Optional Equipment - International comfort products C9MVX Installation Instructions Manual

unit maximum amps stated on the rating plate. Add the full load
amps for potential field−installed accessories such as electronic
air cleaners and humidifiers that would receive power from the
furnace control board. The furnace control board is rated for a
maximum of 1.0 amps combined for EAC and HUM. Consult NEC
or local codes for proper wire and circuit sizing.
Junction Box (J-Box) Relocation
The J−Box is installed on left side of casing. An alternate J−Box
location on right side can be used.
1. Remove bag containing two hole plugs and two self tapping
screws from loose parts bag in blower compartment.
2. Remove two screws holding J−Box to casing.
3. Install large hole plug from loose furnace accessory bag into
the left J−Box location.
4. Clip wire tie holding J−Box wires.
5. Move J−Box to alternate location and attach using two self
tapping screws from bag.
6. Apply two hole plugs from bag at left J−Box location.
Thermostat
Heating
The two−stage furnace control board will operate with either a
single stage or a two−stage heating thermostat and will provide
two−stage heating operation.
For single−stage thermostat installations, the R and W wires from
the thermostat connect to the R and W1 connections on the
furnace control board. (See Figure 34 and wiring diagram)
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 will result in Low Heat operation ONLY.
During operation, the furnace will operate on Low Heat for up to12
minutes. If the heat request exists for more than 12 minutes, the
furnace will automatically shift to the High Heat mode for the
remaining duration of the heating cycle.
For two−stage thermostat installations, the R, W1 and W2 wires
from the thermostat connect to the R, W1 and W2 connections on
the furnace control board. Set TT SW1 DIP switch #3 to ON
position. During operation, the furnace will shift from Low Heat to
High Heat as requested by the thermostat. (See Figure 34 and
wiring diagram)
When using a non−electronic thermostat, the thermostat heat
anticipator must be set to match the amp draw of the electrical
components in R − W1 circuit. Accurate amp draw readings can be
obtained at thermostat subbase terminals R to W1. For an
electronic thermostat, set cycle rate for 3 cycles per hour.
Measure heat anticipator current in series from R to W1 at the
thermostat. If 24VAC humidifier is wired up to control, humidifier
must be energized. Allow furnace to operate for two minutes before
recording the AC amperage 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 correct
mounting and wiring.
Low voltage connections to furnace must be made on terminal
board to furnace control board. (See Figure 35)
38
Cooling
*9MPT
If 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.
NOTE: MPT models are not two−stage cooling compatible.
*9MPV, *9MVX
If single−speed 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 of the thermostat must
be connected to Y1 of tap select interface board for low cooling,
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, ANSI 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
low pressure switch closes on a call for heat. The HUM (115V)
is energized when the inducer is energized.
ELECTRONIC AIR CLEANER − EAC terminal 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 this caution 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 (*9MPV, *9MVX)
The furnace control board has a dehumidification feature which
reduces cooling airflow by 20% when the DEHUM terminal (
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.
Specifications are subject to change without notice.
CAUTION
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