User Guide
32
110118-01 12/19
CG-F
Installation, Operating & Service Manual
13 How It Works
1 Control
CG-F boilers are equipped with an Intelligent Hydronic Control. This control combines
features such as ignition control, high limit switch, and circulator relays. Energy is
saved by using a thermal purge feature that starts the circulator and delays burner
start when residual heat is available in boiler.
When thermostat calls for heat, control module starts system circulator, checks safety
limits, and activates vent damper.
Control has 2 demand inputs and 2 circulator output connections. These can be
configured for single zone & indirect water heater or 2 zone system.
When vent damper is opened completely, control module opens pilot valve and
activates ignition spark.
Control module will sense pilot flame. Once pilot flame is established, control module
opens gas valve and main burners will ignite.
When thermostat is satisfied, control module turns off gas valve, deactivates damper,
and deactivates circulator.
Control module indicates boiler status and returns error codes if applicable. See
“Troubleshooting” for guidance with error codes.
2 Transformer
Control transformer reduces line voltage to 24 volts for gas valve and safety limit
circuit.
3
Draft Hood Provides adequate dilution air and ensures proper draft for boiler operation.
Blocked Vent Switch
If vent becomes blocked, switch will open (requiring manual reset) and cause burners
to shut down.
4 Flame Roll-Out Switch
If flames roll out of burner tubes, switch will open (requiring replacement) and cause
burners to shut down. If switch trips, determine cause of flame roll-out.
5 Gas Valve Regulates gas flow to boiler.
6 Pilot Provides ignition source for burner lighting.
7 Vent Damper Closes during off cycles to reduce heat loss from house to vent.
8
IDL 1200
Temperature Sensor/
Low Water Cut Off
(LWCO)
Dual sensor for boiler temperature control and protection against potentially
damaging low water conditions in boiler. In event of low water condition, “LOW
WATER” LED will turn on and control will shutdown burner. Auto reset function allows
boiler to fire when water level is returned to normal.