Theory of Operation
13--Fuel Metering Pump
F--Fuel Supply Line
Once ignition takes place, the flame sensor alerts the
The arctic/cold weather heater is an oil fired heater
control unit, and the control unit shuts off the glow
that pumps coolant from the machine engine, heats it
and returns it to the engine. The heater utilizes
machine 24-volt power and fuel, and operates
When started, the heater runs in the full heat mode
independently of the machine engine. A temperature
and the temperature is monitored at the heat
regulating switch in the unit regulates the coolant
temperature between a low of 53C (127F) and a high
exchanger. When the coolant temperature reaches
72C (162F) the heater starts cycling up and down
of 85C (185F)
between levels (high, medium, low). If the coolant
temperature continues to rise, the heater will
When the heater switch is turned ON, the following
automatically shut off. This occurs when the
temperature reaches 85C (185F).
NOTE: If the heater fails to start the first time, it will
automatically attempt a second start. If the
The water pump continues to circulate coolant after
second attempt fails, the heater will shut off
heater shutdown, to allow the heater to monitor coolant
completely. On the initial start up, the heater
temperature. The heater will automatically restart when
the coolant temperature drops below 68C (154F).
may require several start attempts to
self-prime the fuel system.
The heater continues to run as described above, until
The control unit does a system check (flame sensor,
the heater switch is turned OFF.
temperature, safety thermal cut-out fuse and various
When the heater switch is turned OFF, the fuel
other control unit checks).
The water pump starts circulating the coolant.
metering pump stops delivering fuel and the flame is
The glow plug begins to preheat for 20 - 50
pump continue to run for 130 seconds to cool down.
After 20 - 50 seconds the fuel metering pump starts
delivering fuel and the combustion air blower ramps