ICP 8MPT Installation Insrtuctions page 23

2. Move large hole plug from right to left J-Box location.
3. Clip wire tie holding J-Box wires if needed.
4. Move J-Box to alternate location and attach using two
screws removed from left side location.
5. Position all wires away from hot surfaces, sharp edges, and
moving parts. Do not pinch J-Box wires or other wires when
reinstalling burner compartment door.
Thermostat
Heating
The two-stage furnace control board wilt operate with either a
single stage or a two-stage heating thermostat and wilt provide
two-stage heating operation.
For single-stage thermostat installations, the R and W wires
from the thermostat connect to the R and Wl connections on the
furnace control board.
Note: The TT (Thermostat Type) SW1 DIP switch # 3 should be in
the off position for the furnace to operate properly with a single-
stage thermostat. Failure to change DIP switch with single-stage
thermostat wilt result in Low Heat operation ONLY. (See
Figure 21 and wiring diagram)
During operation, the furnace will operate on tow Heat for up to12
minutes. If the heat request exists for more than 12 minutes, the
furnace wilt automatically shift to the high Heat mode for the re-
maining duration of the heating cycle.
For two-stage thermostat installations, the R, Wl and W2 wires
from the thermostat connect to the R, Wl and W2 connections on
the furnace control board. Set TT SW1 DIP switch #3 to ON posi-
tion. During operation, the furnace will shift from Low Heat to High
Heat as requested by the thermostat. (See Figure 19, Figure 20
and wiring diagram)
Heat anticipator setting will need to be measured if 24VAC humidi-
fier is installed. Measure current in series from R to Wl at the ther-
mostat. Be sure 24VAC humidifier is wired up to control. Allow
furnace to operate for two minutes before recording the AC am-
perage reading. Set anticipator on thermostat to recorded value.
Thermostat location has an important effect on the operation of
the furnace. Follow instructions included with thermostat for cor-
rect mounting and wiring.
Low voltage connections to furnace must be made on terminal
board to furnace control board. (See Figure 19 and Figure 20)
Cooling
*8MPT
If cooling is used, the Y and G from the thermostat must be con-
nected to the control board Y/Y2 and G to energize cooling blower
speed.
NOTE: MPT models are not two-stage cooling compatible.
*8MPV
If single-stage cooling is used, the Y and G from the thermostat
must be connected to the control board Y/Y2 and G to energize
cooling blower speed.
If two-stage cooling is used, the Y1, Y2, G off the thermostat must
be connected to Y1 of the tap select interface board for Low Cool-
ing, Y/Y2 of the furnace control board for High Cooling and G of the
furnace control board for continuous fan speed.
Optional Equipment
All wiring from furnace to optional equipment MUST conform to
local codes or, in the absence of local codes with the latest edition
of The National Electric Code, NFPA 70 and/or The Canadian
Electric Code CSA C22.1. Install wiring in accordance with
manufacturer's instructions. The wiring MUST have a minimum
temperature rating of 105° C.
Humidifier/Electronic Air Cleaner
The furnace is wired for humidifier and/or electronic air cleaner
connection.
HUMIDIFIER - The HUM (24V) terminal is energized when
the tow pressure switch closes on a call for heat. The HUM
(115V) is energized when the inducer is energized.
ELECTRONICAIR CLEANER - EAC is energized when there
is a blower speed call, except it is NOT energized when blower
operates in the hard-wired continuous fan mode.
REDUCED FURNACE LIFE HAZARD
Failure to follow caution instructions may result in
reduced furnace life.
Do NOT exceed 115V/1.0 amp. maximum current
load for both the EAC terminal and the HUM
terminal combined.
Furnace Control Board
The furnace control board has a fixed blower ON delay of 30
seconds for High Heat calls and 45 seconds for Low Heat calls.
The blower OFF timing is factory preset at 140 seconds. If desired,
the fan OFF delay can be reset to obtain the longest delay times
while still maintaining comfort levels. See "Furnace Wiring
Diagram".
Dehumidification- Variable Speed ONLY (*8MPV)
The furnace control board has a dehumidification feature which
reduces cooling airflow by 20% when the DEHUM terminal
[1/4"
(6.4mm) male quick connect] is energized by 24VAC and there is a
cooling call. DEHUM may be operated by a thermostat dehumidify
(24VAC for dehumidify) command or a dehumidistat (switch
closes on call for dehumidification) with one terminal connected to
(Y1 for two-stage cooling or Y/Y2 for single-speed cooling
applications) and the other terminal connected to DEHUM
23
Specifications are subject to change without notice
441 01 202301