Heater Sequence Of Operation - Raypak X-THERM 1005–2005 Installation & Operating Instructions Manual

Heater Sequence of Operation

If all limits are satisfied and there is a call for heat:
1. The internal heater primary pump will start and
begin circulating water in the heater's primary heat
exchanger and the injector pump(s) will be pow-
ered and enabled.
2. The blower is powered and goes through a 15 sec-
ond prepurge from when air flow is proven by
closure of the blower suction air pressure switch.
3. The igniter will be powered and once proven will
heat up for 20 seconds.
4. The gas valve is then energized for a 4 second
trial for ignition period. Trial for ignition is fixed at
50% input. The heater is allowed to modulate
once flame is proven and the firing rate will adjust
to match the load based on the configuration and
settings of the temperature control or external
input.
5. As the water approaches 120°F entering the pri-
mary heat exchanger the injector pumps will begin
feeding water from the system into the heater,
operating to maintain 120°F minimum into the pri-
mary heat exchanger.
6. Once the heat demand is satisfied the gas valve
will close and the blower will run a 30 second post
purge. The heater pump will continue to circulate
water for 0 to 10 minutes depending on the pump
delay setting on the Raypak modulating tempera-
ture control.
California Hot Water Supply, Inc.
Ignition Module
When additional heat is needed, the combustion air
blower starts to purge air from the combustion cham-
ber for 15 seconds. On proof-of-air flow, the
air-proving switch closes and the igniter is energized.
To ensure safe operation, the gas valve cannot open
until the igniter is verified. The main burner is automat-
ically lit when the device is powered and pre-purged.
The heater performs its own safety check and opens
the main valve only after the igniter is proven to be
capable of ignition. The standard ignition module will
attempt to light three times before locking out. To reset
it, turn off power to the heater, wait 30 seconds and re-
apply power.
Fig. 36: Ignition Module
The optional single-try ignition module will lock out
after failing to light one time. To reset it, press and
release the small, recessed black push button located
inside of the cut-out on the lower right-hand corner of
the ignition module case. Turning off the power to
the heater WILL NOT reset the single-try ignition
module.
36
(800) 249-7244 36