Weil-McLain 550-110-260/02002 manual How it works, ① Control module

GOLD CGs Gas-Fired Water Boiler

How it works . . .

①Control 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 (see page 43).

②

③

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.

④Air pressure switch

The air pressure switch signals the control module, telling the control module whether air is moving through the inducer.

⑤Water 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. The circulator is shipped loose, and can be mounted on either the boiler supply or return piping. The factory- installed circulator wiring harness provides ample length for either location. NOTE — The 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 turn off.

Other boiler components:

a	supply to system	f	pressure/temperature gauge	k	pilot burner and bracket
b	return from system	g	relief valve (not visible)	l	stainless steel burners
c	combustion air inlet	h	air vent connection	m cast iron boiler sections
d	flue outlet	i	flame rollout switch	n	flue collector
e	gas valve	j	air inlet box	o	junction box
2				Part number 550-110-260/0200