106636-04 - 8/22
34
X-2
Installation, Operating & Service Manual
14
How It Works
1
Control
X-2 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.
WARNING
• An open blocked vent switch is indicative of a problem with the vent system. If blocked vent switch opens,
the cause of the venting problem must be found and corrected by a qualified installer, service agency, or gas
supplier before the blocked vent switch is reset.
• An open flame rollout switch is usually indicative of a plugged heat exchanger. Cause of the flame rollout
must be found and corrected by a qualified installed, service agency, or gas supplier, and switch replaced
with an identical one, before the boiler is returned to operation.
!
