Part 2 Service and Maintenance
9
minimum rated gas pressure is being supplied to the
burner during regulator adjustments, and NEVER
bottom out regulator screw.
If the pressure regulator fails to maintain a constant
manifold gas pressure within ±0.1" W.C., and it is confirmed
that the inlet gas pressure to the Combination Gas Valve is
a steady 14.0" W.C. maximum during standby, and a
steady 6.0" W.C. minimum with the flame on, the regulator
portion of the gas valve is defective and the entire gas
valve must be replaced.
CAUTION: If the Combination Gas Valve has been
moved or replaced, perform test for leaks with the
burner running.
CAUTION: If leakage through the gas valve occurs
on standby, as evidenced by the presence of any flame,
the entire gas valve needs to be replaced.
___________________________
XIV - Electronic Control
Operation - Power Up/Standby: Upon applying power
(24 volts) to 24VAC, the control will reset, perform a self
check routine, initiate full time flame sensing, flash the
diagnostic LED for up to four seconds, and enter the
thermostat scan state.
Heat Mode: when a call for heat is received from the
thermostat, the control will check the internal blower motor
interlock switch for normally open contracts. The combustion
blower is then energized and once the internal blower motor
interlock switch contacts close, a pre-purge delay begins.
Following the pre-purge period the gas valve is energized and
spark will commence for the trial for ignition period.
When flame is detected during the trial for ignition, spark
should shutoff immediately while the gas valve and combustion
blower remain energized. The thermostat, internal blower motor
interlock switch, and main burner flame are constantly
monitored. When the thermostat is satisfied and the call for
heat ends, the main valve is de-energized immediately, the con-
trol senses the loss of flame signal and initiates an (optional)
post-purge period before de-energizing the combustion blower.
Failure to Light - Lockout: Should the main burner fail to
light, or flame is not detected during the trial for ignition period,
the control will go into lockout. The valve will be turned off
immediately, and the combustion blower will be turned off fol-
lowing an optional post purge period.
WARNING: Explosion hazard. Can cause serious injury
or death. This device can malfunction if it gets wet. Never
try to use a device that has been wet or submerged.
___________________________
Maintenance
Keep the area around the burner clear and free of combustible
materials, gasoline and other flammable liquids or vapors. Do
not obstruct burner air inlet or ventilation air.
The motor features permanently lubricated ball bearings
and requires no routine oiling or maintenance.
IMPORTANT: Check the burner flame periodically. A proper
NATURAL gas flame will appear blue at the burner face with
orange and yellow tips. A proper PROPANE gas flame will
appear blue at the burner face with yellow tips. If the flame is
too rich, it will appear billowy and yellow with hazy tips. If too
lean, it will appear short and all blue. If the flame does not
appear proper, CONTACT A QUALIFIED SERVICE
TECHNICIAN FOR CLEANING, READJUSTMENT AND/OR
REPAIR.
WARNING: If any flame is observed when the burner is
on standby, or if the ignition spark or gas valve operator is
heard to come on before the motor reaches operating
speed, immediately turn off the Main Manual Shut-off Valve
and power to the burner. A dangerous condition has devel-
oped and must be corrected. CONTACT A QUALIFIED
SERVICE TECHNICIAN FOR CLEANING, RE-ADJUSTMENT
AND/OR REPAIR.
WARNING: If PROPANE gas is used and the burner is
located in a basement, crawl space or confining space,
contact your gas supplier about installing a GAS LEAK
warning device. PROPANE gas is heavier than air and can
settle in low areas or confined spaces. This would create a
dangerous condition and cause an explosion or fire. If you
suspect a gas leak, follow instructions on front cover of
this manual.
___________________________
Maintenance
Midco International Inc. - Chicago IL - www.midcointernational.com
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