Carrier GT-G Series Installation, Operation & Maintenance Instructions Manual
®
Internal Auxiliary Electric Heat
Installation, Operation & Maintenance Instructions
Revision 1/99
Overview
The GT-G Series Auxiliary Electric Heat mounts internally on
any GT-G upflow (Figure 1) or downflow unit and mounts
directly on the blower outlet of all horizontal GT-G units
(Figure 6). Note the model compatibility Table 2. Horizontal
units are rated for zero clearance at the unit and 1" clearance
for first three feet of duct, vertical units rated for zero clearance
for both unit and duct. Downflow units can not be located
directly over a discharge register. The discharge plenum must
make a 90° turn after leaving the unit and be constructed from
non combustible material. The GT-G electric heat contains a
four stage relay control board which activates the elements
directly via an internally wired low voltage harness. Low
voltage signals (W1 and W2) are staged from the CXM or
DXM control of the GT-G unit. It should be noted that only
distributor model GT-G units are prewired for low voltage
control of the electric heat. Carrier Tech Support should
be contacted for use on all other models.
GT-G Series
Figure 1. Typical vertical unit installation.
Electric Heat Assembly
Air Coil
Auxiliary electric heat
power supply knockout
opposite air coil
Low Voltage control
harness is prewired
on all distributor class
Genesis
Vertical Upflow or Downflow Installation
1. Disconnect power to the unit
2. Remove blower access panels.
3. Clip wire-tie holding electric heat low voltage 3-wire
harness to discharge panel stiffener. Refer to Figure 1.
4. Remove blower mounting screws and then drop down
blower assembly as shown in Figure 2. Removal of blower
wires should not be necessary.
5. Install electric heat in discharge flange where blower
assembly has been removed using provided screws as
shown In Figure 3.
Figure 2. Blower removal.
Remove screws &
drop blower
Figure 3. GT-G electric heat mounting and blower
re-installation.
Locate electric heat assembly
on pins in discharge panel
and insert screws
Relocate blower in electric
heat assembly in same
manner
Note: For AGM electric heaters remove control box from
houseing by removing the control box cover and then removing
the four (4) screws (do not discard) that hold the control box to
the housing. Allow the control box to hang on the wire tie
located in the housing flange. After completing step 5 replace
the control box on the housing.
6. Re-install blower assembly, Figure 3, into electric heat
L2
L1
Conduit
assembly using blower mounting screws. Check blower
wiring for proper wiring connections.
7. Route the low voltage harness through the provided ‘pie’
bushing and plug into electric heat control board connector
P2 as shown in Figure 4.
8. Install power conduit, Figure 5, through unit corner post
knockout and attach conduit directly to the electric heat
control box.
Horizontal Installation
1. Disconnect power to the unit
2. Remove blower access panels.
3. Clip wire-tie holding electric heat low voltage 3-wire
harness to discharge panel stiffener.
4. Remove blower discharge flange screws and remove the
two flanges and discard them but save the screws.
5. Install electric heat in discharge flange mounting where
discharge flange had been removed using the old screws.
6. Route the low voltage harness through unit discharge panel
knockout and seal penetration 'air tight'.
7. Then route the harness through the provided ‘pie’ bushing
in the electric heat control box and plug into electric heat
control board connector P2 as shown.
8. Install power conduit and attach directly to the electric heat
control box.
Wiring and Setup (all models)
Figure 4. Low Voltage Harness Connection
Figure 6. Typical Horizontal Installation
Remove discharge flange and
replace with horizontal auxiliary
electric heat
Optional disconnect
refer to local codes
Figure 7a. Power Wiring, Dual Circuits, 12, 15, 20kw
Locate electric heat
harness in air handler
and route through
provided bushing
P2
P1
1234
Connect 5 pin low
voltage connector
to board
Figure 5. Power Conduit And Wire Routing
Electric Heat Assembly
Auxiliary electric heat power
supply knockout opposite air coil
Route conduit thru cabinet and
connect to electric heat control
box. Seal to eliminate air leaks on
cabinet exterior.
ON
OFF
ON
OFF
Disconnect (optional
refer to local code)
P2
Figure 7b. Power
Wiring, Single Circuit,
12, 15, 20kw
In 12, 15 and 20 kW units, optional
single power circuitb is employed to
reduce the number of wires needed.
L2
L4
OFF
L3
L2
OFF
L1
L1
In 12, 15 and 20 kW units
two power circuits are
employed to reduce wires
size and cost of breakers
P1
1234
L4
ON
OFF
L3
L2
ON
OFF
L1
Conduit
Figure 7c. Power Wiring,
4, 5, 8, And 10kw
Page 2
Conduit
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