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FURNACE OPERATING SEQUENCE
A. Gas Furnace
1. On a call for heat, the thermostat contacts
close, which applies 24 volts to the “W”
terminal.
2. The combustion blower motor energizes.
After the motor begins to rotate, the
centrifugal switch, which is located in the
motor end cap, closes.
3. A thirty (30) second pre-purge period
begins, during which the ignition control will
initiate an internal safety start check.
4. Upon passing the safety check, the control
begins a fifteen (15) second ignitor warm-
up period. During this period, the ignitor will
warm to the ignition temperature.
5. The control then applies 24 volts to the gas
valve.
6. The ignitor ignites the gas, and the
presence of flame will be detected using
flame rectification principles.
7. The flame must be detected within a timed
trial ignition period. If the flame is detected,
then the ignitor is de-energized. The gas
valve will remain open until the call for heat
from the thermostat is completed.
Conversely, if the flame is not detected,
then the control will close the gas valve at
the end of the timed trial ignition period. The
control will then attempt ignition two (2)
more times before locking out.
8. The circulating air blower will energize
thereafter, when the temperature fan
switch closes.
9. When the thermostat is satisfied, the “W”
terminal is de-energized.
10. The gas valve circuit will be de-energized,
and the gas valve will close.
11. The circulating air blower will de-energize,
when the temperature fan switch opens.
The control will close the gas valve, if the
presence of flame is not or no longer detected.
The control will attempt to re-ignite the gas twice
before locking out. Once in lock-out, the control
can be reset by interrupting the 24 volt power.
This can be easily accomplished by setting the
thermostat below room temperature for at least
forty five (45) seconds, and then returning it to
the desired setting.
If adjusting the thermostat does not reset the
ignition control, turn off the power to the appliance
for forty five (45) seconds, and then turn it back
on.
NOTE: If the gas control has been replaced or
serviced, lighting may not be satisfactory until
air has been purged from the gas line or the gas
input and combustion air have been adjusted.
B. Oil Furnace - Honeywell R7184 Control
1.
When a call for heat is initiated, there is a
2-6 second delay while the control
performs a safe start check.
2.
The ignition and motor are turned on and
a flame should be established within the
15-second lockout time.
3.
If flame is not sensed within the 15-second
lockout time, the control shuts down on
safety lockout and must be manually reset.
If control locks out three times in a row, the
control enters restricted lockout. To reset,
hold down the reset button for 30 seconds
until the LED flashes twice.
4.
Once flame is established, the ignition
remains on 10 seconds to ensure flame
stability. It then turns off. (interrupted
ignition)
5.
The circulating air blower will energize
thereafter, the temperature fan switch
closes.
6.
The furnace runs until the call for heat is
satisfied. Burner is shut down.
7.
The circulating air blower will de-energize,
when the temperature fan switch opens.
ADJUSTING HEAT DISTRIBUTION
1. Set the room thermostat for the desired
room temperature.
2. Balance the heat distribution by adjusting
the register openings.
Содержание CMF 100-PG
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