Inspection and Maintenance
5-6
750-392
CBEX-DE
A 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 the conditions should be checked on a scheduled basis.
The following tests should be used to test the complete safeguard system. If the sequence of events is not as
described, then a problem may exist. Contact your local Cleaver-Brooks authorized representative for assistance.
5.6.1 — 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. The ignition spark can be viewed through the sight port in the rear door. Since there is no flame to
be detected, the program relay will signal the condition. The ignition circuit will de-energize and 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. Reopen the gas pilot shutoff cock and re-establish main fuel
supply.
5.6.2 — 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) de-energize 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.
5.6.3 — Checking Loss of Flame
With the burner in normal operation, shut off the main burner fuel supply to extinguish main flame.
The fuel valve(s) will be de-energized and the relay will signal the condition within 4 seconds. The control will
then 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.
When replacing a control, be sure to lock out the main power supply switch since the control is “hot” even though
the burner switch is off. Failure to follow these instructions could result in serious injury or death.
!
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