. 12, pos. 1).

fig. 12

Disconnect the cable plug from the fan unit

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions

 Remove the air suction tube (see fig. 13, pos. 1).
 Remove the fan unit fastening screw (see fig. 13, pos. 2).
 Remove the fan unit by swinging it to the right
(see fig. 13, pos. 3).
 Install the new fan unit.
 Install the fastening screw, air suction tube and both plugs.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).

fig. 13
8.1.7

Dismantling the fan unit

Checking the supply/return/safety/hot-water temperature sensors
NOTICE
The current temperature measured by the supply,
return and safety sensors, can be read out from the
RC control device.
For further instructions, see installation and maintenance instructions of the RC control device.

WARNING!

Avoid damage: do not push the measuring pin of
the volt-ohm-multimeter too deeply into the socket.
 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.

fig. 14

Checking the supply/return sensors

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions

 Disconnect the plug and socket connection of the cable for the
sensor concerned.
 Test the resistance of the sensor concerned.
Supply sensor see fig. 14, pos. 1.
Return sensor see fig. 14, pos. 2.
Safety sensor see fig. 15, pos. 1.

 Measure the temperature near the sensor using a seconds
thermometer.
 Compare the values measured to the values in table 4 on the
next page. If the values differ, the sensor is broken.
 Reconnect the plug and socket connection if the sensor is OK.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).

fig. 15

Checking the safety sensor
Temperature in
°F

°C

29,490

23,462

18,787

15,136

12,268

10,000

8,197

6,754

104

5,594

113

4,656

122

3,893

131

3,271

140

2,760

149

2,339

158

1,990

167

1,700

176

1,458

185

1,255

194

1,084

203

940

212

100

817

table 4

Resistance in

Sensor resistance values (target values)

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions
8.1.8

Replacing the supply/return/safety sensors

 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
1

 Remove the casing.
 Close the maintenance shut-off valves.
 Drain the Logamax plus GB142.
 Disconnect the plug and socket connection.

 Unscrew the sensor concerned and replace it by a new one.
Supply sensor see fig. 16, pos. 1.
Return sensor see fig. 16, pos. 2.
Safety sensor see fig. 17, pos. 1.
 Restore the plug and socket connection.
 Open the maintenance shut-off valves.
 Purge air from the boiler.
fig. 16

Replacing the supply/return sensors

NOTICE
Fill and purge the Logamax plus GB142 as
required. See installation and maintenance instructions Logamax plus GB142-24/30/45/60.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.

 Set the main switch on the BC10 to "1" (On).
8.1.9

Checking the hot-water temperature sensor

fig. 17

Replacing the safety sensor

 Pull out the sensor and replace it by a new one.
 Restore the plug and socket connection.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

8
8.1.10

Actions
Checking the supply/return/safety sensors cable
WARNING!

Avoid damage: do not push the measuring pin of
the volt-ohm-multimeter too deeply into the socket.
 Check all plug and socket connections of the sensors and the
UBA 3. A plug that has not been inserted correctly may be the
cause for a fault message. Then start the boiler by pressing
"Reset" c.
 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Loosen the fastening screw of the UBA 3 (see fig. 18, pos. 1).
 Remove the UBA 3 by pulling it forward as indicated by the
arrow (see fig. 18, pos. 2).
 Disconnect the plug and socket connection of the cable for the
sensor.

fig. 18

Dismantling the UBA 3

fig. 19

UBA 3 installation base

Pin 1
28
55

 Check the cable between the plug and socket connection and
the 81-pole plug in the UBA 3 installation base (see fig. 19)
using a circuit continuity testing device.
See the electric circuit diagram, fig. 110 on page 126.

Pin 16

 Remove the casing.

81-pole connector

 Restore the plug and socket connection if the cables are OK.

16-pole connector

 Test this in a straight line twice and test it diagonally twice.
 Install the UBA 3.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.

KIM

 Set the main switch on the BC10 to "1" (On).

NOTICE
The hot surface ignitor can be controlled using the
RC control device relay test function. Further
instructions for the RC control device are in the
installation and maintenance instructions.

Pin 1

Checking the hot surface ignitor; control
Pin 81

8.1.11

 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Disconnect the plug and socket connection of the hot surface
ignitor.
 Set the measuring device to 120V AC.
 Connect the measuring device to the plug on the cable
harness.
 Connect the heating system to the power supply, insert the
main fuse or switch on the circuit breaker.

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions

 Set the main switch on the BC10 to "1" (On).
 Start up the boiler in accordance with the "Flue gas test" menu.
See page 10 "Flue gas test" menu.
 Test that during the ignition phase, while the operating code
[0/l/\| is being displayed, 120V AC is measured.
 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the measuring device.
 Assemble the plug and socket connection of the hot surface
ignitor.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).

8.1.12

Checking the hot surface ignitor; resistance

 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Disconnect the plug and socket connection of the cable of the
hot surface ignitor.
 Test the resistance of the hot surface ignitor on the plug.
A resistance value between 50 – 300 Ω means that the hot
surface ignitor is OK (see fig. 20).
 Remove the measuring device.
 Reconnect the cable plug if the hot surface ignitor is OK.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).
fig. 20
8.1.13

Checking the hot surface ignitor; supply cord

Checking the hot surface ignitor
2

WARNING!
Avoid damage: do not push the measuring pin of
the volt-ohm-multimeter too deeply into the socket.
 Remove the casing.
 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Pull the plug of the hot surface ignitor.
 Loosen the fastening screw of the UBA 3 (see fig. 21, pos. 1).
 Remove the UBA 3 by pulling it forward as indicated by the
arrow (see fig. 21, pos. 2).
 Set the volt-ohm-multimeter to "Resistance testing".

fig. 21

Dismantling the UBA 3

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions

Pin 1
28
55

 Test the supply cord of the hot surface ignitor to make sure that
there is no short circuit in it and that it is not broken (fig. 23,
fig. 22 and fig. 110 on page 126).

Pin 1

Pin 81

KIM

81-pole connector

16-pole connector

Pin 16

fig. 22

UBA 3 installation base

fig. 23

Testing the supply cord of the hot surface ignitor

fig. 24

Replacing the hot surface ignitor

 Fit the plug to the hot surface ignitor.
 Re-assemble the UBA 3 in reverse order of disassembly.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).
 Fit the casing.

8.1.14

Replacing the hot surface ignitor

 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Disconnect the plug and socket connection of the cable of the
hot surface ignitor.
 Loosen the fastening screws (fig. 24, pos. 1).
 Remove the earth cable (fig. 24, pos. 2).
 Remove the mounting plate (fig. 24, pos. 3).
 Remove the hot surface ignitor (fig. 24, pos. 4).
 Install the new hot surface ignitor with a new gasket and attach
the mounting plate with fastening screws (see fig. 24, pos. 1).
 Restore the plug and socket connection of the hot surface
ignitor.
 Fit the casing.

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions

 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).
8.1.15

Testing the ionization current
WARNING!
Avoid damage: do not push the measuring pin of
the volt-ohm-multimeter too deeply into the socket.

 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Disconnect the plug and socket connection of the monitoring
cable.
 Connect the measuring device in series (see fig. 25).
 Set the multi-meter to DC µA.
 Connect the heating system to the power supply, insert the
main fuse or switch on the circuit breaker.
 Set the main switch on the BC10 to "1" (On).

fig. 25

Testing the ionization current

 Start up the boiler in accordance with the "Service Mode" menu.
See page 11 "Service Mode" menu.
 Test the ionization current at partial load. The boiler is in partload operation as soon as, in the "Service Mode" menu, [l/3/0|
is selected. The ionization current must be > 1.4 DC µA.
 Remove the measuring device.
 Reconnect the plug and socket connection of the monitoring
cable if the ionization current is OK.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).

8.1.16

Checking the ionization electrode; cable

 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Dismantle the plug and socket connection of the
ionization electrode.
 Loosen the fastening screw of the UBA 3 (see fig. 26, pos. 1).
 Remove the UBA 3 by pulling it forward as indicated by the
arrow (see fig. 26, pos. 2).
1

fig. 26

Dismantling the UBA 3

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions

 Test the ionization cable between the plug and socket connection and the UBA 3 installation base to make sure that it has no
short circuit to earth (see fig. 27 and fig. 110 on page 126) and
that it is not broken anywhere (see fig. 28).
 Assemble the plug and socket connection of the ionization electrode.
 Re-assemble the UBA 3 in reverse order of disassembly.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).

Testing the earth connection circuit of the ionization
electrode (1)

Pin 16

UBA3

fig. 28

Pin 1

Pin 81

KIM

81-pole connector

16-pole connector

Pin 1
28
55

fig. 27

Testing the earth connection circuit of the ionization
electrode (2)

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions
8.1.17

Checking the ionization electrode; replace if
necessary

 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Disconnect the plug and socket connection of the cable.
 Set the volt-ohm-multimeter to "Resistance testing".
 Test the earth connection circuit of the ionization electrode (see
fig. 27). The height of the resistance value must be infinite.
 Loosen the fastening screws (see fig. 29, pos. 1).
fig. 29

Replacing the ionization electrode

fig. 30

Testing the resistance of the ionization electrode

fig. 31

Checking the ionization electrode

 Remove the earth cable (see fig. 29, pos. 2).
 Remove the mounting plate (see fig. 29, pos. 3).
 Dismantle the ionization electrode (see fig. 29, pos. 4).
 Set the volt-ohm-multimeter to "Resistance measurement".
 Test the resistance of the ionization electrode (see fig. 30).
The resistance must be 0 Ω.

 Check the ionization electrode for contamination, wear or
damage (see fig. 31).
 Replace the ionization electrode if required.
 Install a new ionization electrode with a new gasket and secure
the mounting plate with the fastening screws.
 Fit the earth cable (see fig. 29, pos. 2).
 Restore the plug and socket connection.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

8
8.1.18

Actions
Checking the gas control valve; cable connections

 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Check that the plug of the gas control valve has been installed
correctly (see fig. 32, pos. 1).
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).
1

8.1.19

fig. 32

Checking the cable connections to the gas control
valve (e.g. HONEYWELL gas control valve)

fig. 33

Voltage testing on the gas control valve

Checking the gas control valve; Control
NOTICE
You can drive the burner (the gas valve) using the
relay test in combination with the RC control
device. See installation and maintenance instructions of the RC control device.
WARNING!
Avoid damage: do not push the measuring pin of
the volt-ohm-multimeter too deeply into the socket.

 Remove the casing.
 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).
 Start up the boiler in accordance with the “Flue gas test” menu.
See page 10 "Flue gas test" menu.
 Use a volt-ohm-multimeter to check that, while operating code
[0/l/\| is displayed, there is a voltage on the plug of the gas
control valve. The test must indicate a voltage of 20 – 24 VDC
both when testing on the central and left contacts and when
testing on the central and right contacts (see fig. 33).
 Fit the casing.

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions
8.1.20

Checking the gas control valve; cable connection
between gas control valve and UBA 3 installation
base
WARNING!
Avoid damage: do not push the measuring pin of
the volt-ohm-multimeter too deeply into the socket.

 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Remove the plug of the gas control valve (see fig. 34).
fig. 34

Removing the gas control valve plug

 Loosen the fastening screw of the UBA 3 (see fig. 35, pos. 1).
 Pull the UBA 3 forward in the direction indicated by the arrow
(see fig. 35, pos. 2).

fig. 35

Dismantling the UBA 3

fig. 36

Testing the cable between the gas control valve and
the UBA 3 installation base

 Test the resistance of the cable between the plug of the gas
control valve and the UBA 3 installation base (see fig. 36,
fig. 37 and circuit diagram, fig. 110 on page 126).
 Reconnect the plug to the gas control valve (see fig. 34).
 Re-install the UBA 3 (see fig. 35).
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions

8.1.21

Pin 1

Pin 81

KIM

81-pole connector

16-pole connector

Pin 16

Pin 1
28
55

fig. 37

UBA 3 installation base

fig. 38

Removing the gas control valve plug

fig. 39

Testing the resistance on the gas burner ass’y (1)

Ohming out the gas control valve

 Test the resistance of both coils of the gas control valve using
the volt-ohm-multimeter. The resistance measured between
the left and central contacts (see fig. 39) must be approx. 75 Ω
and between the right and central contacts (see fig. 40) this
must be approx. 185 Ω (+/- 10 Ω). If this is not the case, the gas
control valve will probably be defective. It must then be
replaced.
 Attach the plug to the gas control valve.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).

100

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions

8.1.22

fig. 40

Testing the resistance on the gas burner ass’y (2)

fig. 41

Gas shut-off valve closed (1), gas shut-off valve
open (2)

fig. 42

Removing the gas control valve plug

Replacing the gas control valve
DANGER
Work on gas pipes and fittings must only be carried
out by a registered service provider.

 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Close the gas shut-off valve (see fig. 41, pos. 1).

 Remove the cable plug from the gas control valve (see fig. 42,
pos. 1).

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

101

Actions

 Remove both cable plugs from the fan unit (see fig. 43, pos. 1).

1
fig. 43

Disconnect the cable plug from the fan unit

 Loosen the union nut of the gas control valve (see fig. 44,
pos. 1).

1
fig. 44

Loosening the union nut

 Loosen both sets of retaining clips (fig. 44, pos. 2 and fig. 45,
pos. 1) of the burner cover and remove the burner cover with
the fan unit and the gas burner fitting.

1
fig. 45

102

Loosening the retaining clips

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions
 Loosen three screws on the gas control valve (see fig. 46,
pos. 1).

1
1

fig. 46

Loosening the screws

fig. 47

Dismantling the gas control valve

 Remove the gas control valve (see fig. 47).

 Remove the gas orifice from the gas control valve (see fig. 48,
pos. 1).
 Install the gas orifice in the new gas control valve.
 Mount the new gas control valve on the fan unit.
 Assemble the burner cover with the fan unit and the gas control
valve.
 Close both retaining clips.
 Tighten the union nut of the gas pipe on the gas control valve.
Make sure that you have inserted the gasket!
 Connect both cable plugs to the fan unit.
 Connect the cable plug to the gas control valve.
 Open the gas shut-off valve (see fig. 49, pos. 2).
 Switch on the power supply of the heating system on the circuit
breaker.

1
fig. 48

Dismantling the gas orifice

 Set the main switch on the BC10 to "1" (On).

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

103

Actions

NOTICE!
Carry out all start-up activities according to the
Installation and Servicing Instructions and
complete the start-up report.
You must also check all gaskets and seals affected by the replacement activities during the tightness test carried out in operating
conditions!
 Fit the casing.

8.1.23

fig. 49

Gas shut-off valve closed (1), gas shut-off valve
open (2)

fig. 50

Removing the cover from the connection box

fig. 51

Installing the cover of the connection box

Checking the control unit; connections to the boiler

If an On/Off thermostat is used and the boiler does not react to
a heat request:
 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Remove the cover from the connection box (see fig. 50).
 Use a jumper wire to create a bridging circuit between the two
"WA" contacts (see fig. 53, pos. 3).
 Connect the heating system to the power supply, insert the
main fuse or switch on the circuit breaker.
 Set the main switch on the BC10 to "1" (On).

 If the boiler switches to heating mode (operating code [-/h/\| )
after some time, the cause of the fault must be outside the
boiler.
 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off). See page 9 „Menu
structure of the BC10 basic controller“.
 Remove the bridge between the two "WA" contacts (see fig. 53,
pos. 3).
 Connect the On/Off thermostat directly to the two "WA"
contacts of the boiler using a short cable (see fig. 53, pos. 3).
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).
 Set the On/Off thermostat to the request position.
 If the boiler switches to heating operation (operating code
[-/h/\| ) after some time, the fault is caused by the cable
between the On/Off thermostat and the boiler.

104

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions

 If the boiler does not switch to heating mode after some time,
the fault is caused by the On/Off thermostat.
 Correct the cause of the fault.
 Fit the cover on the connection box (see fig. 51).
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).
If a modulating control unit is used and the boiler does not
react to a heat request:
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Remove the cover from the connection box (see fig. 52).

fig. 52

Removing the cover from the connection box

 Connect the modulating control directly to the two "RCxx"
contacts of the boiler using a short cable (see fig. 53, pos. 1).
 Connect the heating system to the power supply, insert the
main fuse or switch on the circuit breaker.
 Set the main switch on the BC10 to "1" (On).
 Set the modulating control to the request position.
 If the boiler switches to heating mode (operating code [-/h/\| )
after some time, the fault is caused by the cable between the
modulating control and the boiler.
 If the boiler does not switch to heating mode after some time,
the fault is caused by the modulating control.

 Correct the cause of the fault.
PK

Grid

RC FA WA FW EV

1
fig. 53

External connection board

pos. 1: RC Room thermostat (connection color orange)
pos. 2: Outdoor-temperature sensor (connection color
blue)
pos. 3: Potential-free On/Off thermostat (connection color
green)
pos. 4: DHW temperature sensor (connection color grey)
pos. 5: External switching contact, potential-free for floor
heating safety etc. (connection color red)
pos. 6: DO NOT USE
pos. 7: Primary loop pump 120V 60Hz (connection color
green)
pos. 8: DHW tank pump 120V 60Hz (connection color grey)
pos. 9: DHW recirculating pump 120V 60Hz (connection
color lilac)
pos. 10: Main connection 120V 60Hz (connection color
white)
pos. 11: Fuse holder

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

105

Actions

 Fit the cover on the external connection box (see fig. 54).
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).

8.1.24

fig. 54

Installing the cover of the connection box

fig. 55

Bleeding the gas supply pipe

Bleed the gas supply pipe

 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Close the gas shut-off valve (see fig. 56, pos. 1).
 Open the screw plug on the testing nipple for the inlet gas pressure and for purging (fig. 55) by two turns and install a hose.
 Open slowly the gas shut-off valve.
 Run the gas that flows out through a water bath.
 Close the gas shut-off valve when no more air escapes.
 Remove the hose and tighten the screw plug again.
 Carefully open the gas shut-off valve (see fig. 56, pos. 2).
 Check the testing nipple for leaks.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).

106

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions
8.1.25

Measuring the inlet gas pressure (flow pressure)

 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Open at least one thermostatic radiator valve.
 Close the gas shut-off valve (see fig. 56, pos. 1).
 Open the screw plug on the testing nipple for the inlet gas pressure (see fig. 57, pos. 1) by two turns.
 Set the pressure gauge to zero.
 Connect the measuring hose of the pressure gauge to the
testing nipple (see fig. 57, pos. 2).
 Carefully open the gas shut-off valve (see fig. 56, pos. 2).
fig. 56

Gas shut-off valve closed (1), gas shut-off valve
open (2)

fig. 57

Measure the inlet gas pressure

 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).
 Put the heating boiler into operation, see "Flue gas test" menu
on page 10.
 Measure the inlet gas pressure when the "Burner" (On/Off) LED
on the BC10 basic controller lights.
 The inlet gas pressure must be:
– for natural gas – min. 3.5 to 10.5 inch W.C (8.7 to 26.1
mbar), nominal supply pressure 7.0 inch W.C. (17,4 mbar)
– for LPG – min. 8.0 to 13.0 inch W.C. (19.9 to 32.3 mbar),
nominal supply pressure 11.0 inch W.C. (27.4 mbar).
 Set the main switch on the BC10 to "0" (Off).
 Close the gas shut-off valve (see fig. 56, pos.1).
 Remove the hose and tighten the screw plug on the testing
nipple again.
 Open again the gas shut-off valve (see fig. 56, pos. 2).
 Check the testing nipple for leaks.
 Fit the casing.
 Set the main switch on the BC10 to "1" (On).
NOTE!
If the required inlet gas pressure is not available,
you should consult your gas utility company. If the
inlet gas pressure is too high, a gas pressure regulator is to be integrated upstream of the gas valve.

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

107

8
8.1.26

Actions
Measure and adjust the gas/air ratio

 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Close the gas shut-off valve (see fig. 56, pos. 1).
 Open at least one thermostatic radiator valve.
 Open the screw plug on the testing nipple for the burner pressure (fig. 58, pos. 1) by two turns.
 Set the pressure gauge to zero.
 Use a hose to connect the + connection of the pressure gauge
to the burner pressure measuring nipple (fig. 58, pos. 2).
 Open the gas shut-off valve (see fig. 56, pos. 2).
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).

fig. 58
 Put the heating boiler into operation, see "Service Mode" menu
on page 11.

Checking the gas/air ratio

incorrect

correct

incorrect

-0.02

0
0.02
(inch W.C.)

 Read out the gas/air ratio from the pressure gauge when the
boiler is in part-load operation.
The boiler is running in part-load operation when, in the
"Service mode" menu L 3 0 has been set.
 The differential pressure (pGas - pAir) must be
-0.02 inch W.C. (-5 Pa) (+/-0.02 inch W.C. = +/-5 Pa)
(read-out on pressure gauge: -0.04 – 0 inch W.C. =
-10 Pa – 0 Pa). See fig. 59.

-0.06

-0.04

turn counterclockwise

turn clockwise

fig. 59

Differential pressure gas/air ratio part-load

fig. 60

Adjusting the gas/air ratio

 If the gas/air ratio is incorrect, it can be adjusted on the set
screw (fig. 60, pos. 1).
NOTE!
The set screw is located behind the screw-on
cover. This must be removed first.
 Set the main switch on the BC10 to "0" (Off).
 Close the gas shut-off valve (see fig. 56, pos. 1).
 Remove the hose and tighten the screw plug on the testing
nipple again.
 Open the gas shut-off valve (see fig. 56, pos. 2).
 Check the testing nipple for leaks.
 Fit the casing.
 Set the main switch on the BC10 to "1" (On).

108

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions
8.1.27

Measuring the carbon monoxide content (CO)

 Measure the carbon monoxide content on the flue gas sampling
point (see fig. 61).
 The CO values in an air-free condition must be below 400 ppm
or 0.04 vol. %.
 Values of 400 ppm and up indicate that the burner adjustment
may be wrong, the gas burner fitting or the heat exchanger are
dirty or that there may be burner faults.
 You must establish and resolve the cause. The boiler must be
operational when you do this.

8.1.28

fig. 61

Flue gas sampling point

fig. 62

Removing the cover from the connection box

Transformer; replacing

 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Dismantle the cover of the external connection board
(see fig. 62).

 Pull the 4 plugs from the external connection board
(see fig. 63, pos. 1, 2, 3 and 4).

1
4

fig. 63

Pulling the external connection board plug

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

109

Actions

 Loosen the 2 external connection board fastening screws (see
fig. 64, pos. 1).

fig. 64

Loosening the fastening screws

fig. 65

Removing the external connection board

fig. 66

Removing the transformer shield

 Remove the external connection board (see fig. 65).

 Remove the transformer shield (see fig. 66).

110

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions

 Pull both plugs on the rear of the transformer (see fig. 67).
 Check to see if you measure any resistance on the two cable
plugs. If you do then the transformer is not the problem. If you
don't measure any resistance then replace the transformer as
described in the following steps.

fig. 67

Pulling the plugs from the transformer

fig. 68

Removing the transformer

fig. 69

Draining the Logamax plus GB142

 Remove the transformer by pulling it in the direction indicated
by the arrow (see fig. 68).
 Install the new transformer.
 Re-assemble all parts and plugs in reverse order of disassembly.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).

8.1.29

Automatic air purging system; replacing

 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Close the maintenance shut-off valves and drain the Logamax
plus GB142. (see fig. 69).

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

111

Actions

 Remove the plastic cover from the top of the boiler (see fig. 70).

fig. 70

Removing the plastic cover of the automatic air
purging system

fig. 71

Removing the float cap

fig. 72

Dismantling the valve case for the automatic air
purging system

 Remove the float cap (see fig. 71).

 Dismantle the valve case by pulling it upwards through the
opening in the housing (see fig. 72).
 Assemble the new valve case and all other parts in reverse
order of disassembly.
NOTICE
Fill and purge the Logamax plus GB142 as
required.
See installation and maintenance instructions
Logamax plus GB142-24/30/45/60.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).

112

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions
8.1.30

Burner; replacing

 Switch off the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Close the gas shut-off valve (see fig. 73, pos. 1).

fig. 73

Gas shut-off valve closed (1), gas shut-off valve
open (2)

 Remove the cable plug from the gas control valve
(see fig. 74, pos. 1).

1
fig. 74

Replacing the gas control valve
(e.g. HONEYWELL gas control valve)

 Remove both cable plugs from the fan unit (see fig. 75, pos. 1).

1
fig. 75

Disconnecting the cable plug from the fan unit

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

113

Actions

 Loosen the union nut of the gas control valve (see fig. 76,
pos. 1).

1
fig. 76

Loosening the gas control valve

 Loosen both sets of retaining clips (fig. 76, pos. 2 and fig. 77,
pos. 1) of the burner cover and remove the burner cover with
the fan unit and the gas burner fitting.

1
fig. 77

Loosening the retaining clips

 Remove the burner gasket (see fig. 78, pos. 1).
 Remove the gas/air distributor plate (see fig. 78, pos. 2).
 Remove the orifice plate (only applies to Logamax plus
GB142-24/30 and GB142-60) (see fig. 78, pos. 3). Note that
the orifice plate of the GB142-60 has a different shape.

 Remove the burner (see fig. 78, pos. 4).

2
3
4

fig. 78

114

Removing the burner

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions

 Install the new burner (see fig. 79).
WARNING!
Fit the burner so that the scale mark is located on
the left-hand side (see fig. 79).
 Re-assemble all other parts in reverse order of disassembly.

fig. 79

Installing the burner

fig. 80

Gas shut-off valve closed (1), gas shut-off valve
open (2)

 Open the gas shut-off valve (see fig. 80, pos. 2).
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).
 Also check all joints and gaskets affected by the replacement
activities while carrying out the tightness test in operating
conditions.
 Set the gas/air ratio again. See paragraph 8.1.26.

8.1.31

Sight glass; replacing

 Switch off the power supply of the heating system on the circuit
breaker.

 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Loosen both screws of the sight glass (see fig. 81, pos. 1).
 Remove the sight glass mounting plate.
 Disassemble the sight glass inclusive of both gaskets.
 Assemble the new sight glass and all further parts in reverse
order of disassembly; remember to fit new gaskets.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).

fig. 81

Loosening the screws of the sight glass

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

115

8
8.1.32

Actions
Condensate trap; replacing

 Switch off the power supply of the heating system on the circuit
breaker.

 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Pull the condensate trap from the condensate plate
(see fig. 82, pos. 1).
 Pull the internal condens bypass pipe from the condensate trap
(see fig. 82, pos. 2).
 Loosen the condensate trap from the connection (see fig. 82,
pos. 3) and remove it.
 Fill the new condensate trap with water.
 Re-assemble the new condensate trap in reverse order of
disassembly.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).
8.1.33

3
fig. 82

Disconnecting the condensate trap connection

fig. 83

Draining the Logamax plus GB142

fig. 84

Loosening the pressure sensor

Pressure sensor; replacing

 Loosen the pressure sensor by removing the securing clip (see
fig. 84).
 Assemble the new pressure sensor and the plug in reverse
order of disassembly.
NOTICE
Fill and purge the Logamax plus GB142 as
required.
See installation and maintenance instructions
Logamax plus GB142-24/30/45/60.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).

116

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions
8.1.34

Heat exchanger; replacing

 Switch off the power supply of the heating system on the circuit
breaker.
 Close the maintenance shut-off valves and drain the Logamax
plus GB142, see 116, fig. 83.
 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Close the gas shut-off valve(see fig. 85, pos. 1).

fig. 85

Gas shut-off valve closed (1), gas shut-off valve
open (2)

 Remove the cable plug from the gas control valve
(see fig. 86, pos. 1).

fig. 86

Replacing the gas control valve
(e.g. HONEYWELL gas control valve)

 Remove both cable plugs from the fan unit (see fig. 87, pos. 1).

1
fig. 87

Disconnecting the cable plug from the fan unit

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

117

Actions

 Loosen the union nut of the gas control valve (see fig. 88,
pos. 1).

1
fig. 88

Loosening the gas control valve

 Pull both retaining clips (see fig. 89, pos. 1) on the burner cover
to open them and remove the burner cover with the fan unit and
the gas control valve.

1
fig. 89

Loosening the retaining clips

 Remove the burner gasket (see fig. 90, pos. 1).
 Remove the gas/air distributor plate (see fig. 90, pos. 2).
 Remove the orifice plate (only applies to Logamax plus
GB142-24/30 and GB142-60) (see fig. 90, pos. 3). Note that
the orifice plate of the GB142-60 has a different shape.

 Remove the burner (see fig. 90, pos. 4).

2
3
4

fig. 90

118

Removing the burner

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions

 Disconnect the plug and socket connections of the supply,
return and safety sensors (see fig. 91, 92 and 93).

fig. 91

Loosening the plug and socket connections of the
supply sensor

fig. 92

Disconnect the plug and socket connection of the
return sensor

fig. 93

Disconnect the plug and socket connection of the
safety sensor

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

119

Actions

 Disassemble the supply and return sensors (see fig. 94, pos. 1
and 2).

WARNING
To prevent mix-ups, the supply sensor is marked
by a red sleeve on the side of the cable harness.

fig. 94

Replacing the supply/return sensors

 Dismantle the safety sensor (see fig. 95, pos. 1).

fig. 95

Dismantling the safety sensor

fig. 96

Replacing the hot surface ignitor

 Disconnect the hot surface ignitor and ionization electrode
plugs.
 Loosen the fastening screws (see fig. 96, pos. 1).
 Pull the earth cable from the hot surface ignitor (see fig. 96,
pos. 2).
 Dismantle the mounting plate (see fig. 96, pos. 3).

120

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions
 Remove both the hot surface ignitor and the ionization electrode by pulling them loose (see fig. 97, pos. 1).

fig. 97

Removing the hot surface ignitor and the ionization
electrode

 Dismantle the condensate trap connection to the condensate
collector (see fig. 98, pos. 1).

fig. 98
 Open the four latches of the condensate collector
(see fig. 99, pos. 1).

Dismantling the condensate trap connection to the
condensate collector

fig. 99

Opening the latches of the condensate collector

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

121

Actions

 Remove the condensate collector (see fig. 100, pos. 1).

fig. 100 Removing the condensate collector
 Loosening the backflow connection between the primary pump
and heat exchanger (see fig. 101, pos. 1).
 Dismantle the tension spring between the supply pipe and the
heat exchanger (see fig. 101, pos. 2).

1
2

fig. 101 Loosening the backflow connection and dismantling
the tension spring
 Loosening with one turn the nut between the supply connection
and three way valve connection AB
(see fig. 102, pos. 2).
 Pull the supply pipe out of the heat exchanger (see fig. 102,
pos. 1).

WARNING!
Water will be released.

fig. 102 Removing the supply pipe

122

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions
 Loosen the fastening screws of the combustion air supply and
flue gas exhaust connections (see fig. 103, pos. 1).

fig. 103 Loosening the fastening screws of the combustion air
supply and flue gas exhaust connections
 Pull the combustion air supply (see fig. 104, pos. 2) and flue
gas exhaust (see fig. 104, pos. 1) connections on top of the
boiler upwards to remove them.

fig. 104 Loosening the combustion air supply and flue gas
exhaust connections
 Loosen the 6 fastening screws of the flue gas adapter
(see fig. 105, pos. 1).

fig. 105 Loosening the fastening screws

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

123

Actions

 Remove the flue gas adapter (see fig. 105, pos. 1) from the top
of the boiler.

fig. 106 Removing the flue gas adapter
 Remove the heat exchanger by grabbing its bottom end and
pulling forward and then pushing it upwards (see fig. 107,
pos. 1).
 Assemble the new heat exchanger and all other parts in reverse
order of disassembly.

NOTICE!
Fill and purge the Logamax plus GB142 as
required. See installation and maintenance instructions Logamax plus GB142-24/30/45/60.
Remove the flue gas collector from the old heat
exchanger, including the oval seal. Put silicon kit
on both sides of the oval seal, the flue gas collector
and the heat exchanger. Reassemble the flue gas
collector with the oval seal to the heat exchanger.
Check if the oval seal is placed correctly by
opening the condensate collector (see page 122,
fig. 100).

fig. 107 Dismantling the heat exchanger

 Open the gas shut-off valve (see fig. 108, pos. 2).
 Switch on the power supply of the heating system on the circuit
breaker.
 Set the main switch on the BC10 to "1" (On).
 Also check all joints and gaskets affected by the replacement
activities while carrying out the tightness test in operating
conditions.
 Set the gas/air ratio again. See paragraph 8.1.26, page 108.

fig. 108 Gas shut-off valve closed (1), gas shut-off valve open
(2)

124

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Actions
8.1.35

UBA 3; replacing

 Switch off the power supply of the heating system on the circuit
breaker.

 Set the main switch on the BC10 to "0" (Off).
 Remove the casing.
 Loosen the fastening screw of the UBA 3 (see fig. 109, pos. 1).
 Pull the UBA 3 forward in the direction indicated by the arrow
(see fig. 109, pos. 2).
 Install the new UBA 3.
 Tighten the fastening screw again.
 Fit the casing.
 Switch on the power supply of the heating system on the circuit
breaker.

 Set the main switch on the BC10 to "1" (On).
fig. 109 Dismantling the UBA 3

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

125

126

L
PE
N

10
11
9

PE
N
L

14
12
13

120 VAC

120 VAC
Hot
surface
ignitor

grey
2
FW
1

green
2
1
WA
2

blue
FA
1
2

1
2

External 3-way valve
External switch contact
Potential-free e.g.
for floor heating
DHW sensor
On/Off temperature
control, potential-free
Outdoor-temperature
sensor
Modulating room controller

Boiler circulator
120 VAC, max. 250 VA

DHW circulator
120 VAC, max. 250 VA

External connection for specialist servicing company
8
7
4
3
2

6
5
4
3
2
1

24 VRAC

Bus
Function module

BC10 connector

orange

Supply sensor

Safety-temperature sensor

Return sensor

230 VAC
230 VAC
10 VAC
10 VAC
24 VAC
0 VAC
24 VRAC

58
57

35
8
43
34

red

33
60

17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1

2
DWV

54
51
46
19
23
79
53
77
26
63
64
75
74
36
37
58
57

white

Pressure
sensor

81-pole connector

Pin 81

green

Ionization

81-pole connector
(AC 0, 10, 24 and 120 V)

Earth

55
28
Pin 1

N PE

61
PK

Transformer

N PE

24
PS

Gas burner
fitting

grey

KIM

Fan unit

N PE

13
PZ

lilac

N 120 L
VAC

Pin 1

N PE

120 VAC
120 VAC

Circulating pump
120 VAC, max. 250 VA

Mains supply
120 VAC 60 Hz

Operating switch

white

Pin 16

N
Grid

5
4
3
2
1

4
3
2
1

1
2
3
4

Earth
120 VAC
Function module

15
16
13

120 VAC
Function module

3
2
1

High Voltage

N
3
7
4

6
5

L
L

16-pole connector

Connection box UBA 3.0

8
16
15
1

N PE L

16-pole connector
(120 VAC)

9
Appendix

Appendix
WARNING

Label all wires prior to disconnection when servicing.
Wiring errors can cause improper and dangerous operation.

RC
1
1

70
61
62

1
28
90
81
25
52
27

23
79
53

76
49

16
44

17
45

69
68
67

fig. 110 Electric circuit diagram

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Appendix

Gas orifice diameter Altitude 0 - 10,200 ft
Boiler capacity

24 kW

30 kW

45 kW

60 kW
table 5

Type of gas supply

Venturi article
number

Altitude 4,001 - 10,200 ft
with CO2 correction

[inch]

[mm]

[inch]

[mm]

Natural gas H

423.072A

0.175

4.45

0.179

4.55

LPG P

423.072A

0.132

3.35

0.134

3.40

Natural gas H

423.072A

0.175

4.45

0.177

4.50

LPG P

423.072A

0.132

3.35

0.134

3.40

Natural gas H

423.170A

0.213

5.40

0.219

5.55

LPG P

423.170A

0.163

4.15

0.163

4.15

Natural gas H

423.173A

0.295

7.50

0.301

7.65

LPG P

423.173A

0.213

5.40

0.215

5.45

Gas orifice diameter

Type of gas
supply

Factory setting of gas burner fitting

Natural gas H

Delivered factory-set to Wobbe index
14.1 kWh/m3 (based on 59 °F (=15°C),
14.7 psi (=1,013 mbar)), suitable for
Wobbe index range 11.3 – 15.2 kWh/m3.
Information on gas type instruction plate:
Set to gas category: G 20 – 2E.
Previous indications: set to Wobbe index
15.0 kWh/m3 (based on 32 °F (=0°C), 14.7 psi
(=1,013 mbar)), suitable for
Wobbe index range 12.0 – 15.7 kWh/m3.

LPG P

Suitable for propane after conversion (also see
the chapter "Conversion to another type of gas
supply").
Information on gas type instruction plate:
Set to gas category: G 31 – 3P.

Table 6

No CO2 correction

Factory setting of gas burner fitting

 The diameter of the gas orifice islocated on the gas orifice.

 The article number of the Venturi is located on both clamps of
the Venturi (see fig. 111, pos. 1 and 2).

2
fig. 111 Venturi article number

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

127

Spare parts

Below is a list of the spare parts for this boiler. Look up the position number in the exploded view drawing on the next two pages for the
illustration. Spare parts may be ordered from Buderus.
Pos.
1
2
3
4
5
6
7
9
10
11
12
13
14
15

16
17
18
19
20
21
22
23

24
25
26
27
28
29
30
31
32
33

Description
Casing 24/30 kW
Casing 45/60 kW
Casing latches left (2 pc)
Casing latches right (2 pc)
Casing seal 24/30 kW
Casing seal 45/60 kW
Wall mounting bracket
Back panel 24/30 kW
Back panel 45/60 kW
Cap air vent
Seal ring Ø 3”
Seal ring Ø 80 mm
Flue gas collector
Oval seal
Heat exchanger 24/30 kW
Heat exchanger 45 kW
Heat exchanger 60 kW
Heat exchanger baffle 24/30 kW
Seal condensate collector 24/30 kW
Seal condensate collector 45 kW
Seal condensate collector 60 kW
Condensate collector + sealing 24/30 kW
Condensate collector + sealing 45 kW
Condensate collector + sealing 60 kW
Clamp
Sensor NTC
Revision set air vent **
Sight glass
Burner box 24/30 kW
Burner box 45 kW
Burner box 60 kW
Safety sensor
Seal burner 24/30 kW
Seal burner 45 kW
Seal burner 60 kW
Gas/air distribution plate 24/30 kW
Gas/air distribution plate 45 kW
Gas/air distribution plate 60 kW
Orifice plate 24/30 kW
Orifice plate 60 kW
Burner 24/30 kW
Burner 45 kW
Burner 60 kW
Gas-air inlet
Seal fan
Ionization electrode
Hot surface ignitor
Shield hot surface ignitor
Mounting plate
Seal mounting plate (5 pc)

Product No.
7099988
7099901
7099039
7099038
7098752
7098798
7098364
7099001
7099903
7100250
77470s
7096475
7098857
7098858
7746900159
7746900160
7746900161
7098828
7098834
7098838
67900522
7098840
7098844
67900521
7098848
7100136
7098822
7098575
7099057
7098875
67900525
78194
7098916
7098920
67900526
7100922
7098926
67900527
7100920
7746900120
7099003
7098932
67900528
7099004
7099023
78195
7099006
7100229
7098852
7098850

Pos.
34
35
36
37
38
39
40
41
42

44
45
47
48
49
50
51
52
53
54
55
56
57

Description
Air inlet pipe; 24/30 kW
Air inlet pipe; 45/60 kW
Seal Ø50 mm (5 pc)
Venturi 24/30 kW
Venturi 45 kW
Venturi 60 kW
Seal set (4 pc)
Fan
Gas control valve
Gas supply pipe GB142 USA
Spring (5 pc)
Seal 2x16x22 (5 pc)
L.P. Orifice Ø 3.35 - 24/30 kW
0-10,200 ft
L.P. Orifice Ø 3.40 - 24/30 kW
4,001-10,200 ft
L.P. Orifice Ø 4.15 - 45 kW
0-10,200 ft
N.G. Orifice Ø 4.45 - 24/30 kW
0-10,200 ft
N.G. Orifice Ø 4.50 - 30 kW
4,001-10,200 ft
N.G. Orifice Ø 4.55 - 24 kW
4,001-10,200 ft
N.G. Orifice Ø 5.40 - 45 kW
0-10,200 ft
L.P. Orifice Ø 5.40 - 60 kW
0-10,200 ft
L.P. Orifice Ø 5.45 - 60 kW
4,001-10,200 ft
N.G. Orifice Ø 5.55 - 45 kW
4,001-10,200 ft
N.G. Orifice Ø 7.50 - 60 kW
0-10,200 ft
N.G. Orifice Ø 7.65 - 60 kW
4,001-10,200 ft
Condensate trap, part of pos. 88
Seal condensate trap (5 pc)
Supply pipe CH; 24/30/45 kW
Supply pipe CH; 60 kW
Return pipe 24/30/45 kW
Return pipe 60 kW
Pressure sensor **
Bottom plate
Transformer 120V
Grommet
External connection board
External connection board cover
Fuse 5 AF slow blow
UBA cover
UBA 3 - 120V

Product No.
7099024
7099023
7099058
7099020
7099925
7099931
7099021
78184
7099025
76685
7100549
7098778
76687
7746901353
7746901355
7099016

7746901421
7746901354
76690
76690
7746901357
7746901356
76686
7746901358
8718600689
7100742
75990
75991
709965
709945
8718600019
7099049
78191
7099050
7099042
7099046
73904s
7099047
7099707

** not shown in exploded views

128

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Spare parts
Pos.
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88

Description

Product No.

Drawer
Drawer front
Controller connection plate
On/off switch
Controller cover
Boiler ident. module 24 kW
Boiler ident. module 30 kW
Boiler ident. module 45 kW
Boiler ident. module 60 kW
Cable harness low voltage
Cable harness high voltage
O-ring (10 pc)
Sealing bush (set)
Cable harness of on/off switch
Cable harness BX holder
Fuse holder
Seal Ø60 mm (5 pc)
O-ring set orifice
Seal (5 pc)
Set screw M5x20 (5 pc)
Cap 24/30 kW
Double nipple THR x COMPR
Cabel saddle (10 pc)
Bolt M6x16 (2 pc)
Clip pressure sensor
Drainplug
Cap connection piece
Clip (5 pc)
Centering ring (5 pc)
Coupling nut pump
Seal pump (10 pc)
Coupling nut pump
Conversion set pump
Condensate drain set, incl. pos. 44

7099043
7099037
78186
7099041
73698
78223
78224
78225
78226
78193
7099957
38434s
7099002
7099072
7099070
38345
7098878
7099018
7099059
7099065
79105
75977
7098810
7099078
7101370
7099364
38498
73651s
73480s
73481s
15022s
15020
73149
8718600686

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

129

Spare parts

Exploded view Logamax plus GB142-24/30

10
21

29
17

74
23

24
9

28
74

30
14

20
66

18
17

84
85
35

87
37

85
86

38
40
74

41
42

43
39

6
75

4
76

2
64

54
69
63
62
57

70
55

61
53

60
68

50
59
58

130

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

Spare parts

Exploded view Logamax plus GB142-45/60
71

29
32

12
88

20
66

15
18

5
84

85
87
35

40
41

45
44

74
72

85
86

81
39

67
48

63
57

53
52

69
51

60
68
59
50

Logamax plus GB142-24/30/45/60 - We reserve the right to make any changes due to technical modifications!

131

Unites States and Canada

Products manufactured by
Bosch Thermotechnik GmbH
Sophienstrasse 30-32
D-35576 Wetzlar
www.buderus.com
Bosch Thermotechnology Corp. reserves the right
to make changes without notice due to continuing
engineering and technological advances.

721.494A 0007

Bosch Thermotechnology Corp.
50 Wentworth Avenue
Londonderry, NH 03053
Tel. 603-552-1100
Fax 603-584-1681
www.buderus.us
U.S.A.

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Service Manual Logamax Plus GB142 (USA/CA) En 72149400 07 Instructions 12.2011 US

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