Pentair Minimax Nt Standard Series Users Manual 472032_revA.p65

NT Standard Series to the manual 7f5f9daa-fc69-3874-d9c3-4aa5e69a5a4e

2015-02-06

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MiniMax NT Standard Series
POOL & SPA HEATERS
OPERATION & INSTALLATION MANUAL
WARNING
FOR YOUR SAFETY - READ BEFORE OPERATING
Warning: If you do not follow these instructions exactly, a fire or explosion may
result, causing property damage, personal injury or loss of life.
For additional free copies of this manual; call (800) 831-7133.

To
Consumer
Retain For
Future
Reference

U.S. Patent Numbers
6,295,980
5,318,007 - 5,228,618
5,201,307 - 4,595,825

WARNING
Warning: Improper installation, adjustment, alteration, service or maintenance can
cause property damage, personal injury or death. Installation and service must be
performed by a qualified installer, service agency or the gas supplier.

WHAT TO DO IF YOU SMELL GAS

For Your
Safety

•
•
•
•

Do not try to light any appliance.
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.

Do not store or use gasoline or other flammable vapors and
liquids in the vicinity of this or other appliances.
Pentair Pool Products, Inc.
1620 Hawkins Ave., Sanford, NC 27330 • (919) 774-4151
10951 W. Los Angeles Ave., Moorpark, CA 93021 • (805) 523-2400
Rev. A 1-2-02

P/N 472032

Table of Contents
Introduction ...............................................................................................................

Important Notices ......................................................................................................................................................................

Code Requirements ...................................................................................................................................................................

Warranty Information .................................................................................................................................................................

Operation ....................................................................................................................

Safety Rules ..............................................................................................................................................................................

HSI (Hot-Surface Ignition) Lighting/Operation ...........................................................................................................................

Installation Instructions ............................................................................................

Specifications ............................................................................................................................................................................

Installation — Electrical .............................................................................................................................................................

Installation — Remotes (2 and 3 Wire) ...................................................................................................................................... 8 - 9
Installation — Wiring Diagram ...................................................................................................................................................

Installation — Water Connections ..............................................................................................................................................

Installation — Plumbing .............................................................................................................................................................

Installation — Gas Line ............................................................................................................................................................. 12
Pipe Sizing Chart/Gas Pressure Requirements ......................................................................................................................... 12
Regulated Manifold Pressure Test .............................................................................................................................................

Venting — Indoor Installations ................................................................................................................................................... 13 - 16
Venting — Outdoor Installations ................................................................................................................................................ 17
Basic Operation — General Description .................................................................................................................................... 18
Basic Operation — Safety Controls ........................................................................................................................................... 19 - 20
Basic Operation — HSI Ignition Module .................................................................................................................................... 20
Thermostat (Programming & Layout) ........................................................................................................................................ 21
Temperature & Time Setting (Programming) ............................................................................................................................. 22 - 23

Maintenance ............................................................................................................................ 24
Maintenance Instructions ........................................................................................................................................................... 24
Pressure Relief Valve ................................................................................................................................................................ 24
Maintenance (Water Treatment) ................................................................................................................................................ 25

Trouble Shooting ....................................................................................................... 26
Normal Operation Sequence ..................................................................................................................................................... 26 - 27
Troubleshooting & Service ......................................................................................................................................................... 27 - 28
Troubleshooting (General) .........................................................................................................................................................

MiniMax NT Standard Parts List & Exploded View (Dual Voltage) ............................................ 30-31
Warranty Information .................................................................................................
P/N 472032

Back Cover

Rev. A 1-2-02

Introduction

MiniMax NT Standard
Pool and Spa Heaters
Congratulations on your purchase of a MiniMax NT Standard high performance heating system. Proper
installation and service of your new heating system and correct chemical maintenance of the water will
ensure years of enjoyment. The MiniMax NT Standard is a compact, lightweight, efficient, induced-draft,
gas fired high performance pool and spa heater that can be directly connected to schedule 40 PVC pipe. The
MiniMax NT Standard also comes equipped with the Pentair multifunction 7800 temperature controller
which shows, at a glance, the proper functioning of the heater. All HSI (hot-surface ignition) MiniMax NT
Standard heaters are designed with a direct ignition device (HSI) which eliminates the need for a standing
pilot. The MiniMax NT Standard requires an external power source (120/240 VAC 50/60 Hz) to operate.

IMPORTANT NOTICES
...For the installer and operator of the MiniMax NT Standard pool and spa heater. The manufacturer’s
warranty may be void if, for any reason, the heater is improperly installed and/or operated. Be sure to follow
the instructions set forth in this manual. If you need any more information, or if you have any questions
regarding to this pool heater, please contact Pentair Pool Products, Inc. at (800) 831-7133.
These heaters are designed for the heating of swimming pools and spas, and should never be employed for
use as space heating boilers, general purpose water heaters, in non-stationary installations, or for the heating
of salt water.
Do not use the heater to protect pools or spas from freezing if the final maintenance temperature desired is
below 60° F. as this will cause condensation related problems.

CODE REQUIREMENTS
The installation must conform with local codes or in the absence of local codes with the latest National Fuel
Gas Code, ANSI Z223.1, and the latest edition of the National Electrical Code, NFPA 70.
Installation in Canada to be made in accordance with the latest CAN/CGA-B149.1 or .2 and CSA C22.1
Canadian Electric Code, part 1.

Rev. A 1-2-02

P/N 472032

Operation

This instruction manual provides operating
instructions, installation and service information
for the MiniMax NT Standard high performance
heater. The information in this manual applies to
the MiniMax NT Standard 200, 250, 300, and
400 models.
It is very important that the owner/installer read
and understand the section covering installation
instructions, and recognize the local and state codes
before installing the MiniMax NT Standard. History
and experience has shown that most heater damage
is caused by improper installation practices.

WARRANTY INFORMATION
The MiniMax NT Standard pool heater is sold with
a limited factory warranty. Specific details are
described on the back cover of this manual and a
copy of the warranty and warranty registration
card are included with the product. Return the
warranty registration card after filling in the serial
number from the rating plate inside the heater.
Pentair Pool Products’ high standards of excellence
include a policy of continuous product improvement
resulting in your state-of-the-art heater. We reserve
the right to make improvements which change the
specifications of the heater without incurring an
obligation to update the current heater equipment.

Operation

SAFETY RULES
1. Spa or hot tub water temperatures should never
exceed 104° F. A temperature of 100° F. is
considered safe for a healthy adult. Special
caution is suggested for young children.
2. Drinking of alcoholic beverages before or during
spa or hot tub use can cause drowsiness which
could lead to unconsciousness and subsequently
result in drowning.
3. Pregnant women beware! Soaking in water
above 100° F. can cause fetal damage during the
first three months of pregnancy (resulting in the
birth of a brain-damaged or deformed child).
Pregnant women should stick to the 100° F.
maximum rule.

4. Before entering the spa or hot tub, the user
should check the water temperature with an
accurate thermometer. Spa or hot tub
thermostats may err in regulating water
temperatures by as much as 4° F.
5. Persons with a medical history of heart disease,
circulatory problems, diabetes or blood pressure
problems should obtain their physician's advice
before using spas or hot tubs.
6. Persons taking medication which induce
drowsiness, such as tranquilizers, antihistamines
or anticoagulants should not use spas or hot
tubs.

WARNING
Should overheating occur or the gas supply fail to shut off, turn off the manual gas control valve to the
appliance. Do not use this heater if any part has been under water. Immediately call a qualified service
technician to inspect the heater and to replace any part of control system and gas control which has been
under water.
P/N 472032

Rev. A 1-2-02

Operation (Lighting)

MINIMAX NT STANDARD HSI ELECTRONIC IGNITION LIGHTING/OPERATION
FOR YOUR SAFETY: READ BEFORE LIGHTING

WARNING
If you do not follow these instructions exactly, a fire or explosion may result causing personal injury, loss of life
and property damage.
Do not attempt to light the heater if you suspect a natural gas leak. Lighting the heater can result in a fire or
explosion which can cause personal injury, death, and property damage.
A. This heater is equipped with an ignition device
which automatically lights the main burners.
Do not try to light the burners by hand.
B. BEFORE OPERATING, smell all around
the heater area for gas. Be sure to smell next
to the floor because some gas is heavier than
air and will settle on the floor.
WHAT TO DO IF YOU SMELL GAS
- Do not try to light any heater.
- 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.

C. Use only your hand to push in or turn the gas
control knob. Never use tools. If the knob will
not push in or turn by hand, don't try to repair it.
Call a qualified service technician. Forced or
attempted repair may result in a fire or explosion.
D. Do not use this heater if any part has been under
water. Immediately call a qualified service
technician to inspect the heater and to replace
any part of the control system and any gas
control which has been under water.
E. The MiniMax NT Standard incorporates the
Pentair 7800 temperature controller to aid you
in the operation of the heater, and to assist in
diagnosing a failure in the heater’s function.

OPERATING INSTRUCTIONS
1.
2.
3.
4.

5.
6.
7.

STOP! Read the safety information above.
Set the thermostat to the lowest setting.
Turn off electric power to the heater.
This heater is equipped with an ignition device
which automatically lights main burners. Do
not try to light the burners by hand.
Remove the control access door.
Push in gas control knob slightly and turn clockwise
to “OFF”. (If not on “OFF” position.)
Wait five (5) minutes to clear out any gas. If you
then smell gas, STOP! Follow "B" in the safety
information above. If you don't smell gas, go to the
next step.
Turn knob on gas control counterclockwise
to “ON”; see Figure 1.

9.
10.
11.
12.

Replace the control access door.
Turn on the electrical power to the heater.
Set the thermostat to the desired setting.
If the heater will not operate, follow the instructions "To Turn Off Gas To Heater" and call your
service technician or gas supplier.

Gas
Inlet
ON

OFF

Figure 1.

Gas control knob shown in “ON” position.

TO TURN OFF GAS TO APPLIANCE
1. Set the thermostat to lowest setting.
2. Turn off all electric power to the heater if
service is to be performed.
3. Remove control access door.
Rev. A 1-2-02

4. Push in gas control knob slightly and turn
clockwise
to "OFF". Do not force.
5. Replace control access door.
P/N 472032

Installation Instructions
SPECIFICATIONS
IMPORTANT NOTICE: These installation instructions are designed for use by qualified personnel
only, trained especially for installation of this type of heating equipment and related components. Some
states require installation and repair by licensed personnel. If this applies in your state, be sure your
contractor bears the appropriate license.
OUTDOOR VENTILATION
15.50

7.35
2 in. SOCKET

24.05

30.63

LEG

3.50

14.50

Figure 2.

LEG

"A" DIM.
21.63

250

24.63

300

27.63

400

34.13

4.875

8.84

6.64

MODEL
200

DIMENSIONS IN INCHES

"A" DIM.

INDOOR VENTILATION
15.50

INDOOR VENT ADAPTOR
7.35

4 in. Kit
P/N 460506

P/N 460506

4 in. Kit

P/N 460507

5 in. Kit

2.00

24.05

Ø4.88
Ø5.88

5 in. Kit
P/N 460507

30.63

LEG

3.50

14.50

Figure 3.

LEG

8.84

6.64

4.875

MODEL
200

"A" DIM.
21.63

250

24.63

300

27.63

400

34.13

DIMENSIONS IN INCHES

"A" DIM.

P/N 472032

Rev. A 1-2-02

Installation (Electrical)

ELECTRICAL, for MiniMax NT Standard Heaters
Electrical Rating

50/60 Hz

120 / 240 Volts AC, single phase
NOTE

The MiniMax NT Standard heater is prewired for 240 volt AC connection using the “BROWN” female connector and the
“WHITE” common male connector; see below, Figure 4. If you require the heater to be connected to 120 volts AC, remove
the “BROWN” female connector from the “WHITE” common connector; now locate the “BLUE” female connector and plug it
into the “WHITE” common connector.
When connecting the home wiring to the “Line Terminal Block” inside the junction box, follow the polarity as shown below.
Connecting to 120 VAC, make sure that you connect the positive wire to the positive terminal (L), the neutral wire is
connected to the neutral terminal (N) and the ground is connected to the ground terminal (GND); see below, Figure 5.

NOTE
If any of the original wiring supplied with this heater must be replaced, installer must supply
(No. 18 AWG 105° C. U.L. approved AWM low energy stranded) copper wire or it’s equivalent.

In Canada: wires must be CSA approved.

WARNING
The heater must be electrically grounded and bonded in accordance with local codes or in the absence
of local codes, with the latest national electrical codes ANSI/NFPA No. 70.
In Canada: CSA standard C22.1 Canada Electrical Code Part 1 and/or local codes.
Always use crimp type connectors when connecting two wires.

BROWN
FM CONNECTOR
FOR USE WITH
240 VOLT AC

WHITE
COMMON MALE
CONNECTOR

BLUE

TERMINAL BLOCK
FOR AC INPUT
120 / 240 VOLT SINGLE
PHASE "See Below"

FM CONNECTOR
FOR USE WITH
120 VOLT AC

Figure 4.

LINE TERMINAL BLOCK
GROUND
CONNECTION

GREEN WIRE

NEUTRAL / WHITE 120 VAC
LINE #1 FOR 240 VOLT AC

WHITE WIRE

INTERNAL
FACTORY WIRES

N
BLACK WIRE

POSITIVE LINE FOR 120 VOLTS AC
LINE #2 FOR 240 VOLT AC

L
Figure 5.
Rev. A 1-2-02

P/N 472032

Installation (Remotes)

TWO-WIRE OR THREE-WIRE REMOTE HOOK-UP
Before connecting the remote control system please read the following:
1. First turn the gas valve to the "OFF" position and power up the
heater, now using the front buttons on the temperature controller,
set the "SPA" and "POOL" temperature to the maximum setting,
see Page 22.
2. Now turn the heater to the "OFF" mode by using the "OFF" button
on the temperature controller, see Page 22 or by using the main
power switch located on the bottom of the junction box.
3. With the heater in the "OFF" mode, locate the three tabs on the back
of the temperature controller as viewed from the backside,
see Figure 6.
4. • Two-wire remote with temperature control:

1
POOL

SPA

GND

Figure 6.

a) Using 3/16" female quick disconnect connectors, connect one
wire to the "GND" tab of the temperature controller, then the
second wire to either the "SPA" or "POOL" tab.
b) Now return power to the heater but leaving the temperature controller in the "OFF" position,
see Page 22. (Note: If you used the main power switch to turn off the heater, now turn the main power
switch on.) At this time the remote system has control over the heater, and will turn it on and off when
called for by the remote system thermostat thus keep the pool and spa at the desired temperature.

2 WIRE REMOTE

5 A FUSE
FOR AUX2 (PILOT DUTY ONLY)

AUX2
5A
25O V
RELAY

5 3 1

6 4 2

10 A
25O V
RELAY
REMOTE BLOWER
(AUX1)

1 2 3
F
3
2
1

IGN MODULE
1

G VALVE
1

LIMITS
1

POWER
5

TPROBE

}

NOT USED

POOL
SPA
GND

AIR PRESS

24 VAC

PRESS

H LIMIT

T FUSE

PV/MV
MV

PV/MV
MV
PV

A.C LOAD (PUMP/AUX2)
(PILOT DUTY ONLY)

1 2

24 VAC

4
3

BLOWER (POWER) LINE
BLOWER (POWER) LINE

GND

SPA

TEMPERATURE
DISPLAY MODE

10 A
25O V
RELAY
PUMP/AUX2

PUMP
PURGE MODE

REMOTE SWITCH CONTROLLER

Figure 7.

Three-Wire continued on next page.
P/N 472032

Rev. A 1-2-02

Installation (Remotes)

TWO-WIRE OR THREE-WIRE REMOTE HOOK-UP, (cont’d.)
• Three-wire remote:
a) Using 3/16" female quick disconnect connectors, connect the common wire to the "GND" tab of the
temperature controller, then connect the two remaining wires to the temperature controller
corresponding to the remote control device, pool wire to "POOL" tab, spa wire to "SPA" tab.
b) Now return power to the heater. (Note: If you used the main power switch to turn off the heater, now
turn the main power switch on.) At this time, the remote system has control over the heater and if pool
or spa temperature is below the temperature controller setting, then the heater will try to come on.
c) If you desire to reset the temperature settings of the temperature controller, the remote has to be in the
desired mode for you to change the particular setting. Example: You wish to raise or lower the pool
temperature from the factory setting, you must have the remote system in the pool mode, if you wish to
change the spa temperature, you must have the remote system in the spa mode.
5. Now turn on the gas valve to "OPEN" position, the heater is now ready to
operate.
NOTE
The heater factory settings are 78° F. for the pool and 104° F. for the spa.
When connecting a remote control to the MiniMax, you must install the low
voltage thermostat wires in separate conduit from ANY line voltage wires.
Failure to follow these instructions will cause the thermostat relay to react
erratically. A Remote hook-up deactivates the selector keys on the front
thermostat display panel and gives selection control to the remote.

3 WIRE REMOTE

This icon is not a fault icon
but instead indicates a remote
switching device is connected
to the Pentair Temperature
Controller 7800, and has
overriding selection control
of Pentair Temperature
Controller 7800.

5 A FUSE
FOR AUX2 (PILOT DUTY ONLY)

AUX2
PUMP
PURGE MODE

5A
25O V
RELAY

5 3 1

6 4 2

10 A
25O V
RELAY
PUMP/AUX2

1 2 3
C

F
1

G VALVE
1

LIMITS
1

POWER
5

REMOTE
(AUX1)

TPROBE

A.C LOAD (PUMP/AUX2)
(PILOT DUTY ONLY)

}

NOT USED

POOL
SPA
GND

AIR PRESS

BLOWER (POWER) LINE

POOL

24 VAC

PRESS

H LIMIT

T FUSE

PV/MV
MV

PV/MV
MV
PV

4
3

1 2

24 VAC

10 A
25O V
RELAY
BLOWER

BLOWER (POWER) LINE

GND

3
2
1

IGN MODULE

SPA

TEMPERATURE
DISPLAY MODE

REMOTE POOL/OFF/SPA
THERMOSTAT SELECT SWITCH

Figure 8.

COMMON

Rev. A 1-2-02

P/N 472032

EXTERNAL
BOND LUG

AIR PRESSURE SW.

ORG

WHT

1
2

AUX2

10A
250V
RELAY

BLOWER
REMOTE
TPROBE

TFUSE
LIMITS

6 5 4 3 2 1

POWER

2 1

RED

PENTAIR 7800

AIR
PRESS SW.

TEMPERATURE
PROBE

WHT

ORG

WHT

RED

1
2

RELAY

WHT

GRN

WATER PRESSURE
SWITCH

RED

EXHAUST HIGH LIMIT
THERMAL SWITCHES

1
2
3
4
5
6

WHT

HIGH LIMIT
THERMAL SWITCHES

SPDT EXTERNAL SWITCH

RED

CHASSIS
SHEET METAL

WHT

3 2 1

GAS
VALVE

P10

4 3 2 1

IGN
MODULE

P11

5A
250V
RELAY

3 2 1

2
1
3

ORG

BLU

WHT

RED

RED
WHT
BLU

THERMAL FUSE

WHT

RED
BLU

ORG

BLK/WHT

BLK

RED
RED/WHT

GRN

WHT
YEL
BLU

BLK

WHT

(WHT)

CON-2M

GND

MV1

LO/FS

S1/240

S1/120

BURNER

HOT SURFACE
IGNITOR

GAS VALVE

WHT

TERMINATE SUPPLY SAFETY GROUND WIRE (GREEN) HERE
GROUND SCREW WITH PAINT CUTTING WASHER

1
2
3

COM

SPA

POOL

IGN MODULE

FLAME SENSOR

BLK

(BRN)

BLK

BLOWER

PUR

ORG

BLK

CON-2F

FOR 240 VAC

YEL

(BLU)

CON-2F

WHT
WHT

FOR 120 VAC

IF ORIGINAL FACTORY WIRING MUST BE REPLACED, INSTALLER MUST SUPPLY
UL OR CSA (IF CANADA) APPROVED WIRE, 18 GAUGE, 600V, 105˚ C TEMPERATURE RATING.
THERMAL FUSE WIRING MUST BE REPLACED WITH UL OR CSA (IF CANADA) APPROVED
WIRE, 18 GAUGE, 600V, 200˚ C TEMPERATURE RATING.
INTERCONNECTING WIRING TO APPLIANCE MUST CONFORM TO THE NATIONAL ELECTRICAL
CODE OR SUPERCEDING LOCAL (WIRING) CODES.

GRY

P/N 472032
1
2

WHT

MiniMax NT STANDARD ALL MODELS WIRING DIAGRAM

BLK

WHT

WHT
BLK
BLK

GRN
WHT

TERM B
BLOCK

TERM A
BLOCK

BLK

WHT

GRN

240 VAC

120 VAC

Installation (Dual Voltage Wiring)
10

MiniMax NT Standard (ALL MODELS) HSI Electronic Ignition Wiring Diagram

(DUAL VOLTAGE)

FENWAL

PUMP RELAY

Rev. A 1-2-02

Installation (Plumbing)

WATER CONNECTIONS
Reversible Inlet/Outlet Connection
The MiniMax NT Standard heater is factory
assembled with right side inlet/outlet water
connections. The inlet/outlet header can be reversed
for left side water connections without removing the
heat exchanger.
Reversing Water Connections
Tools required:
1/4 in. Screw Driver
9/16 in. Socket and Wrench
1/2 in. & 9/16 in. Open Wrench
1. Remove the right and left large inspection plates.
2. Disconnect all wires from the high-limit
switches except the short jumper wire.
3. Disconnect the pressure switch wiring.
4. Remove the temperature sensing bulb from the
inlet/outlet header. Note: If needed, you may cut
the wire ties holding them together.
5. Remove the 16 bolts holding the main inlet/
outlet head and return head in place, exchange
the heads, using the new tube seals supplied
with the heater, re-install the 16 bolts using
moderate torque.
6. Install the temperature sensing probe by passing
the wires through the hole provided on the left
side of the brace panel. Route wires through the
support bracket.
7. Reconnect all the high limit wires and the
pressure switch wiring, routing the wires
through the same hole as the thermostat sensor
wires.
8. Re-install the two large inspection plates on the
appropriate side.

VALVES
When any equipment is located below the surface of
the pool or spa, valves should be placed in the
circulation piping system to isolate the equipment
from the pool or spa.
Check valves are recommended to prevent back
siphon.

CAUTION
Exercise care when installing chemical feeders so
as to not allow back siphoning of chemical into the
heater, filters or pump.
Rev. A 1-2-02

FILTER
MANUAL
BY-PASS

CHECK
VALVE

GATE
VALVE

Figure 9.

CHECK
VALVE
FROM
POOL

PLUMBING CONNECTIONS
The MiniMax NT Standard heater has the unique
capability of direct schedule 40 PVC plumbing
connections. A set of bulkhead fittings is included with
the MiniMax NT Standard to insure conformity with
Pentair’s recommended PVC plumbing procedure.
Other plumbing connections can be used.

CAUTION
Before operating the heater on a new installation,
turn on the circulation pump and bleed all the air
from the filter using the air relief valve on top of the
filter. Water should flow freely through the heater.
Do not operate the heater unless water in the pool/
spa is at the proper level.

MANUAL BY-PASS
Where the flow rate exceeds the maximum 120
GPM, a manual bypass should be installed and
adjusted. After adjustments are made, the valve
handle should be removed to avoid tampering.
Model

PLUMBING

PUMP

TO
POOL

POOL
HEATER

Min. (GPM) Max. (GPM) *

200

120

250

120

300

120

400

120

* Do not exceed the maximum recommended
flow rate for the connecting piping.

BELOW POOL INSTALLATION
If the heater is below water level, the pressure
switch must be adjusted. This adjustment must be
done by a qualified service technician. See Page 19,
Figure 19.
P/N 472032

Installation (Gas Line)

GAS CONNECTIONS

Pipe Sized For Length Of Run In Equivalent Feet

GAS LINE INSTALLATIONS
Model
Before installing the gas line, be sure to
200
check which gas the heater has been
250
designed to burn. This is important
300
because different types of gas require
400
different gas pipe sizes. The rating plate
on the heater will indicate which gas the
heater is designed to burn. Table 1., shows which
size pipe is required for the distance from the gas
meter to the heater. The table is for natural gas at a
specific gravity of .65 and propane at a specific
gravity of 1.5.

When sizing gas lines, calculate three (3) additional
feet of straight pipe for every elbow used.
When installing the gas line, avoid getting dirt,
grease or other foreign material in the pipe as this
may cause damage to the gas valve, which may
result in heater failure.
The gas meter should be checked to make sure that
it will supply enough gas to the heater and any other
appliances that may be used on the same meter.

1/2 in.

3/4 in.

1 in.

1¼ in.

Nat

The heater and its gas connection must be leak
tested before placing the heater in operation. Do not
use flame to test the gas line. Use soapy water or
another nonflammable method.
A manual main shut-off valve must be installed
externally to the heater.

WARNING
Do not install the gas line union inside the heater
cabinet. This will void your warranty.

1½ in.

2 in.

Nat

20'

30'

80'

125' 250' 450' 600'

10'

20'

50'

70'

150' 250' 500' 600'

10'

30'

50'

100' 200' 350' 400' 600'

10'

20'

60'

Nat

100' 150' 200' 450' 400'

REGULATED MANIFOLD PRESSURE TEST
1. Attach the manometer to the heater jacket.
2. Shut off the main gas valve.
3. Remove 1/8 in. NPT plug on the outlet side of the
valve and screw in the fitting from the manometer kit.
4. Connect the manometer hose to the fitting.
5. Turn on the heater.
6. The manometer must read 4 in. WC for natural gas
or 11 in. WC for propane, while operating.
7. For adjustment, remove the Regulator Adjustment
Cap and using a screwdriver turn the screw clockwise to increase - counterclockwise to decrease gas
pressure.
Regulator Adjustment Cap
1/8" NPT Plug
(Inlet Press)

The gas line from the meter will usually be of a
larger size than the gas valve supplied with the
heater. Therefore a reduction of the connecting gas
pipe will be necessary. Make this reduction as close
to the heater as possible.
The heater and any other gas appliances must be
disconnected from the gas supply piping system
during any pressure testing on that system, (greater
that ½ PSIG).

Table 1.

OFF
1/8" NPT Plug
(Manifold Press)

Figure 10.

CAUTION
The use of Flexible Connectors (FLEX) is NOT
recommended as they cause high gas pressure drops.

MINIMAX NT STANDARD GAS PRESSURE REQUIREMENTS*
Natural
Maximum inlet gas pressure 10 in. WC
Minimum inlet gas pressure **5 in. WC
Normal manifold pressure
4 in. WC

Propane
14 in. WC
12 in. WC
11 in. WC

*All Readings are taken with the heater fired. Any adjustments
or readings made with heater off will give incorrect readings.
** 6 in. WC for 400 model

P/N 472032

Rev. A 1-2-02

Installation (Indoor)

INDOOR VENTING—General Requirements
The vent pipe must be the same size or larger. The MiniMax NT Standard heaters are capable of a 360-degree
discharge rotation and operate with a positive vent static pressure and with a vent gas temperature less than
400° F. The total length of the horizontal run must not exceed the length that is listed below in the tables.

Please note the allowable vent runs for each stack pipe diameter are different and can not be exceeded.
Note that each 90-degree elbow reduces the maximum horizontal vent run by 8 feet and each 45-degree elbow
in the vent run reduces the maximum vent run by 4 feet. See the tables below for the maximum vent lengths
using a 90-degree and 45-degree elbows. The MiniMax NT Standard induced-draft pool and spa heater uses
positive pressure to push flue gases through the vent pipe to the outside. This requires a completely sealed vent
system—single wall vent pipe with sealed-seams and joints may be used. Flue gases under positive pressure
may escape into the dwelling with any cracks or loose joints in the vent pipe, or improper vent installation.
The vent pipe must be of a sealed-seam construction such as those listed for use with category III appliances.
Alternately, single wall or double-wall type B duct which has had duct seams and joints permanently sealed
using cements or other suitable means which are rated for use at the flue gas temperatures of 325° F. and are
permanent are acceptable. The use of listed thimbles, roof jacks and/or side vent terminals are required; and the
proper clearances to combustible materials must be maintained in accordance with type of vent pipe employed—
in the absence of a clearance recommendation by the vent pipe manufacturer, the requirements of the Uniform
Mechanical Code should be met. The ventilation air requirements for the MiniMax NT Standard heater and
can be found on page 15. It is recommended that vent runs over 18 feet be insulated to reduce condensation
related problems and/or the use of a condensate trap in the vent run close to the heater may be necessary in
certain installations such as cold climates. The MiniMax NT Standard is suitable for through-the-wall venting.
Recommended sources for Side-wall vent hood terminals include: The Field Controls Co. (2308 Airport Road,
Kingston, NC 28501, (800)742-8368) and Tjernlund Products Inc. (1601 Ninth Street, White Bear Lake, MN
55110, (800) 255-4208)—consult manufacturer for model information and availability.

CAUTION
Do NOT combine exhaust vent pipes to a common exhaust vent in multiple unit installations. Run separate vent pipes.

45 ft. Maximum Vent Run, 5 in. O.D. vent (Equiv. ft.)
Additional 90° elbows
after first elbow

Additional 45° elbows
after first elbow

22 ft. Maximum Vent Run, 4 in. O.D. vent (Equiv. ft.)
Additional 90° elbows
after first elbow

Additional 45° elbows
after first elbow

Quantity

Reduced Max.

Quantity

Reduced Max.

Quantity

Reduced Max.

Quantity

Reduced Max.

1 (2 total)

(2 total)

1 (2 total)

14 ft.

(2 total)

18 ft.

2 (3 total)

(3 total)

2 (3 total)

—

(3 total)

14 ft.

3 (4 total)

(4 total)

3 (4 total)

—

(4 total)

—

Rev. A 1-2-02

P/N 472032

;;;
;;;
;;;

Installation (Indoor)

INDOOR INSTALLATION (USA ONLY)
OUTDOOR SHELTER INSTALLATION (CANADA)
See page 15 for (Indoor) Vent Adaptors

10 ft.

Ridge

Vent
Cap

2 ft. min.

3 ft. min.

All products of combustion and vent gases must be
completely removed to the outside atmosphere through
a vent pipe which is connected to the stack adaptor. A
vent pipe extension of the same size must be connected
to the indoor stack adaptor and extended at least 2 feet
higher than highest point of the roof within a 10 foot
horizontal radius, and at least 3 feet higher than the
point at which it passes through the roof, or as permitted
by local code; see Figures 11 and 12. The vent should
terminate with an approved vent cap (weather cap) for
protection against rain or blockage by snow. Doublewall vent pipe and an approved roof jack shall be
employed through the roof penetration.

Roof
Jack

Chimney

Figure 11.

VENT CAP AND
RISER FURNISHED
BY INSTALLER

The heater must be located as close as practical to a
chimney or gas vent.

AIR SUPPLY
VENTILATION

CAUTION

AIR SUPPLY
GAS COMBUSTION

The heater should be installed at least 5 feet away
from the pool or spa.
The heater must be placed in a suitable room on a noncombustible floor or on a non-combustible base and in
an area where leakage from heat exchanger or water
connections will not result in damage to the area
adjacent to the heater or the structure. When such
locations cannot be avoided, it is recommended that a
suitable drain pan with adequate drainage, be installed
under the heater. The pan must not restrict air flow.

OPTIONAL SIDE WALL VENT NT

The heater should not be installed closer than 6
inches to any fences, walls or shrubs at any side or
back, nor closer than 18 inches at the plumbing side.
A minimum clearance of 24 inches must be
maintained at the front of the heater.

Installations in basements, garages, or underground
structures where flammable liquids may be stored must
have the heater elevated 18 inches from the floor using
a non-combustible base. The following minimum
clearances from combustible materials must be
provided.

Remaining
Ceiling Clearance

Front

Back

Top

18 in.

24 in.

6 in.

18 in.*

DOOR

Water Connection

Side

Figure 12.

24"

18"

*To ceiling or roof.
Figure 13.

P/N 472032

Rev. A 1-2-02

Installation (Indoor)

NOTE
The heater requires two uninterrupted air supply
openings; one for ventilation and one to supply
oxygen for proper gas combustion. The air supply
openings should be sized according to Table 2.

b) Construct a non-combustible base from masonry
blocks as illustrated, see Figure 14.
BASE FOR USE ON COMBUSTIBLE FLOORS

Air supply requirements below apply to all
MiniMax NT Standard heaters*.

REQUIRED AIR SUPPLY
Model

Air for Combustion
Sq. In.

Air Ventilation
Sq. In.

200

250

300

400

.
in
M

SHEET METAL

Table 2.

*NOTE
The openings listed in Table 2. are free open vent
area—if the vents incorporate restrictive louvers,
the vent openings must be increased to
compensate for the area blocked by the louvers (or
grills).

INSTALLATION ON FLOORS CONSTRUCTED
OF COMBUSTIBLE MATERIALS

BLOCKS

Figure 14.

CAUTION
Chemicals should not be stored near the heater
installation. Combustion air can be contaminated by
corrosive chemical fumes which can void the warranty.

INDOOR VENT ADAPTORS
(FITS ALL MODELS)
The proper draft hood and adapter must be installed on
the heater as shown below and on pages 13 and 14:

The heater may be placed on a “combustible floor”
using either of the two methods listed below:
a) Use Listed Factory Non-combustible Base Kit
for use on combustible floors.
Model

Non-Combustible Base Kit

200

471961

250

460509

300

471960

400

460508

HOLLOW MASONARY BLOCKS, NOT LESS THAN 4" THICK
(LAID WITH ENDS UNSEALED AND JOINTS MATCHED
FOR AIR CIRCULATION). COVER BLOCKS WITH
24 GA. (MIN.) GALVANIZED SHEET METAL.

Part No.

Vent Dia.

460506

4 in.

460507

5 in.
Indoor Vent
Adaptor

Figure 15.
Rev. A 1-2-02

P/N 472032

Detail H

Chimney

3 ft. min.

;;
;;

2 ft. min.

Vent
Cap

may use a single wall vent pipe with
permanently sealed seams and joints.

must be suitable for use with category III
appliances which have flue gas temperatures
of less than 400 deg. F.

must be the same diameter as the
vent connector.

Vent pipe extension:

L must terminate with an approved (listed)
roof jack, storm collar, and vent/weather cap.

K must use a double-wall vent pipe through
the roof penetration.

J must extend at least 3 ft. higher than the
point at which it passes through the roof,
or as permitted by local code.

Vent for roof penetration installations:

Ridge

10 ft.

vent terminated at
least 24" above
any object within 10 ft.

Air Supply
Combustion

Air Supply
Ventilation

1' min.

Vent Hood

1' min.
above grade

Recommended sources for
side wall Vent Hood; see page 15,
Section Venting.

Vent Hood

(Table 2. on page 15.)

G See Air Supply Requirements Table.

Air Supply

Figure 16.

must be located the following distances away from any door, window, or gravity air inlet:
D 4 ft. below
E 4 ft. horizontally
F 1 ft. above

A must be not less than 7 ft. above public walkways.
B must be at least 3 ft. above any outside air intake located within a 10 ft. radius.
must NOT be within 3 ft. of an inside corner of the structure.
C must be at least 1 ft. above grade.

Vent termination for side wall installations:

Walkway

Vent Hood

INDOOR INSTALLATIONS
MINIMAX NT STANDARD VENTING GUIDELINES

Installation (Indoor)
16

Rev. A 1-2-02

Installation (Outdoor)

VENTILATION
OUTDOOR INSTALLATION ONLY (Outdoor Shelter Installation in Canada, see page 14)
For outdoor installation with built in vent, the heater must be placed in a suitable area on a level, noncombustible
surface. Do not install the heater under an overhang with clearances less than 3 feet from the top of the heater. The
area under an overhang must be open on three sides.

IMPORTANT!
In an outdoor installation it is important to ensure water is diverted from overhanging eves with a
proper gutter/drainage system. The heater must be set on a level foundation for proper drainage.
Maintain minimum clearances as indicated below. Install a minimum of 4 feet below, and 4 feet horizontally from
any opening to a building, see Figure 17.

IMPORTANT!
When locating the heater, consider that high winds can roll over or deflect off adjacent buildings
and walls. Normally, placing the heater at least three feet from any wall will minimize downdraft.

NOTE
This unit shall not be operated outdoors at temperatures below -20o F. for natural gas.

OUTDOOR INSTALLATION
MINIMAX NT VENTING GUIDELINES

4'
3'
4'

B
Property Line

Walkway
E

Check local building codes
for setback requirements.

Figure 17.

Vent Termination:
Must be not less than 7 ft. above public walkways.
A Must be at least 3 ft. above any forced
air inlet located within a 10 ft. radius.
Must be located the following distances away
from any door, window, or gravity air inlet:
B 4 ft. below, or
C 4 ft. horizontally, or
D 1 ft. above

Rev. A 1-2-02

P/N 472032

Basic Operation

GENERAL DESCRIPTION
The MiniMax NT Standard Pool and Spa Heater is a fan-assisted induced draft appliance. The MiniMax NT
Standard is available in 200,000, 250,000, 300,000 and 400,000 btu/hr. capacities and are certified for both
indoor and outdoor installations.
The MiniMax NT Standard is designed to operate both in stackless outdoor installations and in indoor stack
vent installations—the indoor installation may be made using Kit 460506 or 460507; see pages 6 and 15,
vertical vent pipe or with a horizontal vent pipe and a Listed side-wall vent.

BASIC SYSTEM OPERATION
TO OPERATE HEATER
1.

Start pump, make sure the pump is running and is primed, to close water pressure switch and
supply power to heater.

Set thermostat to lowest setting by using up/down arrow keys. See page 22.

Push the off key on the Pentair temperature controller 7800 (the amber “off “ led will illuminate).
See page 21.

Open the access doors.

Push in the gas control knob slightly and turn the knob clockwise to “OFF”.
See page 5 for Instructions.

Wait (5) minutes to clear out any gas. If you then smell gas STOP. Follow the safety information
(stated earlier in the lighting instructions section). If you don’t smell gas, go to the next step.
See page 5 for Instructions.

Turn the knob on the gas control counter clockwise to the “ON” position. See page 5 for Instructions.

Replace the doors.

Push either the “Pool” or “Spa” key to start the heater. NOTE: “Pool” key is Factory set at 78° F. and
“Spa” key is set at 104° F.

10. Set the thermostat if needed by using the up/down arrows to set the desired temperature.
a. Fan motor starts, which closes draft proving switch.
b. Ignition module is energized after fan prepurge cycle is completed approximately 2 minutes.
c. Check for powering up the (glow coil) hot-surface ignitor by viewing through the opening holes
on the face plate.
11.

The ignitor will warm up and then gas valve opens to ignite the main burners.

12. Heater will operate until desired temperature is reached.

P/N 472032

Rev. A 1-2-02

Basic Operation

SAFETY CONTROLS
AIR PRESSURE (FAN) SWITCH
The air pressure switch is a safety device used to insure that the blower (fan) is operating and has been designed
to monitor the vacuum (negative) pressure within the blower housing. The air pressures switch is factory set
and is in the ignition module circuit—the ignition module does not operate unless the air pressure switch and
all safety switches are closed.

Figure 18.

AIR PRESSURE SWITCH

WATER PRESSURE SWITCH
The water pressure safety switch closes when there is a sufficient flow of water to the heat exchanger to safely
operate the heater. The switch operation must be verified during initial operation of the heater after installation—
the switch is set at 1 PSIG and the switch contacts must not be closed in the absence of water flow. NOTE: See,
Below Pool Level Installation instructions on page 11. The switch may remain closed with no water flow if
there is more than a 3 feet elevation difference between the heater (heat exchanger) and the pool water line—
if this is the case, the water pressure switch must be reset to maintain open switch contacts with no water flow.
NOTE
If the pool is more than one floor above or one floor below the heater, the pressure switch may have to be
replaced with a flow switch.
Figure 19.

Adjustment Knob

Typical Water Pressure Switch
Rev. A 1-2-02

P/N 472032

Basic Operation

SAFETY CONTROLS, (cont’d.)
IGNITION MODULE
The Ignition Module is microprocessor based and operates on 24 VAC supplied by the transformer. The
control utilizes a microprocessor to continually and safely monitor, analyze, and control the proper operation
of the gas burners. The module with the presence of the flame sensor/ignitor or remote sensor, using flame
rectification, allows the heater to operate.

HIGH LIMITS
A “High Limit”, is a safety device that opens the electrical circuit and shuts off the heater based on a
temperature set point within the “High Limit Device”. The MiniMax NT Standard series of heaters contains
three (3) high limit devices, two (2) are located on the main inlet / outlet header, one sensing the inlet water
temperature and one sensing the outlet water temperature. The third high limit is located on the exhaust
outlet and senses the temperature of the flue gas.

OPERATION OF IGNITION MODULE
HEAT MODE
• When a call for heat is received from the thermostat supplying 24 VAC to the “W” module terminal, the
control will perform a self check routine for up to four seconds and begins the safety timing ignition
sequence. After the fan prepurge cycle, the hot surface ignitor is activated for a heat-up period followed
by energization of the gas valve for the trial for ignition period.
• When flame is detected during the trial for ignition, the ignitor is deactivated and the gas valve remains
energized. The thermostat and main burner flame are constantly monitored to assure the system
continues to operate properly. When the thermostat is satisfied and the demand for heat ends, the main
valve is de-energized immediately.

FAILURE TO LIGHT-LOCK OUT
Should the main burner fail to light, or flame is not detected during the trial for ignition period, the control
will go into lockout and the gas valve will be turned off immediately. The thermostat controller will display
a flame failure error (icon/service LED) and recovery from lockout requires a manual reset by either
resetting the 7800 Thermostat or removing 24 VAC from the system by turning off main power switch
(located on the junction box behind right door) for a period of 5 seconds.

FLAME FAILURE—RE-IGNITION
If the established flame signal is lost while the burner is operating, the control will respond within 1 second.
The gas valve is de-energized and the control starts a new ignition sequence in an attempt to relight the
burner. If the burner does not relight, the control will go into lockout, requiring a manual reset.

P/N 472032

Rev. A 1-2-02

Thermostat (Programming & Layout)

MINIMAX NT STANDARD PENTAIR TEMPERATURE CONTROLLER 7800
(See Figure 20, for keypad and Pentair Temperature Controller 7800 layout details.)

GENERAL
The MiniMax NT Standard Pentair Temperature Controller 7800 is the heart of the control
system. It controls all functions of the heater after first verifying that all safety controls
are functioning normally. If a malfunction is detected, the Pentair Temperature Controller
7800 will flag the error with both the RED “Service” LED lighting and a corresponding
LCD icon appearing on the Pentair Temperature Controller 7800, pin pointing the affected
safety control(s). NOTE: The exception is the AUX (REMOTE) LCD icon which appears
when a REMOTE Control (or Remote Switch) is connected to the Pentair Temperature
Controller 7800, which overrides the “POOL” and “SPA” keypads on the control, giving
“ON” selection control to the REMOTE.

BASIC THERMOSTAT OPERATION

The Pentair Temperature Controller 7800 comes pre-programmed for use with the spa
temperature set at 104° F. and the pool temperature set for 78° F.— and with default
display mode set to display degrees F. (this may be adjusted to display in degrees C. with
jumper on back of board), see Figure 20.
You need not do anything further to enjoy your heater other than set it in the pool or spa mode by depressing the key
located under the corresponding “POOL” or “SPA” LED light. The LED above the selection will light and the
corresponding “POOL” or “SPA” LCD icon on the display will appear.

NORMAL OPERATION (NO REMOTE)
Each temperature setting in either POOL or SPA mode is settable independently.
If the Factory’s presetting of 78° F. for “Pool” and 104° F. for “Spa” is not desirable, you may adjust these settings. See
page 22 for changing the Factory Temperature Settings. To set the temperature while in SPA mode press the TEMP UP
key (with UP arrow) to increase or TEMP DOWN (with DOWN arrow) to decrease the set temperature to that desired.
NOTE: The left hand display indicates the current real-time temperature. To set the temperature for POOL mode, first
switch to POOL mode by depressing the “POOL” key and repeat the temperature setting procedure in this example. The
Pentair Temperature Controller 7800 remembers the last set temperature for both the POOL and SPA mode and you may
cycle between the two settings with the POOL and SPA selector keys.
In NORMAL operation, pressing the MODE key allows you the cycle between the right-hand display showing the SET
TEMP for the currently active POOL or SPA or the TIME.

(Pentair Temperature Controller 7800 Layout)
FLASH IN PROGRAM MODE

DAY ICON
DISPLAY IN TIME MODE ONLY

ALTERNATE DISPLAY C or F.

F = FAHRENHEIT
C = CELSIUS

ALTERNATE DISPLAY

F = FAHRENHEIT
C = CELSIUS
P = P.M.
BLANK = A.M.

SYSTEM
NORMAL

POWER

SERVICE

HEAT
CURRENT TEMP

SET TEMP/TIME

POOL OR SPA
(DISPLAY ALTERNATELY
ON LCD TO SHOW ACTIVE SELECTION)

IGN

H-LMT

PRESS

FAN

AUX

TFUSE

FAULT CONDITION LCD ICONS

SET

POOL
PROGRAM

MODE

Figure 20.
Rev. A 1-2-02

OFF

TEMP

SPA
STEP

TEMP

KEYPAD SWITCHES

P/N 472032

Temperature & Time Setting (Programming)

TO CHANGE THE FACTORY TEMPERATURE SETTINGS:
1. Before changing the temperature, make sure the “Temperature” is in the right window, see pages 22
and 23, if “Time” is displayed, press the MODE key to change to the “Temperature Mode”.
SET
PROGRAM
MODE

2. To change the Pool Temperature setting, press the POOL key.

POOL

OFF

SPA

3. To Raise or Lower the Pool Temperature setting, press the proper TEMP key
until the desired setting is displayed.

TEMP
STEP

NOTE: During Programming of the Pool Temperature, the two buttons on the
right are used to
or
the display setting numbers.
Increase
Decrease
Raise
Lower

(

) (

TEMP

)

NOTE: Pool Temperature is now set.
4. You can leave the right window displaying the set “Temperature” or by pressing
the MODE key, you can return to the “Time” Mode.

TEMP
STEP

NOTE: To re-set the Spa Temperature, follow the above steps 1. through 4.
while in the “Spa Heating” Mode.

TEMP

TIME SETTING
1. Make sure heater is turned “OFF” and not in the POOL or SPA “ON” Mode.
POOL

OFF

SPA

2. Place the Controller in Programming Mode by depressing the SET and MODE buttons at the same time.
SET
PROGRAM
MODE

NOTE: During Programming of the Time Setting, the two buttons on the right
are used to

P/N 472032

(

) (

Increase
Raise

)

Decrease
the display setting numbers.
Lower

TEMP
STEP
TEMP

Rev. A 1-2-02

Time Setting (Programming)

TIME SETTING, (cont’d.)
3. The first setting, once you enter the Programming Mode, will be the Day. The
Day icon will be flashing. Use the UP or DOWN arrow TEMP keys to locate
the appropriate day, then press the SET key. The Day is now set and the Hour
Time icon will start to flash.

TEMP
STEP
TEMP

SET
PROGRAM
MODE

4. With Hour Time icon flashing, use the UP/DOWN arrow TEMP keys. Set the
Hour to the proper time, “P” will show to the right for PM, and blank for AM.
Once the proper Hour is visible, press the SET key. The Minute icon’s will
now start flashing.

TEMP
STEP
TEMP

SET
PROGRAM
MODE

5. With the Minute icon’s flashing use the UP/DOWN arrow TEMP keys and
select the proper Minute setting, then press the SET key. The Day and Time are
now set and the Day icon will be flashing.

TEMP
STEP
TEMP

SET
PROGRAM
MODE

6. Press the SET and MODE keys at the same time to return to the Operational Mode.
SET
PROGRAM
MODE

NOTE
During the programming of the CLOCK/DAY function, you touch only the MODE key and a D appears
in the upper left corner of the “Current Temperature Display Area”, this represents a delay function and
will be used for future functions and accessories to the MiniMax NT Standard. When the D appears,
simply stop the programming, “do NOT touch any key for 30 seconds”, the controller will automatically
return to the operating mode, now by pressing the “SET & MODE keys” at the same time, you will
re-enter the programming function, and the D icon will disappear.

Rev. A 1-2-02

P/N 472032

Maintenance

MAINTENANCE INSTRUCTIONS
It is recommended that you check the following items at
least every six months and at the beginning of every
swimming season.
1. Examine the venting system. Make sure there are no
obstructions in the flow of combustion and
ventilation air.
2. Visually inspect the main burner and the hot surface
ignitor. The normal color of the flame is blue. When
flame appears yellow, burners should be inspected
and cleaned. Check ignitor for damage.
3. Keep the heater area clear and free from
combustibles and flammable liquids.

STANDARD
Figure 21.

ENERGY SAVING TIPS
1. If possible, keep pool or spa covered when not in
use. This will not only cut heating costs, but also
keep dirt and debris from settling in the pool and
conserve chemicals.
2. Reduce the pool thermostat setting to 78° F. or
lower. This is accepted as being the most healthy
temperature for swimming by the American Red
Cross.
3. Use an accurate thermometer.
4. When the proper maximum thermostat settings have
been determined, tighten the thermostat knob
stopper.

Pressure Relief Valve
In some installations, a pressure relief valve (PVR) is
required on the
MiniMax NT
Standard. To install
a PRV, carefully drill
FOR PRV
INSTALLATION
a 3/8 in. hole in
DRILL THRU
center of 3/4 in.
THE NPT PORT
NPT port (on main
header) being
careful to drill only
thru wall at bottom
of 3/4 in. NPT port Figure 22.
and no deeper—
now thread in the 3/4 NPT PRV. NOTE: (A.S.M.E.
version varies from illustration. It is of bronze
construction, and is supplied with the A.S.M.E. Section
IV, pressure relief valve pre-installed at factory.) Test the
relief valve at least once a year by lifting up lever.
5. Set time clock to start circulation system no earlier
than daybreak. The swimming pool loses less heat at
this time.
6. For pools that are only used on the weekends, it is
not necessary to leave the thermostat set at 78° F.
Lower the temperature to a range that can be
achieved easily in one day. Generally, this would be
10° F. to 15° F., if pool heater is sized properly.
7. During the winter or while on vacation, turn the
heater off.
8. Set up a regular program of preventative
maintenance for the heater each new swimming
season. Check heat exchanger, controls, burners,
operation, etc.

SPRING AND FALL OPERATION
If the pool is being used occasionally, do not turn the heater
completely off. Set the thermostat down to 65° F. This

will keep the pool and the surrounding ground warm
enough to bring the pool up to a comfortable swimming
temperature in a shorter period of time.

WINTER OPERATION
If the pool won't be used for a month or more, turn the
heater off at the main gas valve. For areas where there is
no danger of water freezing, water should circulate through
the heater all year long, even though you are not heating
your swimming pool. The MiniMax NT Standard should
not be operated outdoors at temperatures below 0° F. for
propane and -20° F. for natural gas. Where freezing is
P/N 472032

possible, it is necessary to drain the water from the heater.
This may be done by opening the drain valve, located at
the inlet/outlet header (see Figure 22.), allowing all water
to drain out of the heater. It would be a good practice to
use compressed air to blow the water out of the heat
exchanger. (See additional notes under Important Notices
in Introduction.)
Rev. A 1-2-02

Maintenance (Water Treatment)

CHEMICAL BALANCE

RULE: 7.4 to 7.6 is a desirable pH range. It is essential
to maintain correct pH, see Table 4.

POOL AND SPA WATER

If pH becomes too high (over alkaline), it
has these effects:

Your Pentair Pool Products pool heater was designed
specifically for your spa or pool and will give you many
years of trouble-free service, provided you keep your
water chemistry in proper condition.
Three major items that can cause problems with your
pool heater are: improper pH, disinfectant residual, and
total alkalinity. These items, if not kept properly
balanced, can shorten the life of the heater and cause
permanent damage.

CAUTION
Heat exchanger damage resulting from chemical
imbalance is not covered by the warranty.

WHAT A DISINFECTANT DOES
Two pool guests you do not want are algae and bacteria.
To get rid of them and make pool water sanitary for
swimming - as well as to improve the water's taste, odor
and clarity - some sort of disinfectant must be used.
Chlorine and bromine are universally approved by health
authorities and are accepted disinfecting agents for
bacteria control.

WHAT IS A DISINFECTANT
RESIDUAL?
When you add chlorine or bromine to the pool water, a
portion of the disinfectant will be consumed in the
process of destroying bacteria, algae and other oxidizable materials. The disinfectant remaining is called
chlorine residual or bromine residual. You can determine
the disinfectant residual of your pool water with a reliable
test kit, available from your local pool supply store.
You must maintain a disinfectant residual level adequate
enough to assure a continuous kill of bacteria or virus
introduced into pool water by swimmers, through the air,
from dust, rain or other sources.
It is wise to test pool water regularly. Never allow
chlorine residual to drop below 0.6 ppm (parts per
million). The minimum level for effective chlorine or
bromine residual is 1.4 ppm.
pH - The term pH refers to the acid/alkaline balance of
water expressed on a numerical scale from 0 to 14. A test
kit for measuring pH balance of your pool water is
available from your local pool supply store; see Table 3.

pH Chart

Table 3.
Strongly Acid
0

Neutral
4

Strongly Alkaline
10

Muriatic Acid has a pH of about 0. Pure water is 7
(neutral). Weak Lye solution have a pH of 13-14.
Rev. A 1-2-02

1. Greatly lowers the ability of chlorine to destroy
bacteria and algae.
2. Water becomes cloudy.
3. There is more danger of scale formation on the
plaster or in the heat exchanger.
4. Filter elements may become blocked.

If pH is too low (over acid) the following
conditions may occur:
1. Excessive eye burn or skin irritation.
2. Etching of the plaster.
3. Corrosion of metal fixtures in the filtration and
recirculation system, which may create brown, blue,
green, or sometimes almost black stains on the
plaster.
4. Corrosion of copper in the heater, which may cause
leaks.
5. If you have a sand and gravel filter, the alum used as
a filter aid may dissolve and pass through the filter.

CAUTION: Do not test for pH when the chlorine
residual is 3.0 ppm or higher, or bromine residual
is 6.0 ppm or higher. See your local pool supply
store for help in properly balancing your water
chemistry.
RULE: Chemicals that are acid lower pH. Chemicals
that are alkaline raise pH.

pH Control Chart

Table 4.
6.8

7.0

7.2

Add Soda, Ash or
Marginal
Sodium Bicarbonate

7.4 7.6

7.8

Ideal

Marginal

8.0

8.2

8.4

Add Acid

ALKALINITY High - Low:
"Total alkalinity" is a measurement of the total amount
of alkaline chemicals in the water, and control pH to a
great degree. (It is not the same as pH which refers
merely to the relative alkalinity/acidity balance.) Your
pool water's total alkalinity should be 100 - 140 ppm to
permit easier pH control.
A total alkalinity test is simple to perform with a reliable
test kit. You will need to test about once a week and
make proper adjustments until alkalinity is in the proper
range. Then, test only once every month or so to be sure
it is being maintained. See your local pool dealer for
help in properly balancing the water chemistry.
P/N 472032

Troubleshooting—Normal Operation Sequence of Heater

NORMAL OPERATION SEQUENCE
(Refer to Figure 20 of Pentair Temperature Controller 7800 keyboard)
The heater features a fully automated firing start-up and shutdown sequence under the control of the
MiniMax NT Standard Pentair Temperature Controller 7800.
Now that the heater has been properly installed and wired for either remote operation or local operation, and
you have setup the Pentair Temperature Controller 7800 temperature setpoints as described earlier in manual
in Thermostat section, the following is the normal operating sequence when the heater turns on the and the
thermostat calls for heat for the pool or spa.
1. The fan will start beginning the heater’s safety prepurging cycle which lasts for 1 minute. If at anytime
during the prepurge cycle the Pentair Temperature Controller 7800 detects that a safety control is not
working due to either a safety control malfunction or other unsafe condition the firing sequence will stop
until the unsafe condition is removed— “the fault icon related to the problem will illuminate”.
2. After proper completion of the prepurge cycle, the hot surface ignitor (glow coil) will turn on (preheat)
for 40 seconds. Once the 40 seconds is passed, the main gas valve will open and the heater will fire. At
this time, if flame is not safely established as detected by the flame sensing circuit, the ignition module
and Pentair Temperature Controller 7800 will shut down and will display an ignition fault and luminate
the red service light. Please note that on initial firing of heater when gas supply piping is full of air or
after long period of non-operation of the heater it is normal for the first ignition attempt to not complete.
To clear the fault condition power to the Pentair Temperature Controller 7800 must be cycled to reset
system. If heater continues to fail to light have heater inspected by a qualified service person before
placing heater back in service.
Insufficient waterflow (pump icon displays), excessive water temperature (high limit icon) cause a
“soft-lockout” of the firing sequence—which means if the cause of the problem clears by itself (or with
human intervention ie., turning on pump, etc.) such as a slow to prime water pump finally pumping
adequate waterflow causing the water pressure (safety) switch to close, the ignition sequence
automatically restarts again.
The other category of fault conditions lead to a “hard lockout” of the firing sequence which require a
qualified service person to correct before the heater is returned to service. In “hard lockout” the heater
must be manually reset (by toggling power to Pentair Temperature Controller 7800) after correction of
the fault condition.
3. After normal firing of the heater (main burners) the heater will continue to operate until the
temperature setpoint is reached (thermostat satisfied). As the pool/spa loses heat the heater will refire
and continue to operate cycling automatically to maintain the selected temperature setpoint for either
the pool or spa. If at anytime during the firing of the heater an unsafe condition is detected the
heater will stop firing and an automatic safe shutdown sequence will begin. Investigate and have
corrected the cause of the abnormal firing termination before placing heater back in operation.

Please Note: During the firing of the heater, you decide to change to the pool or spa selection by
depressing the selector key for “POOL” or “SPA”, the heater will first acknowledge the new selection by
flashing the new selection’s corresponding selection LED “POOL” or “SPA”, however, the heater will first
complete a safe shutdown sequence before automatically switching to the new selected setting and safely
initiating a new firing sequence using the new temperature setpoint. During this automatic crossover
sequence the keyboard on the Pentair Temperature Controller 7800 will not accept any further keying until
the cycle completes—the exception is you may still stop the heater with the “OFF” key.
P/N 472032

Rev. A 1-2-02

Troubleshooting—Normal Operation of Heater

SYSTEM
NORMAL

POWER

SERVICE

HEAT
CURRENT TEMP

SET TEMP/TIME

POOL OR SPA
(DISPLAY ALTERNATELY
ON LCD TO SHOW ACTIVE SELECTION)

IGN

H-LMT

PRESS

FAN

AUX

TFUSE

FAULT CONDITION LCD ICONS

SET

POOL

OFF

TEMP

SPA

PROGRAM

STEP

MODE

TEMP

Figure 23.

Illustration of Pentair Temperature Controller 7800 with all fault icons displayed for clarity.

SERVICE CHECKS—IGNITION MODULE
Service Checks

Rev. A 1-2-02

Symptom

Cause/Cure

1. Dead

A.
B.
C.
D.

2. Thermostat on—no ignition

A. Miswired
B. Bad thermostat no voltage at terminal W

3. Valve on, no ignitor

A. Defective ignitor
B. Miswired
C. Bad control (check voltage at ignitor)

4. Ignitor on, no valve

A. Valve coil open
B. Open valve wire
C. Bad control (check voltage between V1 & V2)

5. Flame okay during TFI,
no flame sense (after TFI)

A.
B.
C.
D.

Miswired
Transformer bad
Fuse/Circuit breaker bad
Bad control (check LED for steady on)

Bad ignitor
Bad S1 wire
Poor ground at burner
Poor flame (check flame current)

P/N 472032

Troubleshooting & Service

LEGEND OF FAULT ICONS AND TYPE OF PROBLEMS FLAGGED

This fault icon displays whenever there is an unexpected loss of flame.
This condition may arise from air in gas supply line or malfunction of flame
detection circuit or related hardware. This is a hard lockout condition
requiring a manual reset to clear.

This fault icon displays whenever one or more of safety temperature limit
switches open to flag an excessive temperature condition. This is a soft
lockout condition and if the condition clears the fault icon will clear and
normal operation of heater will proceed.

This fault icon displays whenever the thermal fuse has opened due to a flame
roll-out or other abnormal condition causing excessive temperatures in the
cabinet. The cause of the fault must be corrected and the one-shot fuse
replaced before icon can be cleared.

This fault icon displays whenever there is a failure of either the low gas
pressure switch (due to low pressure or switch failure) or additionally the fan
and/or air pressure switch circuit has failed resulting in an open safety circuit.
The nature of these faults are mission critical for the safe operation of the
heater and result in a hard lockout. The cause of the fault must be corrected
and the heater will require a manual reset by toggling the power supplied to
the 7800 Controller to clear the fault.

This fault icon displays whenever insufficient waterflow causes the water
pressure switch to fail to close. This is a soft lockout condition and will clear
by itself if the waterflow is restored. The icon will then clear and if the heater
was attempting to fire the cycle will restart and continue.

P/N 472032

Rev. A 1-2-02

Troubleshooting - General
Possible Cause

Remedy

Heater will not come on
Automatic ignition system fails

Check if electrical connections are
correct and securely fastened –
If YES, call serviceperson.
Place pump in operation
Check for leaks
Clean filter
Clean strainer
Repair or replace wires
Replace switch
Call serviceperson
Turn switch to "ON"

Pump not running
Pump air locked
Filter dirty
Pump strainer clogged
Defective wiring or connection
Defective pressure switch
Defective gas controls
On-Off switch in "OFF" position
Heater Short Cycling (Rapid On and Off Operation)

Insufficient water flow
Clean filter and pump strainer
Defective wiring
Repair or replace wiring
Defective flow valve or out of adjustment
Call serviceperson
Defective hi-limit and/or thermostat
Call serviceperson
Heater Makes Knocking Noises,
Make sure all valves on system are open
Heater operating after pump has shut off
Heater exchanger scaled

Rev. A 1-2-02

Shut off gas supply and call serviceperson
Shut off gas supply and call serviceperson

P/N 472032

MINIMAX NT STANDARD HEATER - (Dual Voltage)
1
2
3
4

6
7

8
9

13
14

10
15
11
16

17
24

19
30

20
21

29
22

31
33

38
35
39

40
41

P/N 472032

46 45

Rev. A 1-2-02

MiniMax NT Standard Dual Voltage Replacement Parts
ITEM
1
2
3
4
5
6
7
8
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
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
NA

DESCRIPTION
Exhaust Grill
Gasket, Exhaust Grill
Top Cover
Exhaust Assy.
Shut-off Safety Switch, Exhaust
Blower
Gasket, Blower
Flue Collector Assy.
Return Manifold Assy. Non-ASME
Bolt, Heat Exchanger, Non-ASME
W asher, Heat Exchanger
Fire box Assy.
Heat Exchanger Assy. Non-ASME
Baffle, Heat Exchanger
Thermistor Probe
Hi-Limit Thermostat-115° F.
Hi-Limit Thermostat-150° F.
W ater Pressure Switch
Main Manifold Assy. Non-ASME
Adapter, Bulkhead Ring
Adapter, Bulkhead, 2 in.
Gasket, Fin Tube, Seal
Flow Valve Assy.
Bracket, Gas Valve
Orifice, Natural Gas, 0-2000 Ft.
Orifice, Propane, 0-2000 Ft.
Gas Valve-Natural Gas
Gas Valve-Propane
Burner Tray Assy. Natural Gas
Burner Tray Assy. Propane
Igniter
Gas Manifold Assy. Natural Gas
Gas Manifold Assy. Propane
Burner Only
Burner with Bracket
Flame Sensor
Jacket, Upper Panel, Left
Jacket Corner
Jacket Divider
Jacket, Lower Panel, Left
Base
Jacket Back
Bracket, Jacket Side
Jacket, Upper Panel, Right
Jacket, Upper Subplate, Right
Jacket, Lower Panel, Right
Base Heat Shield
Control Box Assy.
Air Pressure Switch
Module, Ignition Control
Temperature Controller
Right Door Assy.
Left Door Assy.
Bracket, Front Burner Tray
Shield, Front Burner Tray
Thermal Cut-off (Not Shown)

QTY.
1
1
1
1
1
1
1
1
1
16
16
1
1
8 / 16(200/250/300/400)
1
1
1
1
1
2
2
18
1
1

200

471885
472030
471938
472008

471904
471910
471642

4 / 5 / 6 / 8(200/250/300/400)
1
1

472042
471907

1
1
2 / 3 / 4 / 6(200/250/300/400)
2
1
1
4
1
1
1
1
2
1
2
1
1
1
1
1
1
1
1
1
1
1

472023
472027

471827
471829
471861

471831
471747

471900
471891
471821

250
300
400
471592
471701
471692 471886 471591
472030
472040
471714
471883
471884
471610
472007 472006 472005
471991
471622
072184
471835 471922 471821
471785 471928 471838
471641 471896 471640
471566
471587
471694
471672
471993
274440
471441
070951
471750
471990
073727
073728
471601
471671
472037 472033 472028
471913 471925 471931
471602
472022 472021 472020
472026 472025 472024
070230
471970
471603
471575
471581
471651 471826 471580
471647
471645 471828 471573
471669 471874 471574
471768
471576
471767
471577
471646 471830 471579
472015
471743 471897 471569
471893
471565
471985
471659 471918 471726
471656 471890 471630
471655 471805 471631
075173

Note: Some parts are not listed in above table, please contact our Customer Service Department for details.
Rev. A 1-2-02

P/N 472032

40
32

MiniMax NT Standard Heaters
Limited Warranty
Your MiniMax NT Standard pool heater is another quality product from Pentair Pool
Products, Inc. and is backed by the following warranty.
1. The following parts are warranted for 5 years from date of purchase:
The MiniMax NT Standard cabinet and combustion chamber, the main burners and
burner manifold, the inlet/outlet header and the return header. This warranty does not
cover rusting or corrosion on cabinets or burners that does not affect the heater's
operation.
2. The following parts are covered for 2 years from date of purchase:
The automatic flow control valve, all controls, heat exchanger, pilot generator and the
pilot assembly.
This warranty only applies to the original purchaser.
3. This warranty shall not apply to any units or parts which have been subject to accident,
negligence, alteration, abuse, misapplication or misuse.
The above warranty applies only if the heater is installed and operated in complete
compliance with the installation and operation manual provided with each unit. Copies of
this manual are available by writing to Pentair Pool Products, Inc., at the address below.
Pentair Pool Products, Inc. assumes no liability except for the repair or replacements of
parts as specified above. Ship defective parts or equipment along with serial number and
purchase date, transportation prepaid to the address below. Purchaser shall be responsible
for freight charges for return of merchandise to purchaser. Some states do not allow
exclusion or limitation of incidental or consequential damages so the above may not apply
to you.
This warranty gives you specific legal rights, and you may also have other rights which
vary from state to state.
HEATER SERIAL NUMBER

(Please Fill In)
Pentair Pool Products, Inc.
1620 Hawkins Ave., Sanford, NC 27330 • (919) 774-4151
10951 W. Los Angeles Ave., Moorpark, CA 93021 • (805) 523-2400

P/N 472032

Rev. A 1-2-02

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