Lochinvar Commercial Soiler 400-801 - Manual (Page 65)

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11
Operating information
(continued)
Sequence of operation
OPERATION DISPLAY
1. Upon a call for heat, the gas pressure switch(es) must be closed.
2. Once the gas pressure switch(es) are closed, the control turns
on the appropriate pumps (system and boiler pumps for space
heating, DHW pump for DHW). The fl ow switch and/or LWCO
must close.
3. The control turns on power to the louver relay. The louver
proving switch, air pressure switch, and blocked drain switch
must close.
4. The control starts a 15 second prepurge cycle by initiating the
blower.
5. The control starts a 4 second trial for ignition by fi ring the spark
electrode and opening the gas valve.
6. If fl ame is not detected within 1 second after the sparking ends,
the control will perform a 10 second post-purge, then start
another prepurge cycle and try to light the burner again. On
the 501 and larger models, the control will lock out if this second
attempt also fails. On the 400 model, the control will perform a
total of 4 attempts before locking out.
7. If fl ame is detected, it holds the fi ring rate steady for 5 seconds
to let the fl ame stabilize, then it begins to modulate the fi ring rate
based on a set point or some other command (such as a 0-10V
BMS signal).
Installation & Operation Manual