22
Part Number 550-142-785/0812
GWI
Series 2
Gas-Fired Water Boilers –
Boiler Manual
Follow all procedures given in this manual and
“Operating Instructions” when operating the boiler.
Failure to do so could result in severe personal injury,
death or substantial property damage.
1. See page 26
(or boiler “Operating Instructions” label) for
“Operating Instructions.”
2. Raise room thermostat to call for heat.
a. While attempting to satisfy the heat demand, the control
module monitors the boiler temperature changes via the
temperature sensor and determines whether or not the
available hot water will satisfy the demand, only running
the circulator. If additional heat is needed, the sequence
continues. When DHW (if used) calls for heat, sequence
above is bypassed.
3 Blower and circulator energize. After pressure switch proves
airflow, ignition control starts a 30-second prepurge.
4.
Control module sparks
the pilot and opens pilot valve in main
gas valve.
a.
If pilot
does not
light within 15 seconds, pilot valve is
closed and spark generator is turned off. Control module initi
-
ates a 15-second postpurge, then starts a new cycle.
b.
If pilot
does
light and control module senses flame cur-
rent, spark generator is turned off and main valve opens.
c. Natural Gas -
If pilot does not light within 15 seconds,
pilot valve is closed and spark generator is turned off. Control
module waits 5 minutes, then attempts to ignite pilot again.
This cycle will continue indefinitely if pilot ignition control does
not sense pilot flame.
5. During main burner operation:
a. Ignition control monitors pilot flame. If signal is lost, main
gas valve closes and spark starts. Ignition controls starts
a flame-proving cycle as in step 5, above.
b. If power is interrupted, main and pilot gas valves close.
Ignition control will start again at step 3, left, when power
is restored.
6. When the water temperature limit switch opens, the blower
shuts off, causing the pressure switch to open. The ignition
control then closes the main gas valve. The circulator continues
to run.
7. When the thermostat opens (demand satisfied), the ignition
control closes pilot and main gas valves. Blower and circulator
shut down.
8 Boiler is now in the off (stand-by) cycle.
9. Repeat steps 1 through 7 several times to verify controls are
operating correctly.
10. Return thermostat(s) to normal setting.
11. Set the thermostat heat anticipator as instructed in the wiring
diagram (and on boiler wiring diagram label).
9a Sequence of operation
