Abnormal Heat Cycle
Functions
present after the flame proving period, the control de-energizes the gas
valve and proceeds with ignition re-tries as specified in “Abnormal Heat
Cycle, Ignition Retry”. If flame is present, the control proceeds to the fan/
blower on delay.
4) Fan/Blower On Delay
- The control waits for 30 seconds from the time
the gas valve opened and then energizes the fan/blower motor. The gas
valve and venter motor remain energized. The control proceeds to steady
heat mode.
5) Steady Heat
- Control inputs are continuously monitored to ensure limit
and pressure switches are closed, flame is established, and the thermostat
call for heat remains. When the thermostat call for heat is removed, the
control de-energizes the gas valve and begins post-purge and fan/blower
off delay timing.
6) Post Purge
- The venter motor output remains on for a 45-second post-
purge period after the thermostat is satisfied.
7) Fan/Blower Off Delay
- The fan/blower motor is de-energized after a
blower off delay as selected by the dip switches. Timing begins when the
thermostat is satisfied. Delay times are as follows:
SW1 SW2 Time
OFF OFF 120 seconds (default when shipped)
OFF ON
90 seconds
ON
OFF 160 seconds
ON
ON
45 seconds
Interrupted Thermostat Call for Heat
- If the thermostat demand for heat
is removed before the flame is recognized, the control will run the venter
motor for the post purge period and de-energize all outputs.
If the thermostat demand for heat is removed after successful ignition, the
control will de-energize the gas valve, run the venter motor through post
purge, and run the fan/blower motor on heat speed for the selected delay
off time.
Ignition Retry
- If flame is not established on the first trial for ignition period,
the control de-energizes the gas valve and the venter motor remains ener-
gized for an inter-purge period of 10 seconds. The spark and gas valve are
then re-energized, and the control initiates another trial for ignition.
If flame is not established on the second trial for ignition, the control de-
energizes the gas valve, energizes the fan/blower motor on heat speed,
and venter motor remains energized. The fan/blower motor is shut off after
the longest selectable fan delay time (160 seconds). When the fan/blower
motor de-energizes, the spark and gas valve are re-energized and the con-
trol initiates another trial for ignition. (This fan delay is self-healing feature
for an open auxiliary limit switch).
If flame is not established on the third trial for ignition period, the control
de-energizes the gas valve, and the venter motor remains energized for
an inter-purge period of 10 seconds. The control then re-energizes the gas
valve and spark and initiates another trial for ignition.
If flame is not established on the fourth trial for ignition (initial try plus 3 re-
tries), the control de-energizes the gas valve and goes into lockout. The
control goes to one flash on the green LED to indicate ignition failure lock
-
out.
Limit Switch Operation
- The limit switch is ignored unless a call for heat
is present (W energized). If the limit switch is open and a call for heat is
Form I-UEAS, P/N 221232 R6, Page 35
