PREVOST H3-41 Manual page 55

cooled engines. It can be used before startup to
facilitate starting and to provide rapid operation
of the interior heating system. It can also be
used with the engine running to maintain coolant
heat and interior temperature.
The heater operates independently of the
engine. It is connected to the cooling system,
heating circuits, and to the coach fuel and
electrical system.
Warning
: The preheating system uses the
same fuel as the engine. Do not operate in a
closed building or while refueling. Operate only
in a well-ventilated area.
Switching the Heater On
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 begins operating. The fuel
metering pump delivers fuel in precise amounts
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, the
glow plug and ignition coil are switched off.
Hot combustion gases are diverted at the end of
the flame pipe and are then forced through the
indirect heating surfaces of the heat exchanger.
The heat exchanger transfers the heat to the
coolant water passing through the heat
exchanger.
The heater is thermostatically controlled and
operates intermittently (i.e., the switched-on time
of the burner varies depending of the heat
requirement). The water temperature is
controlled by the built-in water thermostat.
The water circulation pump remains in operation
as long as the heater is operating; even during
the regulated intervals and during the delayed
cut-out 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 cut-out period). Ignition
takes place after the delayed cut-out time
expires.
Switching the Heater Off
The fuel supply is interrupted when the heater is
switched off. This causes the flame to go out
and a delayed cut-out of 2.5 minutes begins.
The circulating combustion air flushes the
remaining combustion gases out of the chamber
and cools off the heated parts on the exhaust
side of the heat exchanger. The water
circulation pump continues to transfer the latent
heat present in the heat exchanger, thus
preventing hot spots. Once the delayed cut-out
time expires, both the combustion air blower and
the water circulation pump switch-off
automatically. A cut-out will automatically take
place in case of preheater failure. Refer to
Technical Information chapter for more
information.
Water Heater Timer
Note :
Heater timer control pad may differ from
the one described. Refer to your manufacturer's
instruction booklet for detailed operating
instructions.
To set the clock
If the time display e.g. 18:33 is wrong, or if it
flashes 8:88, hold
(backwards) or
hold the button down, the quicker the display
changes. The last few minutes are set
accurately by quick pushes. Adjust to get exact
time, e.g. 23:59. The display fades after 20
seconds.
Present Time Display
Press 4 at any time. Present time appears on
the screen.
Manual Heating Start-Up
Press 5 to switch the heater on or off
immediately. The green light illuminates when
the heater is on.
4-5
OTHER FEATURES
1 and press either
3 (forwards). The longer you
2