TM 9-2540-207-14&P
HEAT EXCHANGER
The Heat Exchanger transfers the heat from the combustion gases to the ventilation air stream. Hot combustion gases
from the Burner enter the Heat Exchanger, circulate through a number of passage ways and exit through the Exhaust
Port. Ventilation air is passed from the Ventilation Air Inlet end of the Heater, blown through the Heat Exchanger (where it
exchanges heat from the walls of the flame tube), and then exits at the Ventilation Air Outlet end.
!Warning!
Nothing should be welded, screwed or otherwise attached to the Heat Exchanger
because this may cause the Heat Exchanger to leak and introduce toxic fumes into
the ventilation air stream.
COMBUSTION AIR SYSTEM
Combustion air is drawn either from inside the vehicle (single air mode), or from outside the vehicle (dual air mode), using
a fan and motor completely separate from the ventilation air system. (The combustion fan and motor are located in the
Top Housing). The combustion air is then blown into the Burner in two locations, through primary, and secondary air
ducts.
If combustion air is coming from outside the vehicle, then the Combustion Air Inlet must be connected to a duct, and in
turn to the outside of the vehicle. The Combustion Air inlet connects to a 1.5" inside diameter duct that must be suitable
to withstand ambient temperature and humidity conditions and an internal negative pressure of 10 inches water column.
The Combustion Air Duct must be securely clamped at the Dual Air Adapter Assembly.
Note: The nozzle of the Dual Air Adapter can swivel 360° to align with the vehicle's
combustion air inlet ducting.
Note: The Heater does not require a combustion air filter.
FUEL DELIVERY
Fuel is delivered by a Fuel Pump and a Fuel Injector located in the Top Housing. The Fuel Pump is used to boost the fuel
pressure during extremely cold weather and low fuel pressure conditions so that sufficient fuel is delivered for heating.
Note: The Heater can be operated without the Fuel Pump functioning as long as
the fuel supply remains at reasonable temperatures and pressures.
The Fuel Injector is used to regulate fuel flow with a high degree of resolution (from 0% to 100% flow). Since the Injector
is normally closed, it must receive signals from the Programmed Controller to deliver fuel. As an additional safety feature,
a Thermal Fuse is placed in line with the injector control signal so that if a serious over temperature condition should
happen, the injector control signal is interrupted, and the normally closed Injector will stop fuel flow.
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