Weil-McLain 550-110-260/0508 Boiler User Manual


 
Part number 550-110-260/0508
2
GOLD CGs Gas-Fired Water Boiler — Boiler Manual
How it 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 fl ue passages, then opens
the pilot valve and activates pilot ignition spark.
The control module allows up to 15 seconds to establish pilot fl ame. If fl ame is not sensed
within 15 seconds, the control module will turn off the gas valve, fl ash the Flame light, and
then enter a 15-second postpurge. The control module will then start a new cycle. This will
continue indefi nitely until pilot fl ame is established or power is interrupted. Once pilot fl ame
is proven, the control module opens the gas valve to allow main burner fl ame.
When the room thermostat is satisfi ed, 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 fl ashes combinations of lights to indicate the most likely
reason for the problem (see page 45).
Transformer
The control transformer reduces line voltage to 24 volts for the gas valve and limit circuit.
Inducer
The inducer pulls fl ue gases through the boiler, causing air to be pulled in through the air intake
opening. The inducer pushes the fl ue 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. 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.
a supply to system
b return from system
c combustion air inlet
d ue outlet
e gas valve
f pressure/temperature gauge
g relief valve (not visible)
h air vent connection
i ame rollout switch
j air inlet box
k pilot burner and bracket
l stainless steel burners
m cast iron boiler sections
n ue collector
o junction box
Other boiler components: