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BOILER SEQUENCE OF OPERATION
A call for heat by the thermostat energizes the L8124C control which in turn energizes the primary control to turn on
the burner. The burner will operate in the following sequence: Prepurge for the fi rst 10 seconds; fi re until the thermo-
stat is satisfi ed or the limit setting on the high limit is reached; post-purge for the last 10 seconds. The circulator will
also operate when the thermostat calls for heat if the boiler water temperature is up to the setting of the low limit in the
L8124C control. If boiler water temperature is below the low limit setting the burner will operate but the circulator will
not, giving preference to the domestic hot water demand.
If the thermostat is not satisfi ed when the high limit is reached the burner will stop but the circulator will continue to
operate until the thermostat is satisfi ed. Any time the boiler water temperature drops below the setting of the low limit
the burner will be energized in order to maintain domestic water temperature.
On burner start, if the cad cell does not see fl ame within approximately 15 seconds, primary control will shut burner
down and enter into a recycle mode, after 60 seconds burner will restart and repeat trial for ignition. If after three
(3) trials for ignition, fl ame is not detected, control will enter into restricted mode and must be reset manually before
burner can be restarted.
Figure 23D: Wiring Diagram, Water with Rear Tankless Heater for Beckett Burners