17
Part Number 550-110-732/0703
GWS
Gas-Fired Water Boilers –
Boiler Manual
9
Sequence of operation
Figure 12
GWS control module sequence of operation (based on indicator light status)
Follow all procedures given in this manual and
“Operating Instructions”, Section 10, page 19 and on
the inside of the boiler jacket panel, when operating
the boiler. Failure to do so could result in severe
personal injury, death or substantial property damage.
1. Raise room thermostat to call for heat.
2. Inducer and circulator energize. After pressure switch proves
proper airflow, control module initiates 10-second prepurge.
3. 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 initiates a 15-
second postpurge, then starts a new cycle.
b.
If pilot does light and control module senses flame current,
spark generator is turned off and main valve opens.
4. During main burner operation:
a.
Control module monitors pilot flame current. If signal is lost,
main valve closes, spark generator activates and sequence
returns to step 4.
b.
If power is interrupted, control system shuts off pilot and main
gas valves and restarts at step 1 when power is restored.
5. In the event the limit control shuts down the boiler — The
control module closes the gas valve, but keeps the inducer
operating for 15-second postpurge.
— The circulator continues to operate.
6. Lower room thermostat setting to stop call for heat. Thermostat
is satisfied — Pilot and main gas valves are closed — Inducer
operates for 15-second postpurge — Circulator is shut off.
7. Boiler is now in the off cycle.
8. Repeat steps 1 through 6 several times to verify operation.
9. Return the thermostat to normal setting.
10. Set thermostat heat anticipator setting per wiring diagram,
page 18.
