ICP 9MAC/E series, Руководство по устранению неисправностей

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range input (low range input is an input rate less than or equal
to 51% of full rate, 45% of full rate on the 5T-060 model), the
furnace control will turn the blower ON or switch to the
modulating heat airflow, energize the PSR relay to open the NC
contact, and slowly decrease the inducer motor speed to the
desired inducer RPM.
Switching from Intermediate-Heat to a Medium Range
Input -
If the furnace control CPU switches from intermediate-
heat to a different medium range input (medium range input is
an input rate between 52% and 71% of full rate, 46% and 71%
of full rate on the 5T-060 model), the furnace control CPU will
turn the blower ON or switch to the modulating heat airflow,
and continue to maintain the inducer motor speed or change it
further if required.
Switching from Intermediate-Heat to a High Range Input -
If the furnace control CPU switches from Intermediate-heat to a
high range input (high range input is an input rate greater than
or equal to 72% of full rate), the furnace control CPU will turn
the blower ON or switch to the modulating heat airflow, and
increase the inducer motor speed to the desired inducer motor
RPM.
Switching from Low Range Input to Maximum-Heat -
If the
furnace control CPU switches from a low range input to
maximum-heat, the furnace control CPU de-energize the PSR
relay to close the NC contact and slowly increase the inducer
motor speed until the medium pressure switch MPS closes.
When the medium pressure switch MPS closes the inducer
motor RPM is noted by the furnace control CPU. The RPM is
used to evaluate vent system resistance. This evaluation is then
used to determine the required RPM necessary to operate the
inducer motor at maximum-heat. The blower motor BLWM
will transition to maximum-heat airflow five seconds after the
furnace control CPU switches from a low range input to
maximum-heat. As the inducer RPM increases the high
pressure switch HPS should close.
Switching from Medium Range Input to Maximum-Heat -
If the furnace control CPU switches from a medium range input
to maximum-heat, the furnace control CPU will increase the
inducer motor speed to the maximum-heat inducer motor RPM.
The blower motor BLWM will transition to maximum-heat
airflow five seconds after the furnace control CPU switches
from a medium range input to maximum-heat. As the inducer
RPM increases the high pressure switch HPS should close.
8. Blower-Off Delay
- When the thermostat is satisfied, the
R to W circuit is opened, de-energizing the gas valve GV,
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 minimum-heat airflow or transition to minimum-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.
TWO-STAGE THERMOSTAT AND TWO-STAGE
MINIMUM/MAXIMUM HEATING
Note:
In this mode the minimum-heat only switch SW1-2 must be
ON to select the minimum-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 maximum-heat operation,
regardless of the setting of the minimum-heat only switch.
The furnace will start up in either intermediate-, or maximum-heat.
The furnace will operate in minimum-heat after starting and
operating for 45 seconds at intermediate-heat before transitioning to
minimum-heat.
The wall thermostat "calls for heat", closing the R to W1 circuit for
minimum-heat or closing the R to W1-and-W2 circuits for
maximum-heat. The furnace control performs a self-check, and
verifies the low, medium, and high pressure switch contacts LPS,
MPS, and HPS are open, then de-energizes the PSR relay to close the
NC contact.
The start up and shut down functions and delays described above
apply to the 2-stage minimum/maximum heating mode as well,
except for switching from maximum- to minimum-heat.
1. Switching from Maximum- to Minimum-Heat
- If the
thermostat R to W2 circuit opens, and the R to W1 circuit
remains closed, the furnace control CPU will gradually decrease
the inducer motor speed to the required intermediate-heat RPM.
When the inducer motor IDM reduces pressure sufficiently, the
high pressure switch HPS will open and the gas rate will be
changed to intermediate-heat. The gas valve solenoid GV (pin
PL17-5) will remain energized as long as the low pressure
switch LPS remains closed. When the inducer motor speed gets
within 15% of the required intermediate-heat RPM the furnace
control CPU will start a 5 second blower airflow change delay.
After the 5 second blower airflow change delay is completed the
blower airflow will transition to minimum-heat airflow. At this
point the furnace control CPU will energize the PSR relay to
open the NC contact and slowly decrease the inducer motor
speed to the required minimum-heat RPM. When the PSR
relay is energized and the NC contact opens the furnace control
CPU will reduce the gas rate to minimum-heat.
TWO-STAGE THERMOSTAT AND TWO-STAGE
INTERMEDIATE/MAXIMUM HEATING
Note:
In this mode the intermediate-heat only switch SW4-2 must
be ON to select the intermediate-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 maximum-heat
operation, regardless of the setting of the intermediate-heat only
switch.
The wall thermostat "calls for heat", closing the R to W1 circuit for
intermediate-heat or closing the R to W1-and-W2 circuits for
maximum-heat. The furnace control performs a self-check, and
verifies the low, medium, and high pressure switch contacts LPS,
MPS, and HPS are open, then de-energizes the PSR relay to close the
NC contact.
The start up and shut down functions and delays described above
apply to the 2-stage intermediate/maximum heating mode as well,
except for switching from maximum- to intermediate-heat.
1. Switching from Maximum- to Intermediate-Heat
– If the
thermostat R to W2 circuit opens, and the R to W1 circuit
remains closed, the furnace control CPU will gradually decrease
the inducer motor speed to the required intermediate-heat RPM.
When the inducer motor IDM reduces pressure sufficiently, the
high pressure switch HPS will open and the gas rate will be
changed to intermediate-heat. When the inducer motor speed
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