Webasto Air Top 3500 ST Installation Instructions Manual - page 8
Heating Air System
NOTE:
It is not permissible to integrate the heater into the vehi-
cle’s air ducting system.
Both recirculated-air and fresh-air operation is permissible.
In the case of fresh-air operation, care must be taken that
the heating air is extracted from an area that is protected
against splashwater and spray.
NOTE:
In the case of fresh-air operation, an external temperature
sensor must be mounted within the space to be heated.
A temperature sensor is installed in the heater on the heat-
ing air intake side which, in conjunction with the heater con-
trol element and dependent upon the intake temperature
and position of the setpoint transmitter, operates the
heater within the appropriate heat output range. Heat out-
put is so adjusted that after a quick reaching of the preset
interior temperature the same will be maintained at the
preset value.
Minimum inside diameter of heating air pipe is
90 mm at Air Top 5000
80 mm at Air Top 3500
may be decreased to 75mm subject to prior approval by
the manufacturer.
NOTE:
For heating air ducts only materials capable of withstand-
ing a temperature of at least 150° may be used.
The hot air discharge opening is to be located so that the
hot air is not directed onto parts that are not resistant to
heat.
CAUTION:
In vehicles designed for the transportation of passengers,
the air outlet openings must be arranged in such a way
that they cannot be obstructed by passengers.
Maximum air pressure drop between intake and delivery
side of the heating air line:
Air Top 3500 2,0 mbar (20 mm WH)
Air Top 3500 Volume Plus 3,0 mbar (30 mm WH)
Air Top 5000 3,0 mbar (30 mm WH)
The test can also be performed by measuring the tempera-
ture directly at the heater:
temperature difference between heating air inlet and hot
air outlet max. 130 K.
If this value is exceeded, the temperature limiter is ex-
pected to trip. The heating air hose is to be secured at the
joints.
The hot air stream must be prevented from re-entering the
heater, if the heater is operated in the recirculating mode
without any hot air ducting
CAUTION:
If the heater is operated without heating air intake hose, it
is imperative that the air intake grille supplied with the
heater be mounted!
NOTE:
The installation must be checked for the following:
- “closed circuit” of air between the vehicle heater and the
heater
air
inlet
- “closed circuit” of air between heater air inlet and heater
air outlet (fig. 7)
- adequate space for taking in heating air (heating air to be
extracted from the cool space of the cabin, e.g. in the
case of installation underneath a bunk)
If an installation housing is used, the area around the air
discharge nozzle must be tightly sealed so that no hot air
can enter the installation box.
External Temperature Sensor
The installation of an external temperature sensor is rec-
ommended if the heater is installed in an installation hous-
ing or in location with poor ventilation (e.g. under-neath
bunks). Extremely short cycle times of the heater can thus
be avoided.
Mounting of External Temperature Sensor
The external temperature sensor must be mounted on sur-
faces as vertical as possible, at mid-height in the vehicle
cab in the area to be heated.
The temperature sensor must
not
- be located directly in the hot air stream (vehicle’s or
heater’s heating air).
- be mounted in the vicinity of heat sources
(e.g. vehicle’s heating system).
- be exposed to direct sun radiation (e.g. on the
dashboard).
- be mounted behind curtains or the like.
Fig. 7:
Heating air inlet and heating air outlet
Fig. 7a:
Heating air inlet with intake grille
Air Top 3500/5000
6
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