Lochinvar Power-fin 502 Service Manual page 10

1
Service
Sequence of operation
Table 1A_(continued from previous page) Sequence of Operation - Space Heating and DHW
O O P P E E R R A A T T I I O O N N
9. If the DHW thermostat remains on for more than
30 minutes, and the space heating call for heat is also on,
then the control will turn on the boiler pump, turn off the
DHW pump after 2 seconds, and resume firing based on the
space heating set point. As long as both the space heating
and DHW calls for heat remain active, the control will switch
back and forth between the two modes until one of them is
satisfied.
10. Once both calls for heat are satisfied, the control will turn
off the burner. The blower will remain on for the
30 second postpurge cycle. Any pumps that are running
will continue to run for their respective pump delay times,
then turn off.
11. Boiler pump off, system pump continues its delay if
longer.
12. System pump off.
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D D I I S S P P L L A A Y Y
HTR: SH 41% RATE
OUT: 123.0F(129)
HTR: POSTPURGE
OUT: 127.4F(129)
HTR: Standby
OUT: 124.7F(129)
HTR: Standby
OUT: 122.9F(129)
Service Manual