Scope of Application of the Air Heaters
The Webasto Air Top 3500/5000 air heaters are designed to provide the following features:
- for the heating of driver’s cabs, boats, trucks, small buses, vans and ambulance vehicles
- defrosting the vehicle’s windows.
The heaters operate independently of the vehicle engine and are connected to the fuel tank and the electrical system of the vehicle. They can be used in vehicles with water-cooled or aircooled engines.
Webasto AIRTOP 3500-5000 Mounting the Heater
When mounting the Air Top 3500/5000 heater, the M 6 nuts must be tightened to a torque of 6 Nm +1 Nm. The mounting dimensions as well as the space required for the performance of servicing work are shown in the installation drawing (Fig. 1). The specified horizontal and axial angles of inclination must not be exceeded (Fig. 2).
Webasto AIRTOP 3500-5000 Heating Air 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.
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 heating air intake side which, in conjunction with the heater control element and dependent upon the intake temperature
and position of the setpoint transmitter, operates the heater within the appropriate heat output range. Heat output 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.
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 temperature 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 expected 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.
External Temperature Sensor
The installation of an external temperature sensor is recommended if the heater is installed in an installation housing 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 surfaces 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.
Vehicles with Carburetor Engines
In passenger cars, fuel may only be extracted with the special Webasto fuel pickup (see Fig. 8) and as close to the tank as possible. The connection can be made either in the flow or the return pipe whereby it must be ensured that the return pipe reaches almost to the bottom of the tank. Failing this, the return pipe can be extended. The fuel pickup is to be so mounted that any air or gas bubbles are automatically discharged into the tank (see Fig. 9).
Vehicles with Fuel Injection Engines
When installing the heater in vehicles with petrol injection systems it must be determined whether the fuel pump is mounted inside or outside the tank. Where the fuel pump is located inside the tank, the fuel can only be drawn from the return pipe and only by using the Webasto fuel pickup (see Fig. 8) whereby it must be ensured that the return pipe reaches almost to the bottom of the tank (minimum distance to tank bottom, see Fig. 10). Failing this, the Webasto tank extracting device (see Figs. 9, 10 and 11) can be used. Where the fuel pump is mounted outside the tank, the fuel may only be extracted between the tank and the fuel pump and also only by using the Webasto fuel pickup (see Fig. 8)
Vehicles with Diesel Engines
Fuel must be drawn from the fuel tank or a separate tank (see Figs. 9, 10 and 11). With this method of fuel being supplied from a separate tank, no pressure-related influence is possible.