Carrier Single Package Rooftop 48Hc Users Manual 11SI

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48HC

Single Package Rooftop
Gas Heating/Electric Cooling Unit
with Puronr (R --- 410A) Refrigerant
Sizes: 17, 20, 24, 28

Installation Instructions
NOTE: Read the entire instruction manual before starting
the installation

TABLE OF CONTENTS
SAFETY CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . 2

Units without Thru-- Base Connections . . . . . . . . . 22

INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Field Control Wiring . . . . . . . . . . . . . . . . . . . . . . . 22

Jobsite Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Step 1 - Plan for Unit Location . . . . . . . . . . . . . . . . . . 9
Roof Mount . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Step 2 - Plan for Sequence of Unit Installation . . . . . 10
Curb-- Mount Installation . . . . . . . . . . . . . . . . . . . . 10
Pad-- Mount Installation . . . . . . . . . . . . . . . . . . . . . 10
Frame-- Mount Installation . . . . . . . . . . . . . . . . . . . 10
Step 3 - Inspect Unit . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Step 4 - Provide Unit Support . . . . . . . . . . . . . . . . . . 10
Roof Curb Mount . . . . . . . . . . . . . . . . . . . . . . . . . 10
Slab Mount (Horizontal Units Only) . . . . . . . . . . 10
Alternate Unit Support
(In Lieu of Curb or Slab Mount) . . . . . . . . . . . . . 10
Step 5 - Field Fabricate Ductwork . . . . . . . . . . . . . . . 14
Step 6 - Rig and Place Unit . . . . . . . . . . . . . . . . . . . . 14
Positioning on Curb . . . . . . . . . . . . . . . . . . . . . . . 15
Step 7 - Horizontal Duct Connection . . . . . . . . . . . . 15
Step 8 - Install Outside Air Hood — Factory Option . . 15
Step 9 - Install Flue Hood and Combustion Air Hood . . 16
Step 10 - Install Gas Piping . . . . . . . . . . . . . . . . . . . . 16
Gas Supply Line . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Factory-- Option Thru-- Base Connections . . . . . . . 18
Step 11 - Install External Condensate Trap and Line . . 19
Step 12 - Make Electrical Connections . . . . . . . . . . . 19
Field Power Supply . . . . . . . . . . . . . . . . . . . . . . . . 19
Units without Factory-- Installed Disconnect . . . . 20
Units with Factory-- Installed Disconnect . . . . . . . 20
All Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Convenience Outlets . . . . . . . . . . . . . . . . . . . . . . . 20
Factory-- Option Thru-- Base Connections . . . . . . 22

Thermostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Unit without Thru-- Base Conversion Kit . . . . . . . 22
Heat Anticipator Settings . . . . . . . . . . . . . . . . . . . 23
Transformer Connection
for 208--v Power Supply . . . . . . . . . . . . . . . . . . . . . 23
Humidi-- MiZerR Control Connections . . . . . . . . . . 24
Humidi-- MiZer - Space RH Controller . . . . . . . . 24
PremierLinkt (Factory Option) . . . . . . . . . . . . . . . 26
Supply Air Temperature (SAT) Sensor . . . . . . . . . 29
Outdoor Air Temperature (OAT) Sensor . . . . . . . 29
EconoMi$er2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Field Connections . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Space Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Connect Thermostat . . . . . . . . . . . . . . . . . . . . . . . 31
Configure the Unit for Thermostat Mode . . . . . . 31
Economizer Controls . . . . . . . . . . . . . . . . . . . . . . . . 32
Indoor Air Quality (CO2) Sensor . . . . . . . . . . . . . 32
Outdoor Air Quality Sensor . . . . . . . . . . . . . . . . . 32
Space Relative Humidity Sensor or
Humidistat Connections . . . . . . . . . . . . . . . . . . . . 33
Smoke Detector/Fire Shutdown (FSD) . . . . . . . . . 34
Filter Status Switch . . . . . . . . . . . . . . . . . . . . . . . . 34
Supply Fan Status Switch . . . . . . . . . . . . . . . . . . . 34
Remote Occupied Switch . . . . . . . . . . . . . . . . . . . 34
Power Exhaust (output) . . . . . . . . . . . . . . . . . . . . . 34
CCN Communication Bus . . . . . . . . . . . . . . . . . . 35
RTU Open Control System . . . . . . . . . . . . . . . . . . . 36
Supply Air Temperature (SAT) Sensor . . . . . . . . . 39
Outdoor Air Temperature (OAT) Sensor . . . . . . . 39
EconoMi$er2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Field Connections . . . . . . . . . . . . . . . . . . . . . . . . . . 39

!

Space Temperature (SPT) Sensors . . . . . . . . . . . . 40
Indoor Air Quality (CO2) Sensor . . . . . . . . . . . . . 40

FIRE, EXPLOSION HAZARD
Failure to follow this warning could result in personal
injury or death.
Disconnect gas piping from unit when leak testing at
pressure greater than 0.5 psig (3450 Pa). Pressures
greater than 0.5 psig (3450 Pa) will cause gas valve
damage resulting in hazardous condition. If gas valve
is subjected to pressure greater than 0.5 psig (3450
Pa), it must be replaced before use. When pressure
testing field-- supplied gas piping at pressures of 0.5
psig (3450 Pa) or less, a unit connected to such piping
must be isolated by closing the manual gas valve.

Outdoor Air Quality Sensor . . . . . . . . . . . . . . . . . 41
Space Relative Humidity Sensor or Humidistat . . 41
Smoke Detector/Fire Shutdown (FSD) . . . . . . . . . 42
Connecting Discrete Inputs . . . . . . . . . . . . . . . . . . 42
Communication Wiring - Protocols . . . . . . . . . . . . 43
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Local Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
RTU Open Troubleshooting . . . . . . . . . . . . . . . . . 44
Outdoor Air Enthalpy Control . . . . . . . . . . . . . . . . . 45
Differential Enthalpy Control . . . . . . . . . . . . . . . . 45
48HC

WARNING

!

Smoke Detectors . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Return Air Sensor Tube Installation . . . . . . . . . . . 46

WARNING

ELECTRICAL SHOCK HAZARD
Failure to follow this warning could cause personal
injury or death.
Before performing service or maintenance operations
on unit, always turn off main power switch to unit and
install lock(s) and lockout tag(s). Unit may have more
than one power switch.

Smoke Detector Test Magnet . . . . . . . . . . . . . . . . 47
Additional Application Data . . . . . . . . . . . . . . . . . 47
Step 13 - Adjust Factory-- Installed Options . . . . . . . . 50
Step 14 - Install Accessories . . . . . . . . . . . . . . . . . . . 50

SAFETY CONSIDERATIONS

!

Improper installation, adjustment, alteration, service,
maintenance, or use can cause explosion, fire, electrical
shock or other conditions which may cause personal injury
or property damage. Consult a qualified installer, service
agency, or your distributor or branch for information or
assistance. The qualified installer or agency must use
factory--authorized kits or accessories when modifying this
product. Refer to the individual instructions packaged with
the kits or accessories when installing.

WARNING

UNIT OPERATION AND SAFETY HAZARD
Failure to follow this warning could cause personal
injury, death and/or equipment damage.
Puronr (R-- 410A) refrigerant systems operate at
higher pressures than standard R-- 22 systems. Do not
use R-- 22 service equipment or components on Puron
refrigerant equipment.

Follow all safety codes. Wear safety glasses and work
gloves. Use quenching cloths for brazing operations and
have a fire extinguisher available. Read these instructions
thoroughly and follow all warnings or cautions attached to
the unit. Consult local building codes and appropriate
national electrical codes (in USA, ANSI/NFPA70,
National Electrical Code (NEC); in Canada, CSA C22.1)
for special requirements.

!

WARNING

PERSONAL INJURY AND ENVIRONMENTAL
HAZARD
Failure to follow this warning could cause personal
injury or death.
Relieve pressure and recover all refrigerant before
system repair or final unit disposal.
Ware safety glasses and gloves when handling
refrigerants. Keep torches and other ignition sources
away from refrigerants and oils.

It is important to recognize safety information. This is the
. When you see this symbol on the
safety-- alert symbol
unit and in instructions or manuals, be alert to the
potential for personal injury.
Understand the signal words DANGER, WARNING,
CAUTION, and NOTE. These words are used with the
safety-- alert symbol. DANGER identifies the most serious
hazards which will result in severe personal injury or
death. WARNING signifies hazards which could result in
personal injury or death. CAUTION is used to identify
unsafe practices, which may result in minor personal
injury or product and property damage. NOTE is used to
highlight suggestions which will result in enhanced
installation, reliability, or operation.

!

CAUTION

CUT HAZARD
Failure to follow this caution may result in personal
injury.
Sheet metal parts may have sharp edges or burrs. Use
care and wear appropriate protective clothing, safety
glasses and gloves when handling parts and servicing
air conditioning equipment.
2

48HC
Fig. 1 - Unit Dimensional Drawing – 17 Size Unit
3

C10896

48HC

Fig. 1 - Unit Dimensional Drawing – 17 Size Unit (cont.)

4

C10897

48HC
Fig. 2 - Unit Dimensional Drawing – 20 and 24 Size Units

5

C10892

48HC

Fig. 2 - Unit Dimensional Drawing – 20 and 24 Size Units (cont.)

6

C10893

48HC
Fig. 3 - Unit Dimensional Drawing – 28 Size Unit

7

C10900

48HC

Fig. 3 - Unit Dimensional Drawing – 28 Size Unit (cont.)

8

C10901

INSTALLATION
Jobsite Survey

Be sure that the unit is installed such that snow will not
block the combustion air intake or flute outlet.

1. Consult local building codes and the NEC (National
Electrical Code) ANSI/NFPA 70 for special installation requirements.
2. Determine unit location (from project plans) or select
unit location.
3. Check for possible overhead obstructions which may
interfere with unit lifting or rigging.

Step 1 — Plan for Unit Location
Select a location for the unit and its support system (curb
or other) that provides for the minimum clearances
required for safety. This includes the clearance to
combustible surfaces, unit performance and service access
below, around and above unit as specified in unit
drawings. See Fig. 4.
NOTE: Consider also the effect of adjacent units.

Do not install unit in an indoor location. Do not locate air
inlets near exhaust vents or other sources of contaminated
air. For proper unit operation, adequate combustion and
ventilation air must be provided in accordance with
Section 5.3 (Air for Combustion and Ventilation) of the
National Fuel Gas Code, ANSI Z223.1 (American
National Standards Institute) and NFPA (National Fire
Protection Association) 54 TIA-- - 54-- - 84-- - 1. In Canada,
installation must be in accordance with the CAN1-- - B149
installation codes for gas burning appliances.
Although unit is weatherproof, avoid locations that permit
water from higher level runoff and overhangs to fall onto
the unit.
Locate mechanical draft system flue assembly at least 4 ft
(1.2 m) from any opening through which combustion
products could enter the building, and at least 4 ft (1.2 m)
from any adjacent building (or per local code). Locate the
flue assembly at least 10 ft (3.05 m) from an adjacent
unit’s fresh air intake hood if within 3 ft (0.91 m) of same
elevation (or per local code). When unit is located
adjacent to public walkways, flue assembly must be at
least 7 ft (2.1 m) above grade.

96” (2438)

36” (914)
42” (1067)

42” (1067)

Unit may be installed directly on wood flooring or on Class
A, B, or C roof--covering material when roof curb is used.

Select a unit mounting system that provides adequate
height to allow installation of condensate trap per
requirements. Refer to Step 11 — Install External
Condensate Trap and Line – for required trap dimensions.

36” (914)

Roof Mount —
C10638

Fig. 4 - Service Clearance Dimensional Drawing

Check building codes for weight distribution
requirements. Unit operating weight is shown in Table 1.

Table 1 – Operating Weights
48HC**

UNIT LB (KG)
17

20

24

28

Base Unit

1892 (858)

2102 (954)

2247 (1019)

2292 (1040)

Economizer

245 (111)

245 (111)

245 (111)

245 (111)

32 (15)

32 (15)

32 (15)

32 (15)

83 (38)

83 (38)

88 (40)

92 (42)

14--- in/356 mm

273 (124)

273 (124)

273 (124)

273 (124)

24--- in/610 mm

350 (159)

350 (159)

350 (159)

350 (159)

Powered Outlet
Humidi--- MiZerR System
Curb

9

48HC

Complete the following checks before installation.

Step 2 — Plan for Sequence of Unit Installation

48HC

The support method used for this unit will dictate different
sequences for the steps of unit installation. For example, on
curb--mounted units, some accessories must be installed on
the unit before the unit is placed on the curb. Review the
following for recommended sequences for installation steps.
Curb-- mounted installation —
Install curb
Install field-- fabricated ductwork inside curb
Install thru-- base service connection fittings (affects
curb and unit)
Rig and place unit
Remove top skid
Install outside air hood
Install smoke detector tube
Install combustion air hood
Install flue hood
Install gas piping
Install condensate line trap and piping
Make electrical connections
Install other accessories
Pad-- mounted installation —
Prepare pad and unit supports
Rig and place unit
Remove duct covers and top skid
Install smoke detector return air sensor tube
Install field-- fabricated ductwork at unit duct openings
Install outside air hood
Install combustion air hood
Install flue hood
Install gas piping
Install condensate line trap and piping
Make electrical connections
Install other accessories
Frame-- mounted installation —
Frame-- mounted applications generally follow the
sequence for a curb installation. Adapt as required to
suit specific installation plan.

Step 3 — Inspect unit
Inspect unit for transportation damage. File any claim
with transportation agency.
Confirm before installation of unit that voltage, amperage
and circuit protection requirements listed on unit data
plate agree with power supply provided.
Locate the carton containing the outside air hood parts; see
Figs. 5 and 12. Do not remove carton until unit has been
rigged and located in final position.

Step 4 — Provide Unit Support
Roof Curb Mount —

NOTE: The gasketing of the unit to the roof curb is critical
for a watertight seal. Install gasket supplied with the roof
curb as shown in Figs. 6, 7 and 8. Improperly applied gasket
can also result in air leaks and poor unit performance.
Curb should be level. This is necessary for unit drain to
function properly. Unit leveling tolerances are show in
Fig. 9. Refer to Accessory Roof Curb Installation
Instructions for additional information as required.
Install insulation, cant strips, roofing felt, and counter
flashing as shown. Ductwork must be attached to curb and
not to the unit. Thru-- the-- base power connection must be
installed before the unit is set on the roof curb. If
field-- installed thru-- the-- roof curb gas connections are
desired remove knockout in basepan located in the gas
section, see Fig. 5 for location. Gas connections and
power connections to the unit must be field installed after
the unit is installed on the roof curb.
If electric and control wiring is to be routed through the
basepan, remove knockouts in basepan located in control
box area of access panel; see Fig. 1, 2, or 3 for basepan
knockout locations for location. Attach the service
connections to the basepan.
Hood Carton Location
(rear access panel)

Control Box
Access Panel

Filter and
Indoor Coil
Access Panel
Indoor Blower
Access Panel
Gas Heat
Access Panel

Compressor
(each side)
C11154

Fig. 5 - Typical Access Panel and Compressor Locations
Slab Mount (Horizontal Units Only) —

Provide a level concrete slab that extends a minimum of
6–in. (150 mm) beyond unit cabinet. Install a gravel apron
in front of condenser coil air inlet to prevent grass and
foliage from obstructing airflow.
NOTE: Horizontal units may be installed on a roof curb
if required.
Alternate Unit Support (In Lieu of Curb or Slab
Mount) —
A non-- combustible sleeper rail can be used in the unit
curb support area. If sleeper rails cannot be used, support
the long sides of the unit with a minimum of 4 equally
spaced 4-- in. x 4-- in. (102 mm x 102 mm) pads on each
side. Locate pads so that they support the rails. Make sure
to avoid the fork openings.

Accessory roof curb details and dimensions are shown in
Figs. 6, 7 and 8. Assemble and install accessory roof curb
in accordance with instructions shipped with the curb.
10

48HC
Fig. 6 - Roof Curb Details – 17 Size Unit

11

C10954

48HC

Fig. 7 - Roof Curb Details – 20 and 24 Size Units

12

C10955

48HC
Fig. 8 - Roof Curb Details – 28 Size Unit

13

C10956

A minimum clearance is not required around ductwork.

CAUTION

!
C

PROPERTY DAMAGE HAZARD
Failure to follow this caution may result in damage
to roofing materials.
Membrane roofs can be cut by sharp sheet metal
edges. Be careful when placing any sheet metal parts
on such roof.

MAXIMUM ALLOWABLE
DIFFERENCE IN. (MM)

A
B

A-B
0.25” (6)

B-C
0.5” (12)

A-C
0.5” (12)
C10628

Fig. 9 - Unit Leveling Tolerances

Step 6 — Rig and Place Unit

48HC

Step 5 — Field Fabricate Ductwork
Cabinet return-air static pressure (a negative condition)
shall not exceed 0.5 in. wg (87 Pa) with economizer or
without economizer.
For vertical ducted applications, secure all ducts to roof curb
and building structure. Do not connect ductwork to unit.
Fabricate supply ductwork so that the cross sectional
dimensions are equal to or greater than the unit supply
duct opening dimensions for the first 18 in. (458 mm) of
duct length from the unit basepan.

Keep unit upright and do not drop. Spreader bars are not
required if top crating is left on unit. Rollers may be used
to move unit across a roof. Level by using unit frame as a
reference. See Table 1 (on page 9) and Fig. 10 for
additional information.
Lifting holes are provided in base rails as shown in
Fig. 10. Refer to rigging instructions on unit.

CAUTION

!

Ducts passing through unconditioned spaces must be
insulated and covered with a vapor barrier.

UNIT DAMAGE HAZARD
Failure to follow this caution may result in
equipment damage.
All panels must be in place when rigging. Unit is not
designed for handling by fork truck when packaging
is removed.

If a plenum return is used on a vertical unit, the return
should be ducted through the roof deck to comply with
applicable fire codes.

Before setting the unit onto the curb, recheck gasketing on
curb.

Insulate and weatherproof all external ductwork, joints,
and roof openings with counter flashing and mastic in
accordance with applicable codes.

PLACE ALL SEAL STRIP
IN PLACE BEFORE PLACING
UNIT ON ROOF CURB.

"914-1371"
(36"-54")

DETAIL A

"B"
SEE DETAIL A

DUCT END

"C"

"A"

C09107

UNIT

NOTES:

DIMENSIONS

MAX WEIGHT

A

B

C

LB

KG

IN

MM

IN

MM

IN

MM

48HC**17

2339

1061

127.8

3249

58.7

1491

52.3

1328

48HC**20

2549

1156

141.5

3595

71.5

1816

52.3

1328

48HC**24

2699

1224

141.5

3595

71.5

1816

60.3

1532

48HC**28

2748

1246

157.8

4007

80.3

2040

60.3

1532

1. Dimensions in ( ) are inches.
2. Hook rigging shackles through holes in base rail, as shown in detail “A.” Holes in base rails are centered around the unit center of
gravity. Use wooden top to prevent rigging straps from damaging unit.

Fig. 10 - Rigging Details
14

Position unit on roof curb so that the following clearances
are maintained: 1/4 in. (6 mm) clearance between the roof
curb and the base rail inside the right and left, 1/2 in.
(12 mm) clearance between the roof curb and the base rail
inside the front and back. This will result in the distance
between the roof curb and the base rail inside on the
condenser end of the unit being approximately equal to
Details A and B in Figs. 6, 7 and 8.
Do not attempt to slide unit on curb after unit is set. Doing
so will result in damage to the roof curb seal.
Although unit is weatherproof, guard against water from
higher level runoff and overhangs.
Flue vent discharge must have a minimum horizontal
clearance of 48 in. (1220 mm) from electric and gas meters,
gas regulators, and gas relief equipment. Minimum distance
between unit and other electrically live parts is 48 inches
(1220 mm).
Flue gas can deteriorate building materials. Orient unit such
that flue gas will not affect building materials. Locate
mechanical draft system flue assembly at least 48 in. (1220
mm) from an adjacent building or combustible material.

Field--supplied (3/4- inch) flanges should be attached to
horizontal duct openings (see Fig. 11) and all ductwork
should be secured to the flanges. Insulate and weatherproof
all external ductwork, joints, and roof or building openings
with counter flashing and mastic in accordance with
applicable codes.

Step 8 — Install Outside Air Hood — Factory
Option
The outside air hood for factory-- option economizer and
two-- position damper is shipped in knock-- down form and
requires field assembly. The panel for the hood top is
shipped on the end of the unit (see Fig. 12). The
remaining parts for the hood assembly (including side
panels, filters and tracks) are shipped in a carton that is
secured to the rear of the blower assembly. Access the
carton location through rear panel (see Fig. 13).
48HC

Positioning on Curb —

Hood Top
Shipping
Position

After unit is in position, remove rigging skids and
shipping materials.
Fig. 12 - Hood Top – Shipping Position

Step 7 — Horizontal Duct Connection
Refer to Figs. 1, 2 and 3 for locations and sizes of the
horizontal duct connections. Note that there are two different
return air duct connection locations – one for unit without an
economizer (on back side of unit) and a different one for
unit equipped with an economizer (on left end, under the
economizer hood). The supply air duct connection is on the
back side. See Fig. 11 for top view depicting typical
horizontal duct arrangements.

C09134

To remove the hood parts package:
1. Remove the back blower access panel.
2. Locate and cut the strap, being careful to not damage
any wiring.
3. Carefully lift the hood package carton through the
back blower access opening.
See Fig. 14 for identification of the various parts of the
hood assembly.

Hood
Package

Horizontal
Supply Air
Return Air Duct
without
Economizer

Return Air Duct
with Economizer

C10626

Supply

Return without
Economizer

Return with
Economizer

Location

Back

Back

Left end

Height --- In. (mm)

157/8 (402)

493/8 (1253)

183/8 (467)

Width --- in. (mm)

293/4 (756)

233/8 (593)

615/8 (1564)

Fig. 13 - Hood Package – Shipping Location

Fig. 11 - Horizontal Duct Opening Dimensions
15

C09133

To assemble the outside air hood:
1. Remove hood top panel from shipping position on
unit end.
2. Install four angles to the upper end panel using the
screws provided.
3. Apply seal strip to mating flanges on the side plates
of the hood (see Fig. 14).
Apply Seal Strips
to the back of
these surfaces

3

Apply Seal Strip
to the front of
this flange

Apply Seal Strips
to the back of
these flanges

The combustion air hood is attached to the back of the
burner access panel. Remove the two screws securing the
hood to the back of the burner access panel. Using the two
screws, re-- attach the hood to the front of the burner
access panel as shown in Fig. 16.

Apply Seal Strip
to the front of
this flange
7

7
2

2
4

4
5

4
4

6

48HC

1
Seal Strips

5

Apply Seal Strip
to the back of
this flange

6
Item #
1
2
3
4
5
6
7

Description
Qty
Angles
4
Side Plates
2
Hood
1
Outdoor Air Screens 4
Side Filter Supports 2
Side Drip Angles
2
Top Diverters
2

Combustion
Air Hood

Flue Hood
C10744

Fig. 16 - Flue Hood and Combustion Air Hood Details
C09079

Fig. 14 - Hood Part Identification and Seal Strip
Application Areas

4. Secure side plates to panel using the screws provided.
5. Apply seal strip to mating flange of the hood (see
Fig. 14).
6. Secure top flange using screws provided in kit.
7. Install outdoor air screens by sliding them into the
channel formed by the four angles installed in step 2.
Make sure that the screens extend across the entire
length of the hood.
8. Install side filter supports using the screws provided.
9. Install side drip angles using the screws provided.
10. Run a continuous length of seal strip across the hood
covering the engagement holes in the lower hood.
11. Install top diverter using the screws provided.
12. On units with barometric relief, remove screws at bottom of relief damper. Do not discard damper door.

Step 10 — Install Gas Piping
Installation of the gas piping must be in accordance with
local building codes and with applicable national codes.
In U.S.A., refer to NFPA 54/ANSI Z223.1 National Fuel
Gas Code (NFGC). In Canada, installation must be
accordance with the CAN/CSA B149.1 and CAN/CSA
B149.2 installation codes for gas burning appliances.
This unit is factory equipped for use with Natural Gas fuel
at elevations up to 2000 ft (610 m) above sea level. Unit
may be field converted for operation at elevations above
2000 ft (610 m) and/or for use with liquefied petroleum
fuel. See accessory kit installation instructions regarding
these accessories.
NOTE: Furnace gas input rate on rating plate is for
installation up to 2000 ft (610 m) above sea level. In
U.S.A. the input rating for altitudes above 2000 ft (610 m)
must be derated by 4% for each 1000 ft (305 m) above sea
level. In Canada the input rating must be derated by 10%
for altitudes of 2000 ft (610 m) to 4500 ft (1372 m) above
sea level.
For natural gas applications, gas pressure at unit gas
connection must not be less than 5 in. wg (1246 Pa) or
greater than 13 in. wg (3240 Pa) while the unit is
operating. For liquified petroleum applications, the gas
pressure must not be less than 11 in. wg (2740 Pa) or
greater than 13 in. wg (3240 Pa) at the unit connection.

Fig. 15 - Hood Assembly – Completed

C09090

Step 9 — Install Flue Hood and Combustion Air
Hood
The flue hood is shipped screwed to the fan deck inside
the burner compartment. Remove the burner access panel
and then remove the flue hood from its shipping location.
Using the screws provided, install flue hood in the
location shown in Fig. 16.

Gas Supply Line —
The gas supply pipe enters the unit adjacent to the burner
access panel on the front side of the unit, through the
grommeted hole. The gas connection to the unit is made
to the 3/4 in. FPT gas inlet port on the unit gas valve.
Table 2 lists typical 3/4 inch NPT (National Pipe Thread)
field supplied pipe fittings required for Thru-- Base gas
supply, starting from the unit gas valve (see Fig. 17).

16

Table 2 – Typical 3/4- in NPT Field Supplied Piping Parts

4

5

3

6

Item

Qty

CPN

Description

1

1

CA15RA201

90 Deg Street Elbow

2

1

CA01CA226

5 Inch Long Nipple

3

1

CA85RA201

Ground --- Joint Union

4

1

CA01CA218

3 Inch Long Nipple

5

1

CA05RA201

90 Deg Elbow

6

1

CA01CA250

12 Inch Long Nipple

7

1

CA05RA201

90 Deg Elbow

8

1

CA01CA218

3 Inch Long Nipple

9

1

CA20RA201

TEE

10

1

CA01CN222

4 Inch Long Nipple (Sediment Trap)

11

1

CA38RA201

Cap

12

1

CA01CA220

3 1/2 Inch Long Nipple

13

1

GB30

NIBCOR Ball Valve

14

1

CA01CA238

8 Inch Long Nipple

15

1

CA05RA201

90 Deg Elbow

2

1

7
15
8

9
10
11
12
13

C10999

Fig. 17 - Gas Supply Line Piping with Thru-- Base

Pipe gas supply into 90 degree elbow item 15 (see Table 2)
through the hole in the unit basepan.

4

5

3

6

For typical 3/4 inch NPT field supplied fittings required
for NON Thru-- Base gas supply starting from the unit gas
valve, omit items 14 and 15 from Table 2 and pipe gas
supply into TEE. See Fig. 18.

2

1

7

8
9

Table 3 – Natural Gas Supply Line Pressure Ranges
UNIT MODEL
48HC**

!

UNIT SIZE

MIN

MAX

17, 20, 24, 28

5.0 in. wg
(1246 Pa)

13.0 in. wg
(3240 Pa)

12

10

13
11

CAUTION

EQUIPMENT DAMAGE HAZARD
Failure to follow this caution may result in damage
to equipment.
When connecting the gas line to the unit gas valve,
the installer MUST use a backup wrench to prevent
damage to the valve.
Install a gas supply line that runs to the unit heating
section. Refer to the NFPA 54/NFGC or equivalent code
for gas pipe sizing data. Do not use a pipe smaller than the
size specified. Size the gas supply line to allow for a
maximum pressure drop of 0.5-- in wg (124 Pa) between
gas regulator source and unit gas valve connection when
unit is operating at high-- fire flow rate.

Fig. 18 - Gas Supply Line Piping

C101006

X
9” MINIMUM CLEARANCE
FOR PANEL REMOVAL

GAS
REGULATOR*
MANUAL GAS
SHUTOFF VALVE*

BASE UNIT

FROM
GAS
METER

48” MINIMUM
DRIP LEG
PER NFGC*
BASE RAIL
FIELDFABRICATED
SUPPORT*

ROOF
CURB

The gas supply line can approach the unit in two ways:
horizontally from outside the unit (across the roof), or
through unit basepan. Observe clearance to gas line
components per Fig. 19.

LEGEND
NFGC – National Fuel Gas Code
*Field supplied.
NOTE: Follow all local codes.

STEEL PIPE
NOMINAL DIAMETER
(in.)

SPACING OF SUPPORTS
X DIMENSION
(ft)

1/
2
3/ or 1
4
1
1 /4 or larger

6
8
10

Fig. 19 - Gas Piping Guide
17

C11121

48HC

14

Factory-- Option Thru-- Base Connections —

48HC

Electrical Connections: Knockouts are located in the
control box area. Remove the appropriate size knockout
for high voltage connection. Use the field supplied
connector depending on wiring or conduit being utilized.
Remove the 7/8 - in (22mm) knockout and appropriate
connector for low voltage wiring. If non-- unit powered
convenience outlet is being utilized, remove the 7/8 - in
(22mm) knockout and utilize appropriate connector for
115 volt line. See “Step 12 — Making Electrical
Connections” for details.
Gas Connections: Remove the knockout in the base pan
and route 3/4 - in. gas line up through the opening. Install
an elbow and route gas line through opening in panel after
first removing plastic bushing. Install a gas shut off
followed by a drip leg and ground-- joint union. Route gas
line into gas section through the grommet (Part #:
KA56SL112) at the gas inlet and into the gas valve. See
Fig. 17 and Table 2. If a regulator is installed, it must be
located 4 feet (1.22 meters) from the flue outlet.

NOTE: Pressure test the gas supply system after the gas
supply piping is connected to the gas valve. The supply
piping must be disconnected from the gas valve during the
testing of the piping systems when test pressure is in
excess of 0.5 psig (3450 Pa). Pressure test the gas supply
piping system at pressures equal to or less than 0.5 psig
(3450 Pa). The unit heating section must be isolated from
the gas piping system by closing the external main manual
shutoff valve and slightly opening the ground-- joint union.
Check for gas leaks at the field--installed and
factory--installed gas lines after all piping connections have
been completed. Use soap--and--water solution (or method
specified by local codes and/or regulations).

!

FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in personal
injury, death and/or property damage.
S Connect gas pipe to unit using a backup wrench to
avoid damaging gas controls.
S Never purge a gas line into a combustion chamber.
S Never test for gas leaks with an open flame. Use a
commercially available soap solution made
specifically for the detection of leaks to check all
connections.
S Use proper length of pipe to avoid stress on gas
control manifold.

Some municipal codes require that the manual shutoff
valve be located upstream of the sediment trap. See
Fig. 18 for typical piping arrangements for gas piping that
has been routed through the sidewall of the base pan.
When installing the gas supply line, observe local codes
pertaining to gas pipe installations. Refer to the NFPA
54/ANSI Z223.1 NFGC latest edition (in Canada, CAN/CSA
B149.1). In the absence of local building codes, adhere to
the following pertinent recommendations:
1. Avoid low spots in long runs of pipe. Grade all pipe
1/ - in. in every 15 ft (7 mm in every 5 m) to prevent
4
traps. Grade all horizontal runs downward to risers.
Use risers to connect to heating section and to meter.
2. Protect all segments of piping system against physical
and thermal damage. Support all piping with appropriate straps, hangers, etc. Use a minimum of one
hanger every 6 ft (1.8 m). For pipe sizes larger than
1/ - in., follow recommendations of national codes.
2
3. Apply joint compound (pipe dope) sparingly and only to
male threads of joint when making pipe connections.
Use only pipe dope that is resistant to action of liquefied petroleum gases as specified by local and/or national codes. If using PTFE (Teflon) tape, ensure the material is Double Density type and is labeled for use on gas
lines. Apply tape per manufacturer’s instructions.
4. Pressure-- test all gas piping in accordance with local
and national plumbing and gas codes before connecting piping to unit.

WARNING

NOTE: If orifice hole appears damaged or it is suspected to
have been redrilled, check orifice hole with a numbered drill
bit of correct size. Never redrill an orifice. A burr--free and
squarely aligned orifice hole is essential for proper flame
characteristics.

BURNER
ORIFICE

Fig. 20 - Orifice Hole

18

A93059

Step 12 — Make Electrical Connections

ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury or death.
Do not use gas piping as an electrical ground. Unit
cabinet must have an uninterrupted, unbroken electrical
ground to minimize the possibility of personal injury if
an electrical fault should occur. This ground may consist
of electrical wire connected to unit ground lug in control
compartment, or conduit approved for electrical ground
when installed in accordance with NEC (National
Electrical Code); ANSI/NFPA 70, latest edition (in
Canada, Canadian Electrical Code CSA [Canadian
Standards Association] C22.1), and local electrical
codes.
NOTE: Field-- supplied wiring shall conform with the
limitations of minimum 63_F (33_C) rise.

CONDENSATE
DRAIN
CONNECTION

Field Power Supply —

Fig. 21 - Condensate Drain Pan Connection

C10729

The piping for the condensate drain and external trap can
be completed after the unit is in place. Hand tighten
fittings to the drain pan fitting. Provide adequate support
for the drain line. Failure to do so can result in damage to
the drain pan. See Fig. 22.

MINIMUM PITCH
1” (25mm) PER
10’ (3m) OF LINE

WARNING

!

The unit has one 3/4-in. condensate drain connection on
the end of the condensate pan (see Fig. 21). See Figs. 1, 2
and 3, item “E”, in the view labeled “BACK
(HORIZONTAL DISCHARGE)” for the location of the
condensate drain connection.

If equipped with optional Powered Convenience Outlet:
The power source leads to the convenience outlet’s
transformer primary are not factory connected. Installer
must connect these leads according to required operation
of the convenience outlet. If an always-- energized
convenience outlet operation is desired, connect the
source leads to the line side of the unit-- mounted
disconnect. (Check with local codes to ensure this method
is acceptable in your area.) On a unit without a
unit-- mounted disconnect, connect the source leads to the
line side with unit field power leads. See Fig. 23.

BASE RAIL

BLK
OPEN
VENT

YEL

2˝ (51) MIN

BLU
LOAD
SIDE

TO ROOF
DRAIN

SEE NOTE

DRAIN PLUG

LINE
SIDE

ROOF
CURB

SEE
DETAIL A

NOTE: Trap should be deep enough to offset maximum unit static
difference. A 4” (102) trap is recommended
.

Fig. 22 - Condensate Drain Piping Details

L1

C08022

All units must have an external trap for condensate
drainage. Install a trap at least 4-in. (102 mm) deep and
protect against freeze-up. If drain line is installed
downstream from the external trap, pitch the line away
from the unit at 1-in. per 10 ft (25 mm in 3 m) of run. Do
not use a pipe size smaller than the unit connection
( 3/4 -in.).

L2
L3

DETAIL A
CONTROL BOX

Fig. 23 - Location of TB1

C11181

Field power wires are connected to the unit at line-- side
pressure lugs on the terminal block (see wiring diagram
label for control box component arrangement) or at
factory-- installed option non-- fused disconnect switch. Use
copper conductors only.
NOTE: Make field power connections directly to line
connection pressure lugs only.
19

48HC

Step 11 — Install External Condensate Trap and
Line

!

WARNING

!

CAUTION

UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage.
Operation on improper line voltage or excessive phase
imbalance constitutes abuse and may cause damage to
electrical components. Such operation would invalidate
any applicable Carrier warranty.

FIRE HAZARD
Failure to follow this warning could result in
intermittent operation or unsatisfactory performance.
Do not connect aluminum wire between disconnect
switch and air conditioning unit. Use only copper
wire. (See Fig. 24.)

Units Without Disconnect Option
ELECTRIC
DISCONNECT
SWITCH

TB1
11

12

13

48HC

COPPER
WIRE ONLY
ALUMINUM
WIRE

Fig. 24 - Disconnect Switch and Unit

Disconnect
per
NEC

A93033

L1

Units without Factory-- Installed Disconnect —
When installing units, provide a disconnect switch per
NEC (National Electrical Code) of adequate size.
Disconnect sizing data is provided on the unit informative
plate. Locate on unit cabinet or within sight of the unit per
national or local codes. Do not cover unit informative
plate if mounting the disconnect on the unit cabinet.

L2
L3
208/230-3-60
460-3-60
575-3-60

Units With Disconnect Option
Factory
Wiring

Units with Factory-- Installed Disconnect —
The factory-- installed option disconnect switch is located
in the main control box. The manual switch handle is
accessible on the corner post adjacent to the control box
access panel.

T1

All field wiring must comply with NEC and all local code
requirements.

Provide a ground-- fault and short-- circuit over-- current
protection device (fuse or breaker) per NEC Article 440
(or local codes). Refer to unit informative data plate for
MOCP (Maximum Over-- current Protection) device size.

T3

Optional
Disconnect
Switch

All Units -

Size wire based on MCA (Minimum Circuit Amps) on the
unit informative plate. See Fig. 25 for power wiring
connections to the unit power terminal block and equipment
ground. Maximum wire size is 2/0 AWG per pole.

T2

L1

L2

L3

L1

L2

L3

Fig. 25 - Power Wiring Connections

C101000

Convenience Outlets —

!

WARNING

ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal
injury or death.
Units with convenience outlet circuits may use
multiple disconnects. Check convenience outlet for
power status before opening unit for service. Locate
its disconnect switch, if appropriate, and open it.
Lock-- out and tag-- out this switch, if necessary.

Voltage to compressor terminals during operation must be
within voltage range indicated on unit nameplate. See
Table 11. On 3-- phase units, voltages between phases must
be balanced within 2% and the current within 10%. Use
the formula shown in the legend for Table 11 (see Note 2
on page 49) to determine the percent of voltage
imbalance.

20

Two types of convenience outlets are offered on 48HC
models: Non--unit powered and unit--powered. Both types
provide a 125--volt GFCI (ground--fault circuit--interrupter)
duplex receptacle rated at 15--A behind a hinged access
cover, located on the corner panel of the unit. See Fig. 26.
Control Box
Access Panel

Non-- unit powered type: This type requires the field
installation of a general-- purpose 125-- volt 15-- A circuit
powered from a source elsewhere in the building. Observe
national and local codes when selecting wire size, fuse or
breaker requirements and disconnect switch size and
location. Route 125-- v power supply conductors into the
bottom of the utility box containing the duplex receptacle.

Convenience
Outlet

Fig. 26 - Convenience Outlet Location

C10641

Installing Weatherproof Cover: A weatherproof
while-in-use cover for the factory-installed convenience
outlets is now required by UL standards. This cover cannot
be factory-mounted due to its depth; it must be installed at
unit installation. For shipment, the convenience outlet is
covered with a blank cover plate.

The primary leads to the convenience outlet transformer
are not factory-- connected. If local codes permit, the
transformer primary leads can be connected at the
line-- side terminals on the unit-- mounted non-- fused
disconnect switch; this will provide service power to the
unit when the unit disconnect switch is open. See Fig. 28.

The weatherproof cover kit is shipped in the unit’s control
box. The kit includes the hinged cover, a backing plate
and gasket.
DISCONNECT ALL POWER TO UNIT AND
CONVENIENCE OUTLET. LOCK--OUT AND TAG--OUT
ALL POWER.
Remove the blank cover plate at the convenience outlet;
discard the blank cover.
Loosen the two screws at the GFCI duplex outlet, until
approximately 1/2-in (13 mm) under screw heads are
exposed. Press the gasket over the screw heads. Slip the
backing plate over the screw heads at the keyhole slots
and align with the gasket; tighten the two screws until
snug (do not over-tighten).
Mount the weatherproof cover to the backing plate as
shown in Fig. 27. Remove two slot fillers in the bottom of
the cover to permit service tool cords to exit the cover.
Check for full closing and latching.
COVER – WHILE-IN-USE
WEATHERPROOF

RECEPTACLE
NOT SHOWN

C10730

UNIT
VOLTAGE

CONNECT
AS

PRIMARY
CONNECTIONS

TRANSFORMER
TERMINALS

208,
230

240

L1: RED +YEL
L2: BLU + GRA

H1 + H3
H2 + H4

460

480

L1: RED
Splice BLU + YEL
L2: GRA

H1
H2 + H3
H4

575

600

L1: RED
L2: GRA

H1
H2

Fig. 28 - Powered Convenience Outlet Wiring

BASE PLATE FOR
GFCI RECEPTACLE

Fig. 27 - Weatherproof Cover Installation

C09022

21

48HC

Unit-- powered type: A unit-- mounted transformer is
factory-- installed to stepdown the main power supply
voltage to the unit to 115-- v at the duplex receptacle. This
option also includes a manual switch with fuse, located in
a control box and mounted on a bracket behind the
convenience outlet; access is through the unit’s control
box access panel. See Fig. 26.

Electric
Disconnect
Switch

Field Control Wiring —

NOTICE/AVIS
Convenience Outlet Utilization
Maximum Intermittent Use 15 - Amps
Maximum Continuous Use 8 - Amps
Observe a 50% limit on the circuit
Loading above 8 - Amps

Utilisation de la prise utilitaire

Usage intermittent maximum 15 - Amps
Usage continu maximum 8 - Amps
Observez une limite de 50% sur le circuit
Chargement au-dessus de 8 - Amps 50HE501288

2.0

C10077

48HC

Fig. 29 - Convenience Outlet Utilization Notice

Test the GFCI receptacle by pressing the TEST button on
the face of the receptacle to trip and open the receptacle.
Check for proper grounding wires and power line phasing
if the GFCI receptacle does not trip as required. Press the
RESET button to clear the tripped condition.
Using unit-- mounted convenience outlets: Units with
unit-- mounded convenience outlet circuits will often
require that two disconnects be opened to de-- energize all
power to the unit. Treat all units as electrically energized
until the convenience outlet power is also checked and
de-- energization is confirmed. Observe National Electrical
Code Article 210, Branch Circuits, for use of convenience
outlets.
Factory-- Option Thru-- Base Connections —
All units are equipped with the ability to bring utilities
through the base.
Gas is brought up through an embossed area located in the
gas section behind the gas entrance post. Access is gained
through the gas access panel. A knock out must be
removed to accomplish this.
The electrical entrance is located in the control box area
and can be accessed through the control box access panel.
An embossed area is provided with three knock outs. High
voltage is brought through the multi knock out by
removing the appropriate size for the size of the fitting
required. A 7/8 - in. knock out is provided for low voltage.
An additional 7/8 - in. knock out is provided for a 115 volt
line which is used when the unit is equipped with the
non-- unit powered convenience outlet option.

The 48HC unit requires an external temperature control
device. This device can be a thermostat (field-- supplied)
or a PremierLink controller (available as factory-- installed
option or as field-- installed accessory, for use on a Carrier
Comfort Network or as a stand alone control) or the RTU
Open for Building Management Systems using non-- CCN
protocols (RTU Open is available as a factory-- installed
option only).
Thermostat —
Install a Carrier-- approved accessory 2-- stage thermostat
according to installation instructions included with the
accessory. Locate the thermostat accessory on a solid wall
in the conditioned space to sense average temperature in
accordance with the thermostat installation instructions.
If the thermostat contains a logic circuit requiring 24-- v
power, use a thermostat cable or equivalent single leads of
different colors with minimum of seven leads. If the
thermostat does not require a 24-- v source (no “C”
connection required), use a thermostat cable or equivalent
with minimum of six leads. Check the thermostat
installation instructions for additional features which
might require additional conductors in the cable.
For wire runs up to 50 ft. (15 m), use no. 18 AWG
(American Wire Gage) insulated wire (35_C minimum).
For 50 to 75 ft. (15 to 23 m), use no. 16 AWG insulated
wire (35_C minimum). For over 75 ft. (23 m), use no. 14
AWG insulated wire (35_C minimum). All wire sizes
larger than no. 18 AWG cannot be directly connected to
the thermostat and will require a junction box and splice
at the thermostat.
Unit without Thru-- Base Connection Kit —
Correctly rated low voltage wire can be routed through the
rubber grommet located on the corner post adjacent to the
control box access panel. Route wire through the grommet
and then route the wire behind the corner post utilizing the
factory provided wire ties secured to the control box. This
will insure separation of the field low voltage wire and the
high voltage circuit. Route the low voltage wire to the
central terminal board. See Fig. 30.

All required fittings are field supplied. Install fittings
when access to both top and bottom of the base pan is
available. See electrical and gas connections for routing
and connection information.
Units without Thru-- Base Connections —
1. Install liquid tight conduit between disconnect and
control box.
2. Pull correctly rated high voltage wires through the
conduit.
3. Install power lines to terminal connections as shown
in Fig. 25.

22

Central
Terminal
Board

Typical
Thermostat
Corrections

X

X

C

C

G

G

W2

W2

W2

W1

W1

W1

O/B/Y2

Y2

Y2

Y1

Y1

Y1

R

R

R

C
See
Caution

G

Rubber
Grommet

Corner
Post

Wire
Ties

48HC

(see Note)

T–STAT
Note: Typical multi-function marking. Follow manufacturer’s configuration
instructions to select Y2.
Field Wiring

!

CAUTION

Thru the Base
Connection

UNIT DAMAGE HAZARD
Failure to follow this caution may cause a short circuit.
Carefully check the connection of control coductor
for indoor fan control at terminal G. Connecting the
indoor fan lead to terminal C will cause a short circuit
condition which can cause component damage inside
the unit or at thermostat.
C10731

Fig. 30 - Typical Low-- Voltage Control Connections

NOTE: If utilizing the through the base connections,
route the low voltage wire through the wire ties to the
central terminal board.

Fig. 31 - Field Control Wiring Raceway

C10734

Heat Anticipator Settings —
Set heat anticipator settings at 0.14 amp for the first stage
and 0.14 amp for second-- stage heating.
Transformer Connection for 208-- v Power Supply —
All units except 208/230-v units are factory wired for the
voltage shown on the nameplate. If the 208/230-v unit is
to be connected to a 208-v power supply, the control
transformer must be rewired by moving the black wire
with the 1/4 -in. female spade connector from the 230-- v
connection and moving it to the 208-v 1/4 -in. male
terminal on the primary side of the transformer. Refer to
unit label diagram for additional information.

23

Humidi--MiZerR Control Connections

48HC

Humidi-- MiZer – Space RH Controller —
NOTE: The Humidi-- MiZer is a factory installed option.
The Humidi-- MiZer dehumidification system requires a
field-- supplied and - installed space relative humidity
control device. This device may be a separate humidistat
control (contact closes on rise in space RH above control
setpoint) or a combination thermostat-- humidistat control
device such as Carrier’s EDGER Pro Thermidistat with
isolated contact set for dehumidification control. The
humidistat is normally used in applications where a
temperature control is already provided (units with
PremierLinkt control).
To connect the Carrier humidistat (HL38MG029):
1. Route the humidistat 2-- conductor cable (field-- supplied) through the hole provided in the unit corner
post.
2. Feed wires through the raceway built into the corner
post (see Fig. 31) to the 24-- v barrier located on the
left side of the control box. The raceway provides the
UL-- required clearance between high-- voltage and
low-- voltage wiring.
3. Use wire nuts to connect humidistat cable to two
PINK leads in the low–voltage wiring as shown in
Fig. 34.
To connect the Thermidistat device (33CS2PPRH-- 01):
1. Route the Thermidistat multi-- conductor thermostat
cable (field-- supplied) through the hole provided in
the unit corner post.
2. Feed wires through the raceway built into the corner
post (see Fig. 31) to the 24-- v barrier located on the
left side of the control box. The raceway provides the
UL-- required clearance between high-- voltage and
low-- voltage wiring.
3. The Thermidistat has dry contacts at terminals D1
and D2 for dehumidification operation (see Fig. 35).
The dry contacts must be wired between CTB
terminal R and the PINK lead to the LTLO switch
with field-- supplied wire nuts. Refer to the installation
instructions included with the Carrier Edge
Thermidistat device (Form 33CS-- 65SI or latest) for
more information.

% RELATIVE HUMIDITY

C09295

Fig. 32 - Accessory Field-- Installed Humidistat

®

Fig. 33 - EDGE Pro Thermidistat

24

C09296

48HC
Fig. 34 - Typical Humidi-- MiZerR Adaptive Dehumidification System Humidistat Wiring

EDGE Pro THERMIDISTAT

C11139

Unit CTB
THERMOSTAT

X*

Rc
Rh
W1
G
Y2
C
O/W2/B
Y1

C
G
W2
W1
Y2
Y1

OAT
RRS
SRTN
HUM
D1
D2
V+
Vg

R
Humidi-MiZer™ FIOP

*Connection not required.

Fig. 35 - Typical Rooftop Unit with Humidi-- MiZer Adaptive Dehumidification System
with EDGE Pro Thermidistat Device
25

C09298

48HC

PremierLinkt (Factory--Option)

Fig. 36 - PremierLink Controller

C08199

The PremierLink controller (see Fig. 36) is compatible
with Carrier Comfort Networkr (CCN) devices. This
control is designed to allow users the access and ability to
change factory-- defined settings, thus expanding the
function of the standard unit control board. CCN service
access tools include System Pilott, Touch Pilott and
Service Tool. (Standard tier display tools Navigatort and
Scrolling Marquee are not suitable for use with latest
PremierLink controller (Version 2.x).)
The PremierLink control is factory--mounted in the 48HC
unit’s main control box to the right of the Central Terminal
Board (CTB) (see Fig. 37). Factory wiring is completed
through harnesses connected to the CTB thermostat. Field
connections are made at a 16-- pole terminal block (TB3)
located at the top of the unit control box in front of the
PremierLink controller. The factory--installed PremierLink
control includes the supply--air temperature (SAT) sensor.
The outdoor air temperature (OAT) sensor is included in the
FIOP/accessory EconoMi$ert2 package. (See page 45 for
accessory enthalpy controls.)
The PremierLink controller requires the use of
electronic thermostat or a CCN connection
broadcast to initiate its internal timeclock.
necessary for broadcast of time of day
(occupied/unoccupied).

a Carrier
for time
This is
functions

C10643

Fig. 37 - 48HC Control Box Component Locations

NOTE: PremierLink controller is shipped in Sensor
mode. To be used with a thermostat, the PremierLink
controller must be configured to Thermostat mode. Refer
to PremierLink Configuration instructions for Operating
Mode.

26

48HC
Fig. 38 - PremierLink Wiring Schematic

27

C11140

48HC

Fig. 39 - PremierLink Wiring Schematic with Humidi-- MiZerR

28

C11141

Supply Air Temperature (SAT) Sensor —

NOTE: The sensor must be mounted in the discharge
airstream downstream of the cooling coil and any heating
devices. Be sure the probe tip does not come in contact
with any of the unit’s heater surfaces.

On FIOP-- equipped 48HC unit, the unit is supplied with a
supply-- air temperature (SAT) sensor (33ZCSENSAT).
This sensor is a tubular probe type, approx 6-- inches (12.7
mm) in length. It is a nominal 10-- k ohm thermistor.

Outdoor Air Temperature (OAT) Sensor —
The OAT is factory-- mounted in the EconoMi$er2 (FIOP
or accessory). It is a nominal 10k ohm thermistor attached
to an eyelet mounting ring.

The SAT is factory-- wired. The SAT probe is mounted in
the fan deck (see Fig. 40). It can be removed or
remounted per local codes.. Drill or punch a 1/2-- in. hole
in the flange or duct. Use two field-- supplied, self-- drilling
screws to secure the sensor probe in a horizontal
orientation. Insure that the sensor wires do not contact the
hot surface of the heat exchanger.

EconoMi$er2 —

Outdoor air management functions can be enhanced with
field-- installation of these accessory control devices:
Enthalpy control (outdoor air or differential sensors)
Space CO2 sensor
Outdoor air CO2 sensor
SUPPLY AIR
TEMPERATURE
SENSOR

Refer to Table 4 for accessory part numbers.

ROOF
CURB
SUPPLY AIR

Field Connections

RETURN AIR

Fig. 40 - Mounting Location for Supply Air
Temperature (SAT) Sensor on 48HC Units

Field connections for accessory sensor and input devices
are made at the 16-- pole terminal block (TB3, see Fig. 38
and Fig. 39) located on the control box top shelf in front
of the PremierLink control. Some input devices also
require a 24-- vac signal source; connect at CTB terminal
R at “THERMOSTAT” connection strip for this signal
source. See connections figures on following pages for
field connection locations (and for continued connections
at the PremierLink board inputs).

C10733

NOTE:
Refer to Form 33CS-- 67SI for complete
PremierLink configuration, operating sequences and
troubleshooting information. Have a copy of this manual
available at unit start-- up.

Table 5 provides a summary of field connections for units
equipped with Space Sensor. Table 6 provides a summary of
field connections for units equipped with Space Thermostat.

Table 4 – PremierLink Sensor Usage
APPLICATION

OUTDOOR AIR
TEMPERATURE
SENSOR

RETURN AIR
TEMPERATURE
SENSOR

OUTDOOR AIR
ENTHALPY SENSOR

RETURN AIR
ENTHALPY SENSOR

Differential Dry Bulb
Temperature with
PremierLink
(PremierLink requires
4---20 mA Actuator)

Included --CRTEMPSN001A00

Required --33ZCT55SPT
or equivalent

---

---

Single Enthalpy with
PremierLink
(PremierLink requires
4---20mA Actuator)

Included --Not Used

---

Requires --33CSENTHSW

---

Differential Enthalpy
with PremierLink
(PremierLink requires
4---20mA Actuator)

Included --Not Used

---

Requires --33CSENTHSW
or equivalent

Requires --33CSENTSEN
or equivalent

NOTES:
CO2 Sensors (Optional):
33ZCSENCO2 --- Room sensor (adjustable). Aspirator box is required for duct mounting of the sensor.
33ZCASPCO2 --- Aspirator box used for duct--- mounted CO2 room sensor.
33ZCT55CO2 --- Space temperature and CO2 room sensor with override.
33ZCT56CO2 --- Space temperature and CO2 room sensor with override and setpoint.

29

48HC

The PremierLink control is used with EconoMi$er2
(option or accessory) for outdoor air management. The
damper position is controlled directly by the PremierLink
control; EconoMi$er2 has no internal logic device.

48HC

Table 5 – Space Sensor Mode
TB3 TERMINAL
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
LEGEND:
T55
T56
CCN
CMPSAFE
FILTER
FSD
IAQ
OAQ
RH
SFS

---------------------

FIELD CONNECTION
T55---SEN/T56---SEN
RMTOCC
T55---SEN/T56---SEN
CMPSAFE
T56---SET
FSD
LOOP---PWR
SPS
IAQ ---SEN
FILTER
IAQ ---COM/OAQ ---COM/RH ---COM
CCN + (RED)
OAQ ---SEN/RH ---SEN
CCN Gnd (WHT)
AUX OUT(Power Exhaust)
CCN --- (BLK)

INPUT SIGNAL
Analog (10k thermistor)
Discrete, 24VAC
Analog (10k thermistor)
Discrete, 24VAC
Analog (10k thermistor)
Discrete, 24VAC
Analog, 24VDC
Discrete, 24VAC
Analog, 4---20mA
Discrete, 24VAC
Analog, 4---20mA
Digital, , 5VDC
Analog, 4---20mA
Digital, 5VDC
(Output)Discrete 24VAC
Digital, 5VDC

Space Temperature Sensor
Space Temperature Sensor
Carrier Comfort Network (communication bus)
Compressor Safety
Dirty Filter Switch
Fire Shutdown
Indoor Air Quality (CO2)
Outdoor Air Quality (CO2)
Relative Humidity
Supply Fan Status

Table 6 – Thermostat Mode
TB3 TERMINAL
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
LEGEND:
CCN
--G
--IAQ
--OAQ
--RAT
--RH
--W1
--W2
--Y1
--Y2
---

FIELD CONNECTION
RAT SEN
G
RAT SEN
Y1

INPUT SIGNAL
Analog (10k thermistor)
Discrete, 24VAC
Analog (10k thermistor)
Discrete, 24VAC

Y2
LOOP---PWR
W1
IAQ ---SEN
W2
IAQ ---COM/OAQ ---COM/RH ---COM
CCN + (RED)
OAQ ---SEN/RH ---SEN
CCN Gnd (WHT)
AUX OUT (Power Exhaust)
CCN --- (BLK)

Discrete, 24VAC
Analog, 24VDC
Discrete, 24VAC
Analog, 4---20mA
Discrete, 24VAC
Analog, 4---20mA
Digital, 5VDC
Analog, 4---20mA
Digital, 5VDC
(Output) Discrete 24VAC
Digital, 5VDC

Carrier Comfort Network (communication bus)
Thermostat Fan
Indoor Air Quality (CO2)
Outdoor Air Quality (CO2)
Return Air Temperature
Relative Humidity
Thermostat Heat Stage 1
Thermostat Heat Stage 2
Thermostat Cool Stage 1
Thermostat Cool Stage 2

30

Space Sensors —
SEN

The PremierLink controller is factory-- shipped configured
for Space Sensor Mode. A Carrier T-- 55 or T-- 56 space
sensor must be used. T-- 55 space temperature sensor
provides a signal of space temperature to the PremierLink
control. T-- 56 provides same space temperature signal plus
it allows for adjustment of space temperature setpoints
from the face of the sensor by the occupants.

SEN

TB3

PL

1

J6-7

TB3
3

PL
J6-6

5

J6-5

Jumper

SET
SET

C10022

Fig. 44 - PremierLink T-- 56 Sensor

2

4

3

5

A 7-- wire thermostat connection requires a 24-- v power
source and a common connection. Use the R and C
terminals on the CTB’s THERMOSTAT connection strip
for these. Connect the thermostat’s Y1, Y2, W1, W2 and
G terminals to PremierLink TB3 as shown in Fig. 45.

6

RED(+)
WHT(GND)
BLK(-)

CCN COM

SEN
SW1

BRN (GND)
BLU (SPT)

SENSOR WIRING

If the 48HC unit is equipped with factory-- installed smoke
detector(s), disconnect the factory BLU lead at TB3-- 6
(Y2) before connecting the thermostat. Identify the BLU
lead originating at CTB-- DDC-- 1; disconnect at TB3-- 6
and tape off. Confirm that the second BLU lead at TB3-- 6
remains connected to PremierLink J4-- 8.
C08201

Fig. 41 - T-- 55 Space Temperature Sensor Wiring

Connect T-- 55: See Fig. 41 for typical T-- 55 internal
connections. Connect the T-- 55 SEN terminals to TB3
terminals 1 and 3 (see Fig. 42).

SEN
SEN

TB3

PL

1

J6-7

3

J6-6

Fig. 42 - PremierLink T-- 55 Sensor

1

2

3

4

SEN
SW1

5

6
RED(+)
WHT(GND)
BLK(-)

CCN COM

R

G

2

PL
J4-12

Y1

4

J4-10

Y2

6

J4-8

W1

8

J4-6

W2

10

J4-4

C

C

CTB
THERMOSTAT

Fig. 45 - Space Thermostat Connections

C10283

If the 48HC unit has an economizer system and free--cooling
operation is required, a sensor representing Return Air
Temperature must also be connected (field--supplied and
installed). This sensor may be a T--55 Space Sensor (see Fig.
41) installed in the space or in the return duct, or it may be
sensor PNO 33ZCSENSAT, installed in the return duct.
Connect this sensor to TB3--1 and TB3--3 per Fig. 42.

Connect to the CCN bus using a CCN service tool and
navigate to PremierLink Configuration screen for
Operating Mode. Default setting is Sensor Mode (value
1). Change the value to 0 to reconfigure the controller for
Thermostat Mode.

SENSOR WIRING

JUMPER
TERMINALS
AS SHOWN

Cool

R

Configure the Unit for Thermostat Mode —

SET

BLK
(T56)
BRN (GND)
BLU (SPT)

CTB
THERMOSTAT

TB3

C10023

Connect T-- 56: See Fig. 43 for T-- 56 internal connections.
Install a jumper between SEN and SET terminals as
illustrated. Connect T-- 56 terminals to TB3 terminals 1, 3
and 5 (see Fig. 44).

SPACE
THERMOSTAT

Warm

Fig. 43 - T-- 56 Internal Connections

C08202

When the PremierLink is configured for Thermostat
Mode, these functions are not available: Fire Shutdown
(FSD), Remote Occupied (RMTOCC), Compressor Safety
(CMPSAFE), Supply Fan Status (SFS), and Filter Pressure
Switch (FILTER).
31

48HC

Connect Thermostat —
1

Economizer Controls
Indoor Air Quality (CO2) Sensor —
The indoor air quality sensor accessory monitors space
carbon dioxide (CO2) levels. This information is used to
monitor IAQ levels. Several types of sensors are available,
for wall mounting in the space or in return duct, with and
without LCD display, and in combination with space
temperature sensors. Sensors use infrared technology to
measure the levels of CO2 present in the space air.

48HC

The CO2 sensors are all factory set for a range of 0 to
2000 ppm and a linear mA output of 4 to 20. Refer to the
instructions supplied with the CO2 sensor for electrical
requirements and terminal locations. See Fig. 46 for
typical CO2 sensor wiring schematic.

To connect the sensor to the control, identify the positive
(4 to 20 mA) and ground (SIG COM) terminals on the
sensor. See Fig. 46. Connect the 4-- 20 mA terminal to
terminal TB3-- 9 and connect the SIG COM terminal to
terminal TB3-- 11. See Fig. 47.
IAQ Sensor

J4
4-20mA

TB3
9

PL
J5-5

SIG COM

TB3
11

J5-3

24 VAC

Fig. 47 - Indoor CO2 Sensor (33ZCSENCO2)
Connections

C11156

Refer to Form 33CS-- 67SI, PremierLink Installation,
Start-- up, and Configuration Instructions, for detailed
configuration information.
Outdoor Air Quality Sensor (PNO 33ZCSENCO2 plus
weatherproof enclosure) —
The outdoor air CO2 sensor is designed to monitor carbon
dioxide (CO2) levels in the outside ventilation air and
interface with the ventilation damper in an HVAC system.
The OAQ sensor is packaged with an outdoor cover. See
Fig. 48. The outdoor air CO2 sensor must be located in the
economizer outside air hood.

+ 0-10VDC
- SIG COM
+ 4-20mA
ALARM
NC
COM RELAY
NO CONTACTS

}

H G 24 VAC
OR
+ - 24 VDC

2 1
J3

8765432 1
J4

C08635

Fig. 46 - Indoor/Outdoor Air Quality (CO2) Sensor
(33ZCSENCO2) - Typical Wiring Diagram

To accurately monitor the quality of the air in the
conditioned air space, locate the sensor near a return-- air
grille (if present) so it senses the concentration of CO2
leaving the space. The sensor should be mounted in a
location to avoid direct breath contact.
Do not mount the IAQ sensor in drafty areas such as near
supply ducts, open windows, fans, or over heat sources.
Allow at least 3 ft (0.9 m) between the sensor and any
corner. Avoid mounting the sensor where it is influenced
by the supply air; the sensor gives inaccurate readings if
the supply air is blown directly onto the sensor or if the
supply air does not have a chance to mix with the room air
before it is drawn into the return airstream.
Wiring the Indoor Air Quality Sensor: For each sensor,
use two 2-- conductor 18 AWG (American Wire Gage)
twisted-- pair cables (unshielded) to connect the separate
isolated 24 vac power source to the sensor and to connect
the sensor to the control board terminals.

COVER REMOVED

SIDE VIEW

Fig. 48 - Outdoor Air Quality Sensor Cover

C07135

Wiring the Outdoor Air CO2 Sensor: A dedicated
power supply is required for this sensor. A two-- wire cable
is required to wire the dedicated power supply for the
sensor. The two wires should be connected to the power
supply and terminals 1 and 2.
To connect the sensor to the control, identify the positive
(4 to 20 mA) and ground (SIG COM) terminals on the
OAQ sensor. See Fig. 46. Connect the 4 to 20 mA
terminal to the TB3-- 13 terminal of the 48HC. Connect the
SIG COM terminal to the TB3-- 11 terminal of the 48HC.
See Fig. 49.

32

TB3
13

PL
J5-2

SIG COM

TB3
11

J5-3

24 VAC

Fig. 49 - Outdoor CO2 Sensor Connections

C11157

Space Relative Humidity Sensor or Humidistat
Connections —
Space Relative Humidity Sensor connections: The
accessory space relative humidity sensor (33ZCSENSRH-01)
is installed on an interior wall to measure the relative
humidity of the air within the occupied space.
The use of a standard 2 X 4 inch electrical box to
accommodate the wiring is recommended for installation.
The sensor can be mounted directly on the wall, if
acceptable by local codes.

TB3-7
TB3-13

CAUTION

BLACK

!

The sensor must be mounted vertically on the wall. The
Carrier logo should be orientated correctly when the
sensor is properly mounted.
Avoid corner locations. Allow at least 4 ft between the
sensor and any corner. Airflow near corners tends to be
reduced, resulting in erratic sensor readings. The sensor
should be vertically mounted approximately 5 ft up from
the floor, beside the space temperature sensor.
For wiring distances up to 500 feet, use a 3-- conductor, 18
or 20 AWG cable. ACCN communication cable can be
used, although the shield is not required. The shield must
be removed from the sensor end of the cable if this cable
is used. See Fig. 51 for wiring details.

UNIT DAMAGE HAZARD
Failure to follow this caution may result in
permanent damage to the sensor.
DO NOT clean or touch the sensing element with
chemical solvents as they can permanently damage the
sensor.

!

Io Vin Gnd Vo

CAUTION

C11085

UNIT PERFORMANCE HAZARD
Failure to follow this caution will result in inaccurate
sensor readings.
DO NOT mount the sensor in drafty areas such as near
heating or air--conditioning ducts, open windows, fans,
or over heat sources such as baseboard heaters,
radiators, or wall--mounted dimmers. Sensors mounted
in those areas will produce inaccurate readings.
If the sensor is installed directly on a wall service, install the
humidity sensor using 2 screws and 2 hollow wall anchors
(field supplied). Do not over tighten screws. See Fig. 50.

MOUNTING
HOLES
Io

Vin

Gnd

WIRING
OPENING

Vo

Fig. 51 - Space Relative Humidity Sensor Connection

The power for the sensor is provided by the PremierLink
control on terminal J5-- 4 (+33 to +35vdc).
To wire the sensor:
1. At the sensor, remove 4 inches of the jacket from the
cable. Strip 1/4 inch of insulation from each conductor. Route the cable through the wire clearance opening in the center of the sensor. See Fig. 50.
2. Connect a field-- supplied BLACK wire to the sensor
screw terminal marked Vin.
3. Connect a field-- supplied RED wire into the sensor
screw terminal marked Io.
4. Connect the field-- supplied RED wire from the sensor
to TB3-- 13.
5. Connect the field-- supplied BLACK wire from the
sensor to TB3-- 7.
Humidistat connections: A humidistat can not be directly
connected to the PremierLink controller. Follow the
instructions on pages 24 & 25 to connect a humidistat or a
thermostat as an electromechanical device.

SW2
1

2

3

4

5

6

ON

C11084

Fig. 50 - Space Relative Humidity Sensor Installation

33

48HC

4-20mA

RED

OAQ Sensor

Smoke Detector/Fire Shutdown (FSD) —
This function is available only when PremierLink is
configured for (Space) Sensor Mode. The unit is
factory-- wired for PremierLink FSD operation when
PremierLink is factory-- installed.

Connect one side of the switch’s NO contact set to CTB’s
THERMOSTAT-- R terminal. Connect the other side of the
NO contact set to TB3-- 8. Setpoint for Supply Fan Status
is set at the switch. See Fig. 53.
Fan (Pressure) Switch (NO, close on rise in pressure)
CTB
Thermostat

On 48HC units equipped with factory--installed Smoke
Detector(s), the smoke detector controller implements the
unit shutdown through its NC contact set connected to the
unit’s CTB input. The FSD function is initiated via the
smoke detector’s Alarm NO contact set. The PremierLink
communicates the smoke detector’s tripped status to the
CCN building control. See Figs. 38 and 39, the PremierLink
wiring schematics.

R
TB3
8

C10287

Fig. 53 - PremierLink Wiring Fan Pressure Switch
Connection

48HC

Filter Status Switch —
This function is available only when PremierLink is
configured for (Space) Sensor Mode.
PremierLink control can monitor return filter status in two
ways: By monitoring a field-- supplied/installed filter
pressure switch or via supply fan runtime hours.
Using switch input: Install the dirty filter pressure switch
according to switch manufacturer’s instructions, to
measure pressure drop across the unit’s return filters.
Connect one side of the switch’s NO contact set to CTB’s
THERMOSTAT-- R terminal. Connect the other side of the
NO contact set to TB3-- 10. Setpoint for Dirty Filter is set
at the switch. See Fig. 52.

Remote Occupied Switch —
The PremierLink control permits a remote timeclock to
override the control’s on-- board occupancy schedule and
place the unit into Occupied mode. This function may also
provide a “Door Switch” time delay function that will
terminate cooling and heating functions after a 2-- 20
minute delay.
Connect one side of the NO contact set on the timeclock
to CTB’s THERMOSTAT-- R terminal. Connect the other
side of the timeclock contact to the unit’s TB3-- 2 terminal.
Remote Occupied

LCTB
Thermostat
R

Time Clock

TB3
2

Filter Switch (NO, close on rising pressure (high drop))
CTB
Thermostat

PL
J4-12
C10288

R
TB3
10

PL
J4-6

Fig. 54 - PremierLink Wiring Remote Occupied
PL
J4-4
C10286

Fig. 52 - PremierLink Filter Switch Connection

When the filter switch’s NO contact set closes as filter
pressure drop increases (indicating dirt-- laden filters), the
input signal to PremierLink causes the filter status point to
read “DIRTY”.

Refer to Form 33CS-- 67SI for additional information on
configuring the PremierLink control for Door Switch
timer function.
Power Exhaust (output) —
Connect the accessory Power Exhaust contactor coils(s)
per Fig. 55.
Power Exhaust

Using Filter Timer Hours: Refer to Form 33CS-- 67SI for
instructions on using the PremierLink Configuration
screens and on unit alarm sequence.

PER

Supply Fan Status Switch —
The PremierLink control can monitor supply fan operation
through a field-- supplied/installed differential pressure
switch. This sequence will prevent (or interrupt) operation
of unit cooling, heating and economizer functions until
the pressure switch contacts are closed indicating proper
supply fan operation.
Install the differential pressure switch in the supply fan
section according to switch manufacturer’s instructions.
Arrange the switch contact to be open on no flow and to
close as pressure rises indicating fan operation.

VIO

TB3
15

BRN

CTB
THERMOSTAT
C

PL
J8-3

C11158

Fig. 55 - PremierLink Power Exhaust Output
Connection

NOTE: The Power Exhaust and Humidi-- MiZerR options
can not be used with PremierLink at the same time as both
options require connection at TB3-- 15 (AUX OUT).

34

The PremierLink controller connects to the bus in a daisy
chain arrangement. Negative pins on each component
must be connected to respective negative pins, and
likewise, positive pins on each component must be
connected to respective positive pins. The controller
signal pins must be wired to the signal ground pins.
Wiring connections for CCN must be made at the 3-- pin
plug.
At any baud (9600, 19200, 38400 baud), the number of
controllers is limited to 239 devices maximum. Bus length
may not exceed 4000 ft (1219 m), with no more than 60
total devices on any 1000-- ft section. Optically isolated
RS-- 485 repeaters are required every 1000 ft (305 m).

The communication bus shields must be tied together at
each system element. If the communication bus is entirely
within one building, the resulting continuous shield must
be connected to ground at only one single point. If the
communication bus cable exits from one building and
enters another building, the shields must be connected to
the grounds at a lightning suppressor in each building (one
point only).
Connecting CCN Bus:
NOTE: When connecting the communication bus cable,
a color code system for the entire network is
recommended to simplify installation and checkout. See
Table 8 for the recommended color code.
Table 8 – Color Code Recommendations

NOTE: Carrier device default is 9600 baud.
Communications Bus Wire Specifications: The CCN
Communication Bus wiring is field-- supplied and
field-- installed. It consists of shielded 3-- conductor cable
with drain (ground) wire. The cable selected must be
identical to the CCN Communication Bus wire used for
the entire network.
See Table 7 for recommended cable.
Table 7 – Recommended Cables
MANUFACTURER

CABLE PART NO.

Alpha

2413 or 5463

American

A22503

Belden

8772

Columbia

02525

NOTE: Conductors and drain wire must be at least 20
AWG, stranded, and tinned copper. Individual conductors
must be insulated with PVC, PVC/nylon, vinyl, Teflon, or
polyethylene. An aluminum/polyester 100% foil shield
and an outer jacket of PVC, PVC/nylon, chrome vinyl, or
Teflon with a minimum operating temperature range of
- 20_C (-- 4_F) to 60_C (140_F) is required. Do not run
communication wire in the same conduit as or next to any
AC voltage wiring.

SIGNAL TYPE

CCN BUS WIRE
COLOR

CCN PLUG PIN
NUMBER

+

Red

1

Ground

White

2

---

Black

3

Connect the CCN (+) lead (typically RED) to the unit’s
TB3-- 12 terminal. Connect the CCN (ground) lead
(typically WHT) to the unit’s TB3-- 14 terminal. Connect
the CCN (-- ) lead (typically BLK) to the unit’s TB3-- 16
terminal. See Fig. 56.
CCN Bus
+ (RED)

TB3
12

PL
J2-1

GND (WHT)

TB3
14

J2-2

– (BLK)

TB3
16

J2-3

Fig. 56 - PremierLink CCN Bus Connections

35

C10290

48HC

CCN Communication Bus —

RTU Open Control System

Refer to Table 9, RTU Open Controller Inputs and Outputs
for locations of all connections to the RTU Open board.

48HC

The RTU Open control is factory-- mounted in the 48HC
unit’s main control box, to the right of the CTB. See
Fig. 37. Factory wiring is completed through harnesses
connected to the CTB. Field connections for RTU Open
sensors will be made at the Phoenix connectors on the
RTU Open board. The factory-- installed RTU Open
control includes the supply-- air temperature (SAT) sensor.
The outdoor air temperature (OAT) sensor is included in
the FIOP/accessory EconoMi$er2 package.

The RTU Open controller is an integrated component of the
Carrier rooftop unit. Its internal application programming
provides optimum performance and energy efficiency. RTU
Open enables the unit to run in 100% stand--alone control
mode, Carrier’s I--Vu Open network, or a Third Party
Building Automation System (BAS). On--board DIP
switches allow you to select your protocol (and baud rate) of
choice among the four most popular protocols in use today:
BACnet, Modbus, Johnson N2 and LonWorks. (See Fig. 57.)

Fig. 57 - RTU Open Multi-- Protocol Control Board

36

C10811

48HC
Fig. 58 - RTU Open System Control Wiring Diagram

37

C11142

48HC

Fig. 59 - RTU Open System Control Wiring Diagram with Humidi-- MiZerR

38

C11143

Table 9 – RTU Open Controller Inputs and Outputs

Space Temp / Zone Temp
Supply Air Temperature
Outdoor Air Temperature
Space Temperature Offset Pot
Safety Chain Feedback
Compressor Safety Status
Fire Shutdown Status
Enthalpy Status
Humidistat Input Status
Indoor Air CO2
Outdoor Air CO2
Space Relative Humidity
Supply Fan Status*
Filter Status*
Door Contact Input*
Occupancy Contact*

BACnet OBJECT
NAME

TYPE OF I/O

DEDICATED INPUTS
zone_temp
AI (10K Thermistor)
sa_temp
AI (10K Thermistor)
oa_temp
AI (10K Thermistor)
stpt_adj_offset
AI (100K Potentiometer)
safety_status
DI (24 VAC)
comp_status
DI (24 VAC)
firedown_status
DI (24 VAC)
enthalpy_status
DI (24 VAC)
humstat_status
DI (24 VAC)
CONFIGURABLE INPUTS
iaq
AI (4--- 20 ma)
oaq
AI (4--- 20 ma)
space_rh
AI (4--- 20 ma)
sfan_status
DI (24 VAC)
filter_status
DI (24 VAC)
door_contact_status
DI (24 VAC)
occ_contact_status
DI (24 VAC)

CONNECTION PIN
NUMBER(S)
J20--- 1, 2
J2--- 1, 2
J2--- 3, 4
J20--- 3
J1--- 9
J1--- 2
J1--- 10
J2--- 6
J5--- 7

J4--- 2 or J4--- 5

J5--- 1 or J5--- 3 or
J5 5 or J5--- 7

OUTPUTS
Economizer Output
Supply Fan Relay State
Compressor 1 Relay State
Compressor 2 Relay State
Heat Stage 1 Relay State
Heat Stage 2 Relay State
Power Exhaust Relay State
Dehumidification Relay State

econ_output
sfan
comp_1
comp_2
heat_1
heat_2
pexh
dehum

AO (4--- 20ma)
DO Relay (24VAC , 1A)
DO Relay (24VAC , 1A)
DO Relay (24VAC , 1A)
DO Relay (24VAC , 1A)
DO Relay (24VAC , 1A)
DO Relay (24VAC , 1A)
DO Relay (24VAC, 1A)

J2--- 5
J1--- 4
J1--- 8
J1--- 7
J1--- 6
J1--- 5
J11--- 3
J11--- 7, 8

LEGEND
AI --- Analog Input
AO --- Analog Output
DI --- Discrete Input
DO --- Discrete Output
* These inputs (if installed) take the place of the default input on the specific channel according to schematic.
Parallel pins J5 ---1 = J2 ---6, J5 ---3 = J1 ---10, J5 ---5 = J1 ---2 are used for field---installation.

The RTU Open controller requires the use of a Carrier
space sensor. A standard thermostat cannot be used with
the RTU Open system.
Supply Air Temperature (SAT) Sensor —
On FIOP--equipped 48HC unit, the unit is supplied with a
supply--air temperature (SAT) sensor (33ZCSENSAT). This
sensor is a tubular probe type, approx 6--inches (12.7 mm) in
length. It is a nominal 10--k ohm thermistor.
The SAT is factory--wired. The SAT probe is wire--tied to the
supply--air opening (on the horizontal opening end) in its
shipping position. Remove the sensor for installation.
Re--position the sensor in the flange of the supply--air
opening or in the supply air duct (as required by local
codes). Drill or punch a 1/2- in. hole in the flange or duct.
Use two field--supplied, self--drilling screws to secure the
sensor probe in a horizontal orientation. See Fig. 40.
Outdoor Air Temperature (OAT) Sensor —
The OAT is factory--mounted in the EconoMi$er2 (FIOP or
accessory). It is a nominal 10k ohm thermistor attached to
an eyelet mounting ring.

EconoMi$er2 —
The RTU Open control is used with EconoMi$er2 (option
or accessory) for outdoor air management. The damper
position is controlled directly by the RTU Open control;
EconoMi$er2 has no internal logic device.
Outdoor air management functions can be enhanced with
field-- installation of these accessory control devices:
Enthalpy control (outdoor air or differential sensors)
Space CO2 sensor
Outdoor air CO2 sensor

Field Connections
Field connections for accessory sensors and input devices
are made the RTU Open, at plugs J1, J2, J4, J5, J11 and
J20. All field control wiring that connects to the RTU
Open must be routed through the raceway built into the
corner post as shown in Fig. 31. The raceway provides the
UL required clearance between high-- and low--voltage
wiring. Pass the control wires through the hole provided in
the corner post, then feed the wires thorough the raceway
39

48HC

POINT NAME

to the RTU Open. Connect to the wires to the removable
Phoenix connectors and then reconnect the connectors to
the board.

48HC

Space Temperature (SPT) Sensors —
There are two types of SPT sensors available from Carrier,
resistive input non-communicating (T55, T56, and T59)
and Rnet communicating (SPS, SPPL, SPP, and SPPF)
sensors. Each type has a variety of options consisting of:
timed override button, set point adjustment, a LCD
screen, and communication tie in. Space temperature can
be also be written to from a building network or zoning
system. However, it is still recommended that return air
duct sensor be installed to allow stand-alone operation for
back-up. Refer to the configuration section for details on
controller configurations associated with space sensors.
S 33ZCT55SPT, space temperature sensor with override
button (T-- 55)

Connect T-- 59: The T-- 59 space sensor requires a
separate, isolated power supply of 24 VAC. See Fig. 62
for internal connections at the T-- 59. Connect the SEN
terminal (BLU) to RTU Open J20-- 1. Connect the COM
terminal (BRN) to J20-- 2. Connect the SET terminal (STO
or BLK) to J20-- 3.
BLK (STO)

BRN (COM)

BLU (SPT)

OR

SET

SEN

OPB

COM- PWR+

J20-3

J20-2

SENSOR
WIRING

J20-1

S 33ZCT56SPT, space temperature sensor with override
button and setpoint adjustment (T-- 56)
S 33ZCT59SPT, space temperature sensor with LCD
(liquid crystal display) screen, override button, and
setpoint adjustment (T-- 59)

24 VAC
NOTE: Must use a separate isolated transformer.

Use 20 gauge wire to connect the sensor to the controller.
The wire is suitable for distances of up to 500 ft. (152 m).
Use a three-- conductor shielded cable for the sensor and
setpoint adjustment connections. If the setpoint
adjustment (slidebar) is not required, then an unshielded,
18 or 20 gauge, two-- conductor, twisted pair cable may be
used.
Connect T-- 55: See Fig. 41 for typical T-- 55 internal
connections. Connect the T-- 55 SEN terminals to RTU
Open J20-- 1 and J20-- 2. See Fig. 60.
J20-1

SEN

POWER
WIRING

C10291

Fig. 62 - Space Temperature Sensor Typical Wiring
(33ZCT59SPT)
Indoor Air Quality (CO2) Sensor —

The indoor air quality sensor accessory monitors space
carbon dioxide (CO2) levels. This information is used to
monitor IAQ levels. Several types of sensors are available,
for wall mounting in the space or in return duct, with and
without LCD display, and in combination with space
temperature sensors. Sensors use infrared technology to
measure the levels of CO2 present in the space air.

Fig. 60 - RTU Open T-- 55 Sensor Connections

The CO2 sensors are all factory set for a range of 0 to
2000 ppm and a linear mA output of 4 to 20. Refer to the
instructions supplied with the CO2 sensor for electrical
requirements and terminal locations. See Fig. 46 for
typical CO2 sensor wiring schematic.

Connect T-- 56: See Fig. 43 for T-- 56 internal connections.
Install a jumper between SEN and SET terminals as
illustrated. Connect T-- 56 terminals to RTU Open J20-- 1,
J20-- 2 and J20-- 3 per Fig. 61.

To accurately monitor the quality of the air in the
conditioned air space, locate the sensor near a return-- air
grille (if present) so it senses the concentration of CO2
leaving the space. The sensor should be mounted in a
location to avoid direct breath contact.

J20-2

SEN

C08460

SEN

Do not mount the IAQ sensor in drafty areas such as near
supply ducts, open windows, fans, or over heat sources.
Allow at least 3 ft (0.9 m) between the sensor and any
corner. Avoid mounting the sensor where it is influenced
by the supply air; the sensor gives inaccurate readings if
the supply air is blown directly onto the sensor or if the
supply air does not have a chance to mix with the room air
before it is drawn into the return airstream.

J20-1

SEN

J20-2
Jumper

SET
SET

J20-3
C08461

Fig. 61 - RTU Open T-- 56 Sensor Connections

Wiring the Indoor Air Quality Sensor: For each sensor,
use two 2-- conductor 18 AWG (American Wire Gage)
twisted-- pair cables (unshielded) to connect the separate
40

To connect the sensor to the control, identify the positive
(4 to 20 mA) and ground (SIG COM) terminals on the
sensor. See Fig. 46. Connect the 4-- 20 mA terminal to
RTU Open terminal J4-- 2 and connect the SIG COM
terminal to RTU Open terminal J4-- 3. See Fig. 63.
IAQ Sensor
4-20mA

J4-2

SIG COM

J4-3

24 VAC

Fig. 63 - RTU Open / Indoor CO2 Sensor
(33ZCSENCO2) Connections

C10738

Outdoor Air Quality Sensor (PNO 33ZCSENCO2 plus
weatherproof enclosure) —
The outdoor air CO2 sensor is designed to monitor carbon
dioxide (CO2) levels in the outside ventilation air and
interface with the ventilation damper in an HVAC system.
The OAQ sensor is packaged with an outdoor cover. See
Fig. 48. The outdoor air CO2 sensor must be located in the
economizer outside air hood.
Wiring the Outdoor Air CO2 Sensor: A dedicated
power supply is required for this sensor. A two-- wire cable
is required to wire the dedicated power supply for the
sensor. The two wires should be connected to the power
supply and terminals 1 and 2.
To connect the sensor to the control, identify the positive
(4 to 20 mA) and ground (SIG COM) terminals on the
OAQ sensor. See Fig. 46. Connect the 4 to 20 mA
terminal to RTU Open terminal J4-- 5. Connect the SIG
COM terminal to RTU Open terminal J4-- 6. See Fig. 64.

Space Relative Humidity Sensor or Humidistat —
Humidi-- MiZerR Control Wiring: In units equipped
with the Humidi-- MiZer option there are two pink (PNK)
wires loose in the control box used to control the
dehumidification function of the unit. These pink wires
are meant to be tied to a space humidistat or thermidistat
on an electromechanical unit. On RTU Open equipped
units these pink wires must be connected to J11-- 7 & 8 to
allow the Open board to operate the dehumidification
function for the unit. Disconnect the J11 Phoenix style
connector from the board and use the plug screws to
secure the pink wires in pins 7 and 8, reconnect the plug
to the board at J11.
Relative Humidity Sensors (Space or Duct Mounted):
The accessory space humidity sensor (33ZCSENSRH-01)
or duct humidity sensor (33ZCSENDRH-01) is used to
measure the relative humidity of air within the space or
return air duct. The RH reading is used to control the
Humidi-- MiZer option of the rooftop unit. For wiring
distances up to 500 ft (152 m), use a 3-- conductor, 18 or
20 AWG shielded cable. The shield must be removed
from the sensor end of the cable and grounded at the unit
end. The current loop power for sensor is provided by the
RTU Open controller as 24vdc. Refer to the instructions
supplied with the RH sensor for the electrical
requirements and terminal locations. RTU Open
configurations must be changed after adding an RH
sensor. See Fig. 65 and 66 for typical RH sensor wiring.
S J4-- 1 or J4-- 4 = 24vdc loop power
S J4-- 2 or J4-- 5 = 4-- 20mA signal input
NOTE: The factory default for dehumidification control
is normally open humidistat.

MOUNTING
HOLES
Io

Vin

Gnd

WIRING
OPENING

Vo

OAQ Sensor/RH Sensor

SIG COM

J4-6

24 VAC
3

4

5

6

C10739
ON

Fig. 64 - RTU Open / Outdoor CO2 Sensor
(33ZCSENCO2) Connections

SW2
2

J4-5

1

4-20mA

Vin - J4-1 or J4-4 24Vdc
Io - J4-2 or J4-5 -20mA output
C11087

Fig. 65 - Space Relative Humidity Sensor Typical Wiring

41

48HC

isolated 24 vac power source to the sensor and to connect
the sensor to the control board terminals.

J4-1 or J4-4 + 24 VDC Supply Voltage
J4-2 or J4-5 (-) 4 to 20 mA Current Loop Output
to RTU-OPEN
Relative Humidity Sensor
(Polarized Male Connector)
SPAN
ZERO

48HC

4-20 VAC GND 0-5V
mA or
or
VDC
0-10V

Fig. 66 - Duct Relative Humidity Sensor Typical Wiring
Humidistat: The accessory humidistat provides the RTU
Open insight to the relative humidity in the space. The
humidistat reads the RH level in the space and compares it
to its setpoint to operate a dry contact. The humidistat is a
dedicated input on the configurable input 9 and tells the
RTU Open when the RH level is HIGH or LOW. The
normal condition for humidity is LOW. A normally open
humidistat is the factory default control for the
Humidi-- MiZerR option.
To wire in the field:
S J5-- 8 = 24 VAC source for dry contact
S J5-- 7 = Signal input
Smoke Detector/Fire Shutdown (FSD) —
On 48HC units equipped with factory--installed Smoke
Detector(s), the smoke detector controller implements the
unit shutdown through its NC contact set connected to the
unit’s CTB input. The FSD function is initiated via the
smoke detector’s Alarm NO contact set. The RTU Open
controller communicates the smoke detector’s tripped status
to the BAS building control. See Figs. 58 and 59, the RTU
Open wiring schematics.
The
Fire
Shutdown
Switch
configuration,
identifies the
MENU→Config→Inputs→input 5,
normally open status of this input when there is no fire
alarm.
Connecting Discrete Inputs —
Filter Status: The filter status accessory is a
field-- installed accessory. This accessory detects plugged
filters. When installing this accessory, the unit must be
configured
for
filter
status
by
setting
MENU→Config→Inputs→input 3, 5, 8, or 9 to Filter
Status and normally open (N/O) or normally closed (N/C).
Input 8 or 9 is recommended for easy of installation. Refer
to Fig. 57 and Fig. 58 or 59 for wire terminations at J5.

C10839

Fan Status: The fan status accessory is a field-- installed
accessory. This accessory detects when the indoor fan is
blowing air. When installing this accessory, the unit must
be
configured
for
fan
status
by
setting
MENU→Config→Inputs→input 3, 5, 8, or 9 to Fan
Status and normally open (N/O) or normally closed (N/C).
Input 8 or 9 is recommended for easy of installation. Refer
to Fig. 57 and Fig. 58 or 59 for wire terminations at J5.
Remote Occupancy: The remote occupancy accessory is
a field-- installed accessory. This accessory overrides the
unoccupied mode and puts the unit in occupied mode.
When installing this accessory, the unit must be
configured for
remote occupancy
by setting
MENU→Config→Inputs→input 3, 5, 8, or 9 to Remote
Occupancy and normally open (N/O) or normally closed
(N/C).
Also set MENU→Schedules→occupancy source to DI
on/off. Input 8 or 9 is recommended for easy of
installation. Refer to Fig. 57 and Table 9 for wire
terminations at J5.
Power Exhaust (output): The relay used by the RTU
Open board to control power exhaust is a dry contact
which means it does not have 24vac. This 24vac must be
connected to the relay to allow it to operate the power
exhaust relay in the PE accessory. A 24vac source must be
provided to J11-- 2 on the RTU Open control board. This
can be provided by the unit’s transformer from various
sources. The “R” terminal on the unit’s low voltage
terminal board (LVTB) is a logical source. Refer to Fig.
57 and Fig. 58 or 59 for wire terminations at J11.

42

Communication Wiring -- Protocols
General —
Protocols are the communication languages spoken by
control devices. The main purpose of a protocol is to
communicate information in the most efficient method
possible. Different protocols exist to provide different
kinds of information for different applications. In the BAS
application, many different protocols are used, depending
on manufacturer. Protocols do not change the function of
a controller; just make the front end user different.

The RTU Open can be set to communicate on four
different protocols: BACnet, Modbus, N2, and LonWorks.
Switch 3 (SW3) on the board is used to set protocol and
baud rate. Switches 1 and 2 (SW1 and SW2) are used to
set the board’s network address. See Fig. 67 and 68 for
protocol switch settings and address switches. The 3rd
party connection to the RTU Open is through plug J19.
See Fig. 69 for wiring.
NOTE: Power must be cycled after changing the SW1-- 3
switch settings.
Refer to the RTU Open Controller Integration Guide
(Catalog No. 11--808--428--01) for more detailed information
on protocols, 3rd party wiring, and networking.

PROTOCOL

DS8

DS7

DS6

DS5

DS4

DS3

DS2

DS1

BACnet MS/TP
(Master)

Unused

OFF

OFF

OFF

ON

OFF

Select Baud

Select Baud

Modbus
(Slave)

Unused

OFF

OFF

ON

ON

OFF

Select Baud

Select Baud

N2
(Slave)

Unused

OFF

OFF

OFF

ON

ON

OFF

OFF

LonWorks

Unused

ON

ON

OFF

ON

OFF

OFF

OFF

NOTE:
DS = Dip Switch
BACnet MS/TP SW3 example shown

Baud Rate Selections
BAUD RATE

DS2

DS1

9600

OFF

OFF

19,200

ON

OFF

38,400

OFF

ON

76,800

ON

ON

C07166

Fig. 67 - RTU Open SW3 Dip Switch Settings

Fig. 68 - RTU Open Address Switches

C10815

Fig. 69 - Network Wiring

43

C10816

48HC

SW3 Protocol Selection

Local Access —

Virtual BACview: Virtual BACview is a freeware computer

BACview6 Handheld: The BACview6 is a keypad/display
interface used to connect to the RTU Open to access the
control information, read sensor values, and test the RTU,
see Fig. 70. This is an accessory interface that does not
come with the RTU Open controller and can only be used
at the unit. Connect the BACview6 to the RTU Open J12
local access port. There are 2 password protected levels in
the display (User and Admin). The user password is
defaulted to 0000 but can be changed. The Admin
password is 1111 and cannot be changed. There is a 10
minute auto logout if a screen is idle. See Form
48-- 50HCTQ-- 01T, Appendix A for navigation and screen
content.

RTU Open Troubleshooting —

program that functions as the BACview6 Handheld. The
USB Link interface (USB-- L) is required to connect a
computer to the RTU Open board. The link cable connects
a USB port to the J12 local access port. This program
functions and operates identical to the handheld.

48HC

Communication LEDs: The LEDs indicate if the
controller is speaking to the devices on the network. The
LEDs should reflect communication traffic based on the
baud rate set. The higher the baud rate the more solid the
LEDs will appear. See Table 10.

Access Port

P1

P1

Protocol Selector

RTU Open
J12

Cable

P5

P5
BACview6 Local Access Cable

Fig. 70 - BACview6 Handheld Connections

44

C10812

Table 10 – LEDs
The LEDs on the RTU Open Control Board (see Fig. 57) show the status of certain functions:
If this LED is on...

Status is...

Power

RTU Open has power

Rx

RTU Open is receiving data from the network segment

Tx

RTU Open is transmitting data over the network segment

DO#

The digital output is active
The Run and Error LEDs indicate control module and network status
And Error LED shows...

Status is...

2 flashes per second

Off

Normal

2 flashes per second

2 flashes,
alternating with Run LED

Five minute auto---restart delay after system error

2 flashes per second

3 flashes,
then off

Control module has just been formatted

2 flashes per second

4 flashes,
then pause

Two or more devices on this network have the
same ARC156 network address

2 flashes per second

On

Exec halted after frequent system errors or
control programs halted

5 flashes per second

On

Exec start---up aborted, Boot is running

5 flashes per second

Off

Firmware transfer in progress, Boot is running

7 flashes per second

7 flashes per second, alternating with
Run LED

Ten second recovery period after brownout

14 flashes per second

14 flashes per second,
alternating with Run LED

Brownout

On

Failure. Try the following solutions:
S
Turn RTU Open off, then on.
S
Format RTU Open.
S
Download memory to RTU Open.
S
Replace RTU Open.

On

NOTE:
Refer to Catalog No. 48--50HCTQ--01T for
complete configuration of RTU Open, operating sequences
and troubleshooting information. Refer to RTU Open
Controller Integration Guide (Catalog No. 11--808--428--01)
for details on configuration and troubleshooting of connected
networks. Have a copy of these manuals available at unit
start--up.

48HC

If Run LED shows...

Enthalpy
Switch

Outdoor Air Enthalpy Control
(PNO 33CSENTHSW)

24V

RED

PL6-1 (24-V)

GND

BLK

PL6-4 (COM)

LOW

GRA

7

CTB ECON
(P’LINK: to J4-2) or
(RTU Open: to J2-6)

Factory Wiring Harness
C11160

Fig. 71 - Enthalpy Switch (33CSENTHSW) Connections
The enthalpy control (33CSENTHSW) is available as a
field-- installed accessory to be used with the EconoMi$er2
damper system. The outdoor air enthalpy sensor is part of
the enthalpy control. (The separate field-- installed
accessory return air enthalpy sensor (33CSENTSEN) is
required for differential enthalpy control. See Fig. 71.)
Locate the enthalpy control in the economizer next to the
Actuator Motor. Locate two GRA leads in the factory
harness and connect the gray lead labeled “ESL” to the
terminal labeled “LOW”. See Fig. 71. Connect the
enthalpy control power input terminals to economizer
actuator power leads RED (connect to 24V) and BLK
(connect to GND).

The outdoor enthalpy changeover setpoint is set at the
enthalpy controller.
Differential Enthalpy Control —
Differential enthalpy control is provided by sensing and
comparing the outside air and return air enthalpy
conditions. Install the outdoor air enthalpy control as
described above. Add and install a return air enthalpy
sensor (see Fig. 72).

45

24V

RED

PL6-1 (24-V)

– 4-20
Main

GND

BLK

PL6-4 (COM)

+ VDC
Out

LOW

GRA

7

CTB ECON
(P’LINK: to J4-2) or
(RTU Open: to J2-6)

R
O
TA
TIO
N

Outside Air
Enthalpy Switch

Return Air Sampling Tube
(Shipping Location)

+ 24-36
VDC In
– 4-20 Main
Out

Return Air
Enthalpy
Sensor

C11161

C09102

48HC

Fig. 72 - Outside and Return Air Enthalpy Sensor
Wiring

Fig. 73 - Typical Supply Air Smoke Detector Sensor
Location

To wire the return air enthalpy sensor, perform the
following:
1. Use a 2-- conductor, 18 or 20 AWG, twisted pair cable
to connect the return air enthalpy sensor to the enthalpy controller.
2. Connect the field-- supplied RED wire to (+) spade
connector on the return air enthalpy sensor and the
(+) terminal on the enthalpy controller. Connect the
BLK wire to (-- ) spade connector on the return air enthalpy sensor and the (-- ) terminal on the enthalpy
controller.

Smoke Detectors
Smoke detectors are available as factory-- installed options
on 48HC models. Smoke detectors may be specified for
Supply Air only or for Return Air without or with
economizer or in combination of Supply Air and Return
Air. Return Air smoke detectors are arranged for vertical
return configurations only. The unit is factory-- configured
for immediate smoke detector shutdown operation;
additional wiring or modifications to unit terminal board
may be necessary to complete the unit and smoke detector
configuration to meet project requirements.

Return Air Detector
Sampling Tube
C09135

Fig. 74 - Return Air Sampling Tube Location
in Unit without Economizer

Return Air Sensor Tube Installation –
The return air sampling tube is shipped in the unit s
supply fan section, attached to the blower housing (see
Fig. 73. Its operating location is in the return air section
of the unit (see Fig. 74, unit without economizer, or
Fig. 75, unit with economizer), inserted into the return air
sensor module housing which protrudes through the back
of the control box.
Return Air Detector
Sampling Tube
C09136

Fig. 75 - Return Air Sampling Tube Location
in Unit with Economizer

46

To install the return air sensor sampling tube:

Smoke Detector Test Magnet —

1. Remove the tube from its shipping location.
2. Open the unit end to access the return air sensor (located on right-- hand partition)
3. Orient the tube’s sampling holes into the return air
flow direction. For vertical application, position the
sampling holes on the bottom of the tube, facing into
the bottom return duct opening. For horizontal application, position the sampling holes on the side of the
tube, facing the unit’s end panel.
4. Insert the sampling tube into the return air sensor
module until the tube snaps into position.
5. Replace end panel or outside air hood.

Locate the magnet; it is shipped in the control box area.
Additional Application Data —
Refer to Catalog No. HKRNKA-- 1XA for discussions on
additional control features of these smoke detectors
including multiple unit coordination.

NOM.
V--- Ph--- Hz

IFM
TYPE

COMBUSTION
FAN MOTOR

POWER
EXHAUST

FLA

FLA

48HC*D17

460 ---3 ---60

575 ---3 ---60

48HC*D20

208/230 ---3 ---60

460 ---3 ---60

575 ---3 ---60

208/230 ---3 ---60

NO P.E.
FLA

LRA

MCA

FUSE or
HACR
BRKR

FLA

LRA

68.3

90.0

71

71.0

90.0

74

393

80.1

100.0

85

413

410

82.8

100.0

88

HIGH

75.8

100.0

430

80

419

87.6

100.0

93

STD

34.9

439

45.0

36

234

41.1

50.0

44

MED

246

36.3

45.0

38

243

42.5

50.0

45

255

HIGH

38.9

50.0

41

247

45.1

50.0

48

259

STD

26.2

30.0

27

184

31.0

40.0

33

192

26.2

30.0

27

184

31.0

40.0

33

192

HIGH

29

35

31

198

33.8

40

36

206

STD

75.7

100

79

440

87.5

100

93

460

80.5

100

85

449

92.3

100

98

469

HIGH

85.9

100

91

459

97.7

125

104

479

STD

36.6

45

38

245

42.8

50

46

257

39.2

50

41

249

45.4

50

49

261

HIGH

42

50

45

254

48.2

60

52

266

STD

26.2

30

27

186

31

40

33

194

29

35

31

200

33.8

40

36

208

HIGH

32.4

40

35

198

37.2

45

40

206

STD

88.7

100.0

93

544

100.5

125.0

107

564

94.1

110

100

554

105.9

125

113

574

107.6

125

114

628

119.4

150

128

648

48.6

60.0

51

277

54.8

60.0

58

289

51.4

60

54

282

57.6

70

61

294

57.4

70

61

319

63.6

80

68

331

35.5

45.0

37

204

40.3

50.0

43

212

38.9

50

41

202

43.7

50

47

210

HIGH

39.4

50

42

229

44.2

50

47

237

STD

117.4

150.0

121

584

129.2

175.0

135

604

MED

122.8

150

127

594

134.6

175

141

614

HIGH

135.5

175

142

668

147.3

175

156

688

STD

54.0

60.0

57

303

60.2

70.0

64

315

56.8

70

60

308

63

80

67

320

HIGH

62.8

80

67

345

69

80

74

357

STD

40.4

50.0

42

228

45.2

50.0

48

236

43.8

50

46

226

48.6

60

52

234

44.3

50

47

253

49.1

60

52

261

MED

MED

MED

MED

MED

MED

0.52

0.3

0.24

0.52

0.3

0.24

0.52

5.9

3.1

2.4

5.9

3.1

2.4

5.9

48HC*D24

STD
MED

0.3

3.1

HIGH
STD
575 ---3 ---60

48HC*D28

208/230 ---3 ---60

460 ---3 ---60

575 ---3 ---60

w/ P.E. (pwrd fr/ unit)

MCA

HIGH
460 ---3 ---60

NO C.O. or UNPWR C.O.

FUSE or
HACR
BRKR

STD
208/230 ---3 ---60

48HC

UNIT

Table 11 – Unit Wire/Fuse or HACR Breaker Sizing Data

MED

MED

MED

0.24

0.52

0.3

0.24

2.4

5.9

3.1

2.4

HIGH

NOTE: See page 49 for table legend and notes.

47

DISC. SIZE

DISC. SIZE

UNIT

Table 11 - Unit Wire/Fuse or HACR Breaker Sizing Data (cont)
NOM.
V--- Ph--- Hz

IFM
TYPE

COMBUSTION
FAN MOTOR

FLA

LRA

398

84.9

100.0

90

418

415

87.6

100.0

93

435

85

424

92.4

100.0

99

444

45.0

39

236

43.3

50.0

46

248

50.0

41

245

44.7

50.0

48

257

41.1

50.0

44

249

47.3

60.0

51

261

27.9

35.0

29

186

32.7

40.0

35

194

27.9

35.0

29

186

32.7

40.0

35

194

HIGH

30.7

40.0

33

200

35.5

45.0

38

208

STD

80.5

100

85

445

92.3

100

98

465

MED

85.3

100

90

454

97.1

110

104

474

HIGH

90.7

100

96

464

102.5

125

110

484

STD

38.8

50

41

247

45

50

48

259

41.4

50

44

251

47.6

60

51

263

HIGH

44.2

50

47

256

50.4

60

54

268

STD

27.9

35

29

188

32.7

40

35

196

30.7

40

33

202

35.5

45

38

210

HIGH

34.1

40

36

200

38.9

45

42

208

STD

93.5

110.0

99

549

105.3

125.0

112

569

98.9

125

105

559

110.7

125

119

579

HIGH

112.4

125

120

633

124.2

150

133

653

STD

50.8

60.0

54

279

57.0

70.0

61

291

53.6

60

57

284

59.8

70

64

296

HIGH

59.6

70

64

321

65.8

80

71

333

STD

37.2

45.0

39

206

42.0

50.0

45

214

40.6

50

43

204

45.4

50

49

212

HIGH

41.1

50

44

231

45.9

50

49

239

STD

122.2

150.0

127

589

134.0

175.0

140

609

127.6

175

133

599

139.4

175

147

619

140.3

175

148

673

152.1

200

161

693

56.2

70.0

59

305

62.4

80.0

66

317

59

70

62

310

65.2

80

70

322

HIGH

65

80

69

347

71.2

80

76

359

STD

42.1

50.0

44

230

46.9

60.0

50

238

45.5

60

48

228

50.3

60

54

236

46

60

49

255

50.8

60

54

263

MED

0.52

5.9

48HC*D17

STD
MED

0.3

3.1

HIGH
STD
575 ---3 ---60

48HC*D20

460 ---3 ---60

575 ---3 ---60

48HC*D24

208/230 ---3 ---60

460 ---3 ---60

575 ---3 ---60

208/230 ---3 ---60

MED

MED

MED

MED

MED

MED

MED

0.24

0.52

0.3

0.24

0.52

0.3

0.24

0.52

2.4

5.9

3.1

2.4

5.9

3.1

2.4

5.9

HIGH
48HC*D28

48HC

208/230 ---3 ---60

STD
460 ---3 ---60

575 ---3 ---60

w/ P.E. (pwrd fr/ unit)
FUSE or
HACR
BRKR

FLA

HIGH
460 ---3 ---60

NO P.E.
MCA

FLA

STD
208/230 ---3 ---60

w/ PWRD C.O.

POWER
EXHAUST

MED

MED

0.3

0.24

3.1

2.4

HIGH

FUSE or
HACR
BRKR

FLA

LRA

73.1

90.0

77

75.8

100.0

80

80.6

100.0

37.1
38.5

MCA

NOTE: See page 49 for table legend and notes.

48

DISC. SIZE

DISC. SIZE

Legend and Notes for Table 11

% Voltage Imbalance

= 100 x

max voltage deviation from average voltage
average voltage

Example: Supply voltage is 230-3-60
AB = 224 v
BC = 231 v
AC = 226 v

Average Voltage =
=

(224 + 231 + 226)
3

=

681
3

227

Determine maximum deviation from average voltage.
(AB) 227 – 224 = 3 v
(BC) 231 – 227 = 4 v
(AC) 227 – 226 = 1 v
Maximum deviation is 4 v.
Determine percent of voltage imbalance.
% Voltage Imbalance

= 100 x

4
227

= 1.76%

This amount of phase imbalance is satisfactory as it is below the
maximum allowable 2%.
IMPORTANT: If the supply voltage phase imbalance is more than
2%, contact your local electric utility company immediately.

49

48HC

LEGEND:
BRKR
--- Circuit breaker
CO
--- Convenience outlet
DISC
--- Disconnect
FLA
--- Full load amps
LRA
--- Locked rotor amps
MCA
--- Minimum circuit amps
PE
--- Power exhaust
PWRD CO
--- Powered convenient outlet
UNPWR CO
--- Unpowered convenient outlet
NOTES:
1. In compliance with NEC requirements for multimotor and
combination load equipment (refer to NEC Articles 430 and
440), the overcurrent protective device for the unit shall be
fuse or HACR breaker. Canadian units may be fuse or circuit
breaker.
2. Unbalanced 3-Phase Supply Voltage
Never operate a motor where a phase imbalance in supply
voltage is greater than 2%. Use the following formula to determine the percentage of voltage imbalance.

48HC

Economizer

2 Position Damper

Fig. 76 - EconoMi$ert IV Wiring

Step 13 — Adjust Factory--Installed Options

C10645

Two-- Position motorized outside air damper
EconoMi$er2 (without control/for external signal and
integrated barometric relief)
EconoMi$er IV (with control and integrated barometric
relief)
Power Exhaust
Differential dry-- bulb sensor (EconoMi$er IV)
Outdoor enthalpy sensor
Differential enthalpy sensor
CO2 sensor
DDC interface (PremierLink)
Louvered hail guard
Phase monitor control
Winter Start kit

EconoMi$er IV Occupancy Switch —
Refer to Fig. 76 for general EconoMi$er IV wiring.
External occupancy control is managed through a
connection on the Central Terminal Board.
If external occupancy control is desired, connect a time
clock or remotely controlled switch (closed for Occupied,
open for Unoccupied sequence) at terminals marked
OCCUPANCY on CTB. Remove or cut jumper JMP 2 to
complete the installation.

Step 14 — Install Accessories
Available accessories include:
Roof Curb
Thru-- base connection kit (must be installed before unit
is set on curb)
LP conversion kit
Manual outside air damper
High Altitude Gas kits
Low Ambient Controls
Thermostat / Sensors

Unit Without Economizer or
2 Position Damper

Refer to separate installation instructions for information
on installing these accessories.
Pre-- Start and Start-- Up
This completes the mechanical installation of the unit.
Refer to the unit’s Service and Maintenance manual for
detailed Pre-- Start and Start-- up instructions.

50

51

48HC

48HC
Copyright 2011 Carrier Corp. D 7310 W. Morris St. D Indianapolis, IN 46231

Printed in U.S.A.

Edition Date: 04/11

Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.

52

Catalog No: 48HC ---11SI
Replaces: 48HC--- 08SI



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