How The Boiler Works; Air Pressure Switch; Boiler Circulator - Weil-McLain GOLD CGs User's Information Manual

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GOLD CGs — User's Information Manual

How the boiler works . . .

Control module
The control module responds to signals from the room thermostat, air pressure switch and
boiler limit circuit to operate the boiler circulator, pilot burner, gas valve and inducer. When
room thermostat calls for heat, the control module starts the system circulator and inducer.
The control module runs the inducer long enough to purge the boiler flue passages, then
opens the pilot valve and activates pilot ignition spark.
The control module allows up to 15 seconds to establish pilot flame. If flame is not sensed
within 15 seconds, the control module will turn off the gas valve, flash the Flame light, and
then enter a 15-second postpurge. The control module will then start a new cycle. This will
continue indefinitely until pilot flame is established or power is interrupted. Once pilot flame
is proven, the control module opens the gas valve to allow main burner flame.
When the room thermostat is satisfied, the control module turns off the gas valve, operates
the inducer for a 15-second postpurge and waits for the next heat call.
The control module indicator lights show normal sequence when the lights are on steady.
When a problem occurs, the control module flashes combinations of lights to indicate the
most likely reason for the problem.
Transformer
The control transformer reduces line voltage to 24 volts for the gas valve and limit circuit.
Inducer
The inducer pulls flue gases through the boiler, causing air to be pulled in through the air
intake opening. The inducer pushes the flue gases through the vent pipe as well.

Air pressure switch

The air pressure switch signals the control module, telling the control module whether air is
moving through the inducer.
Water temperature limit switch
The water temperature limit switch turns off the gas valve if the temperature in the boiler
goes above its setting. (The circulator will continue to run as long as there is a call for heat.)

Boiler circulator

The boiler circulator circulates water through the external (system) piping.
control module provides a pump exercising routine. If the boiler is not operated for 30 days,
the control module will power the circulator for 30 seconds, then off.
Other boiler components:
a supply to system f
b return from system g relief valve (not visible)
c combustion air inlet h air vent connection
d flue outlet i
e gas valve j
pressure/temperature gauge
flame rollout switch
air inlet box
— The
NOTE
k pilot burner and bracket
l stainless steel burners
m cast iron boiler sections
n flue collector
o junction box
Part No. 550-110-261/0999