Preheating Systems - PREVOST Motorcoach XL Series Operator's Manual

knob clockwise to
counterclockwise to decrease.
9. "A/C auxiliary" switch
Push down rocker switch to actuate the optional
auxiliary A/C system located at rear of coach to
supplement the central A/C system.
How to use the controls
• To ventilate without heat or air conditioning
Turn the "temperature" control knob to the
maximum counterclockwise position (cool), turn
the "recirc.-fresh air" control knob to the maximum
clockwise position (fresh air), then set the "A/C-
heat" switch to the "heat" position and turn the fan
speed control knob to the desired position.
• To defrost
To obtain the maximum defrosting efficiency,
switch the "fan" speed control to the highest
position, turn the "recirc.-fresh air" control knob to
the maximum clockwise position (fresh air), turn
the "feet air outlet" control knob to the maximum
counterclockwise position (defrost position), then
turn the "temperature" control to the maximum
clockwise position (warm).
• To dehumidify
Because an air conditioner dehumidifies as it
cools, you can use it in cool weather to help defog
the windows. Set the "A/C-heat" switch to the
"A/C" position, turn the "feet air outlet" control knob
to the maximum counterclockwise position (defrost
position) then adjust the "temperature" control to a
comfortable setting. With this set-up, the A\C and
heating will run simultaneously, thus drying air as it
flows through the evaporator and then heating it as
it flows through the heater radiator.
CAUTION:
The air conditioning system should
not be used when outside temperature is below
° °
40 F (5 C).
• To turn everything OFF
Set the "A/C-heat" switch and "fan speed" control
knob to the "OFF" position and turn the
"temperature" control knobs to the maximum
counterclockwise position (cool).

PREHEATING SYSTEMS

increase air flow
STARTING AND STOPPING PROCEDURES
(Optional)
and
ESPAR (EBERSPÄCHER)
Description of operations
This Auxiliary Preheating System is used for
preheating and retaining the heat of water-cooled
engines. It can be used before starting the engine
to ease its starting and to provide immediate inside
heat upon operation of the heating system. It can
also be used with engine running to maintain
coolant heat and maintain the set temperature
inside vehicle.
The heater operates independently of the vehicle
engine. It is connected to the cooling and heating
circuits, the fuel system and the electrical system
of the vehicle.
The pilot lamp turns on when the heater is
switched on. Combustion air flows in to flush out
the combustion chamber, and the water circulation
pump is put into operation.
pump conveys fuel in precise doses to the
combustion chamber, where fuel and combustion
air form a combustible mixture which is ignited by
the glow plug.
Once the flame sensor has signaled to the control
unit that combustion has taken place correctly, the
glow-spark plug and ignition coil are switched off.
The hot combustion gases are diverted at the end
of the flame pipe, then pass through the indirect
heating surfaces of the heat exchanger and
transmit their heat to the water passing through the
heat exchanger.
The heat is thermostatically controlled, and
operates intermittently, i.e. the switched-on times
of the burner vary depending on the heat
requirement. The water temperature depends on
the setting of the built-in water thermostat.
The water circulation pump remains in operation
as long as the heater is operating - even in the
regulation intervals and during the delayed cutout
of the switched-off heater. The pump can also be
operated independently of the heater by means of
an appropriate circuit. The heater can be switched
on at any time, i.e. during the delayed cutout
period too. Ignition takes place once this delay
time is over.
When the heater is switched off, the fuel supply is
interrupted. The flame goes out, and at the same
time a delayed cutout of some 2.5 minutes begins.
The combustion air still flowing flushes the
remaining combustion gases out of the chamber
4 - 13
:
The fuel metering