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ULTRAFORCE COMMERCIAL GAS WATER HEATER
SUF 120 thru 400 SERVICE HANDBOOK
State Water Heaters – Technical Training Department 21 Ashland City, Tennessee © 2009
Servicing should only be performed by a Qualified Service Agent 198152-002
CONTROL SEQUENCE FLOW CHART
Power on
Control displays
model,
temperature
setting and
status
The control
performs internal
system checks
and determines
tank temperature
is below set point
If checks are not
passed the
control will
display an error
or warning.
If all checks are
passed and there is
a call for heat the
blower is energized
for a pre purge
cycle
The control will
store an error
history to show
what fault occurred
and the time
elapsed since the
fault.
When the pre
purge is complete
power is applied to
the igniter for
Warm-up.
At the conclusion
of the igniter
warm up the gas
valve will open for
4 seconds.
If the control
senses flame the
water heater will
fire until the set
point is reached.
If the control fails
to see flame the
blower will continue to
run for a 30 second
Inter purge. There will
be 3 trials for ignition
before a fault is
declared.
At the conclusion
of the inter purge
the igniter will
warm and the gas
valve will open.
At the conclusion
of the heating
cycle the blower
will enter a post
purge cycle and
the control will
enter an idle state.