ECR International Utica Boilers UB90-50 Installation, Operation & Maintenance Manual page 39

DETAILED SEQUENCE OF OPERATION
End Of Normal Sequence Of Operation
Thermostat ends call for heat.
Gas valve and circulator pump are
de-energized, valve and flame lights go out.
Blower runs for 30 seconds post purge,
purge light is on.
Blower is de-energized after 30 seconds,
purge light shuts off.
Boiler stand by for next call for heat.
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