ICP F9MVE Series, Service And Technical Support Manual

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SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: (F/G)9MVE
Specifications subject to change without notice.
31 440 04 4801 04
valve GV − M, stopping gas flow to the burners, and
de − energizing the humidifier terminal HUM. The
inducer motor IDM will remain energized for a
15 − second post − purge period. The blower motor
BLWM and air cleaner terminal EAC − 1 will remain
energized at low − heat airflow or transition to low − heat
airflow for 90, 120, 150, or 180 seconds (depending
on selection at blower − OFF delay switches). The
furnace control CPU is factory − set for a 120 − second
blower − OFF delay.
2. Two − Stage Thermostat and Two − Stage Heating
See Figure 18 − Figure 21 for thermostat connections.
NOTE : In this mode the low − heat only switch SW1 − 2 must be
ON to select the low − heat only operation mode in response to
closing the thermostat R − to − W1 circuit. Closing the thermostat
R − to − W1 − and − W2 circuits always causes high − heat operation,
regardless of the setting of the low − heat only switch.
The wall thermostat “calls for heat”, closing the R − to − W1 circuit
for low − heat or closing the R − to − W1 − and − W2 circuits for
high − heat. The furnace control performs a self − check, verifies
the low − heat and high − heat pressure switch contacts LPS and
HPS are open, and starts the inducer motor IDM in
high − speed.
The start up and shut down functions and delays described in
item 1. above apply to the 2 − stage heating mode as well,
except for switching from low − to high − Heat and vice versa.
a. Switching from Low − to High − Heat − If the
thermostat R − to − W1 circuit is closed and the
R − to − W2 circuit closes, the furnace control CPU will
switch the inducer motor IDM speed from low to high.
The high − heat pressure switch relay HPSR is
de − energized to close the NC contact. When
sufficient pressure is available the high − heat pressure
switch HPS closes, and the high − heat gas valve
solenoid GV − HI is energized. The blower motor
BLWM will transition to high − heat airflow five seconds
after the R − to − W2 circuit closes.
b. Switching from High − to Low − Heat − If the
thermostat R − to − W2 circuit opens, and the R − to − W1
circuit remains closed, the furnace control CPU will
switch the inducer motor IDM speed from high to low.
The high − heat pressure switch relay HPSR is
energized to open the NC contact and de − energize
the high − heat gas valve solenoid GV − HI. When the
inducer motor IDM reduces pressure sufficiently, the
high − heat pressure switch HPS will open. The gas
valve solenoid GV − M will remain energized as long
as the low − heat pressure switch LPS remains closed.
The blower motor BLWM will transition to low − heat
airflow five seconds after the R − to − W2 circuit opens.
3. Cooling mode
The thermostat “calls for cooling”.
a.
Single − Speed Cooling −
See Figure 18 and Figure 20 for thermostat
connections
The thermostat closes the R − to − G − and − Y circuits.
The R − to − Y circuit starts the outdoor unit, and the
R − to − G − and − Y/Y2 circuits start the furnace blower
motor BLWM on cooling airflow. Cooling airflow is
based on the A/C selection shown in Table 5 . The
electronic air cleaner terminal EAC − 1 is energized
with 115 vac when the blower motor BLWM is
operating.
When the thermostat is satisfied, the R − to − G − and − Y
circuits are opened. The outdoor unit will stop, and
the furnace blower motor BLWM will continue
operating at cooling airflow for an additional 90
seconds. Jumper Y/Y2 to DHUM to reduce the
cooling off − delay to 5 seconds. (See Figure 4 )
b. Two − Stage Thermostat and Two − Speed Cooling
See Figure 19 and Figure 21 for thermostat
connections
The thermostat closes the R − to − G − and − Y1 circuits for
low − cooling or closes the R − to − G − and − Y1 − and − Y2 circuits for
high − cooling. The R − to − Y1 circuit starts the outdoor unit on
low − cooling speed, and the R − to − G − and − Y1 circuit starts the
furnace blower motor BLWM at low − cooling airflow which is the
CF (continuous fan) selection as shown in Figure 5 . The
R − to − Y1 − and − Y2 circuits start the outdoor unit on high − cooling
speed, and the R − to − G − and − Y/Y2 circuits start the furnace
blower motor BLWM at high − cooling airflow. High − cooling
airflow is based on the A/C (air conditioning) selection shown in
Figure 5 .
The electronic air cleaner terminal EAC − 1 is energized with 115
vac whenever the blower motor BLWM is operating.
When the thermostat is satisfied, the R − to − G − and − Y1 or R − to −
G − and − Y1 − and − Y2 circuits are opened. The outdoor unit
stops, and the furnace blower BLWM and electronic air cleaner
terminal EAC − 1 will remain energized for an additional 90
seconds. Jumper Y1 to DHUM to reduce the cooling off − delay
to 5 seconds. (See Figure 16 )
4. Dehumidfy Mode
See Figure 18 − Figure 24 for thermostat connections.
The H output on the humidify sensing thermostat should
be connected to the furnace control thermostat terminal
DHUM. When there is a dehumidify demand, the DHUM
input is activated, which means 24 vac signal is removed
from the DHUM input terminal. In other words, the DHUM
input logic is reversed. The DHUM input is turned ON
when no dehumidify demand exists.
Activation/Deactivation
Once 24 vac is detected by the furnace control on the
DHUM input, the furnace control operates in dehumidify
mode. If the DHUM input is low for more than 48 hours,
the furnace control reverts back to non − dehumidify
mode.
The cooling operation described in Item 3, Cooling
mode. above also applies to operation with a humidity
sensing thermostat. The exceptions are listed below:
a.
Low Cooling − When the R − to − G − and − Y1 circuit is
closed and there is a demand for dehumidification,
the low cooling airflow demand is reduced by 10
percent.
b. High − Cooling − When the R − to − G − and − Y/Y2 circuit is
closed and there is a demand for dehumidification,
the high cooling airflow demand is reduced by 10
percent.
c. Cooling off − delay − When the “call for cooling” is
satisfied and there is a demand for dehumidification,
the cooling blower − off delay is decreased from 90
seconds to 5 seconds.
5. Continuous Blower Mode
When the R − to − G circuit is closed by the thermostat, the
blower motor BLWM will operate at continuous blower
airflow. Continuous blower airflow selection is initially
based on the CF (continuous fan) selection shown in
Figure 5 . Factory default is shown in Figure 5 . Terminal
EAC − 1 is energized as long as the blower motor BLWM
is energized.
During the call for heat, the furnace control CPU will keep
the blower motor BLWM to continuous blower airflow.
The blower motor BLWM will remain ON until the main
burners ignite then shut OFF and remain OFF for the
blower − ON delay (45 seconds in low − heat, and 25
seconds in high − heat), allowing the furnace heat
exchangers to heat up more quickly, then restarts at the
end of the blower − ON delay period at low − heat or
high − heat airflow, respectively.