How It Works - Weil-McLain GOLD CGt Manual

GOLD CGt Gas-Fired Water Boiler — Boiler Manual

How it works . . .

①
Control module
The control module responds to signals from the room
thermostat, tankless heater low limit, 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
Transformer
The control transformer reduces line voltage to 24 volts for
the gas valve circuit.
③
Inducer
The inducer pulls flue gases through the boiler, causing air to
be pulled in through the boiler air openings. The inducer
pushes the flue gases through the vent pipe as well. The inducer
is shipped with gasket and 4 nuts inside a carton located inside
the crate. See Figure 36 on page 57 for proper installation of
inducer.
④
Air pressure switch
The air pressure switch signals the control module, telling
the control module whether the inducer is working correctly
or the vent is blocked.
⑤
High limit
The high limit 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.)
Other boiler components:
a supply to system
b return from system
c stainless steel burners
d flue outlet
e gas valve
f pressure/temperature gauge
2
⑦
⑧
⑨
g relief valve
h air vent connection
i flame rollout thermal fuse element (TFE)
j burner holding bracket
k pilot burner and bracket
l gas manifold
Boiler circulator
The boiler circulator circulates water through the
external (system) piping. The circulator is shipped
loose, and must be mounted on the boiler return
piping as shown. 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.
Tankless heater low limit control
This control provides domestic priority by diverting
all available heat to domestic water heating whenever
it senses water temperature below its setting.
3-Way valve
If the tankless heater low limit control senses boiler
water is too cool to provide domestic water from the
coil, the 3-way valve diverts all of the hot water flow
from the boiler back to the return, dedicating all
available heat for domestic water. The 3-way valve is
shipped inside the inducer carton.
this valve and fittings as shown. See pages 21 and
60 for details
Make sure the valve body is in the correct position as
shown on page 3 and Figure 39, page 60. Valve port
"A" must connect to boiler supply piping. Valve port
"AB" must connect to boiler return piping. Valve port
"B" must be used for the system return connection.
This allows water to flow normally from port "B" to
port "AB" during a space heating cycle. The valve stops
space heating circuit flow and switches to full
recirculation (flow from port "A" to port "AB") when
the tankless heat low limit control closes.
Tankless heater
The tankless heater uses hot boiler water to heat
domestic water.
Wires to ambient temperature
switch
Install the switch and bracket supplied with the boiler
on the wall closest to the boiler, within 5 inches of the
enclosure ceiling. This switch senses the ambient
temperature in the boiler space. Should boiler room
temperature rise too high due to insufficient
ventilation air, the switch will cycle the boiler off when
the temperature at the switch reaches 135°F.
m cast iron boiler sections
n flue collector
o junction box
p drain valve
q burner shield
Part Number 550-110-290/0501
You must install