Inspection and Maintenance
7-6
750-96 (revised 2010)
Model CB Packaged Boiler Manual
When replacing a control, be sure to open the main power supply switch since the control is “hot” even though the
burner switch is off. Make sure the connecting contacts on the control and its base are not bent out of position.
A periodic safety check procedure should be established to test the complete safeguard system at least once a
month or more often. Tests should verify safety shutdown and a safety lockout upon failure to ignite the pilot, upon
failure to ignite the main flame, and upon loss of flame. Each of these conditions should be checked on a sched-
uled basis. These tests will also verify fuel valve tightness.
7.6.1 — Checking Pilot Flame Failure
Close the gas pilot shutoff cock. Also shut off the main fuel supply. Turn the burner switch “on.”
The pilot ignition circuit will be energized at the end of the pre-purge period. There should be an ignition spark but
no flame. Since there is no flame to be detected, the program relay will signal this condition. The ignition circuit
will be de-energized and the control will lockout on a safety shutdown. The flame failure light (and optional alarm)
will be activated. The blower motor will run through the post-purge and stop.
Turn the burner switch off. Reset the safety switch. Reopen the gas pilot shutoff cock and re-establish main fuel
supply.
7.6.2 — Checking Failure to Light Main Flame
Leave the gas pilot shutoff cock open. Shut off the main burner fuel supply. Turn the burner switch on. the pilot will
light upon completion of the pre-purge period. The main fuel valve(s) will be energized, but there should be no main
flame.
The fuel valve(s) will be de-energized within 4 seconds after the main burner ignition trial ends. The control will lock
out on a safety shutdown. The flame failure light (and optional alarm) will be activated. The blower motor will run
through the post-purge and stop.
Turn the burner switch off. Reset the safety switch. Re-establish main fuel supply.
7.6.3 — Checking Loss of Flame
With the burner in normal operation, shut off the main burner fuel supply to extinguish the main flame.
The fuel valve(s) will be de-energized and the relay will signal this condition within 4 seconds. The control will then
lockout on a safety shutdown. The flame failure light (and optional alarm) will be activated. The blower motor will
run through the post-purge and stop.
Turn the burner switch off. Reset the safety switch. Re-establish main fuel supply.
The flame detector lens should be cleaned as often as operating conditions demand. Use a soft cloth moistened
with detergent.
Courtesy of: C3 Surplus LLC
Surplus Industrial Superstore
305-428-2777
https://www.c3surplus.com
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