Lochinvar 400 - 801 service manual From previous page Sequence of Operation

Service Manual

1Service

Table 1-1(continued from previous page) Sequence of Operation

		OPERATION						DISPLAY
8. If the space heating call for heat is active, and the tank
thermostat or sensor starts a DHW call for heat, the boiler will
switch to the DHW mode. If programmed for normal DHW
operation (not as a zone), the DHW pump will turn on first, then
the	boiler	pump	will	turn	off 2	seconds later.
This will divert the boiler’s outlet water from the heating system
and	send	it	to	the	tank	coil	instead.
The control will then modulate to maintain the outlet
temperature to the DHW boiler set point.
9. If the boiler is not part of a Cascade, and both the space heating
and DHW calls for heat remain active long enough, the boiler will
switch back and forth between the two heating 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 continue to run during a 10 second
postpurge.
11. Any pumps that are running will continue to run for their
respective pump delay times before turning off, unless
programmed		to		remain	on	continuously.
A 60 second anti-cycle period will start, which will delay any
new call for heat until it times out.
12. In Standby, ready to start a new cycle.

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