HDT Camfire CV125CG, Operation Manual

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10
B. Principle of Operation
Fuel System
An air pump on one end of the motor shaft forces the air through the nozzle. The moving air lifts fuel from the tank
by a siphon action and carries it into the combustion chamber in a fine spray.
Air System
The air system is divided into two parts, both of which are supplied with air from a fan which is attached to the
other end of the motor.
Part of the air from the fan enters the combustion chamber where it mixes with the atomized fuel to become a
combustible mixture, and also mixes with the burning gases to complete the process of combustion.
The exhaust gases from the combustion chamber circulate within the inner surfaces of the heat exchanger. They
are then ducted out of the heater through the stack adapter on its’ top and out of the heater space through a flue
pipe.
The rest of the air from the fan passes over and around the combustion chamber and through the heat exchanger
where it is heated and emerges from the front of the heater as a powerful stream of heated fresh air, without being
mixed with the products of combustion.
Ignition System
The ignition system consists of a transformer and spark plug. The transformer increases the input voltage to a
very high potential which causes an arc to be drawn between the electrodes of the spark plug. The arc is used to
ignite the fuel and air mixture within the combustion chamber.
Control System
The safety control circuit consists of a duct over heat switch, a light sensitive photocell, and a safety control. The
safety control will trip if the heater fails to ignite or the flame goes out, thereby causing the heater to shut down.
The photocell is used to sense the presence of light due to the flame inside the combustion chamber. It varies its’
electrical resistance in relation to light rays. When under the influence of light, the cell has very low resistance. The
resistance is high when little or no light strikes the light sensitive surface. The flame sensor’s function is to control
the safety control.
A ”duct over-heat” switch is located at the outlet end of the heater. This switch will shut down the heater if the duct
temperature exceeds approximately 275 deg. F.
A thermostat accessory, Part No. CAH-134, may be incorporated into the electrical circuit of the heater. The
thermostat can be set to any desired temperature between 35 deg. F and 95 deg. F. When the temperature of the
surrounding air reaches the pre-set temperature, the thermostat contacts open and cause the heater to shut down.
When the air cools, the thermostat contacts close and the heater recycles.