Webasto Thermo 90, Workshop Manual

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Thermo 90 2 General Description
201
2 General Description
The water heater Webasto Thermo 90 and Thermo 90 S
in combination with the vehicle's own heating system is
used to:
– heat the cabin
– defrost the windshields
– preheat water-cooled engines.
The water heater operates independent from the vehicle
engine and is connected to the cooling system, the fuel
system, and the electrical system of the vehicle.
The heater, designed to the evaporator principle,
operates intermittently and is controlled by the
temperature sensor.
Dependent on the deviation of the current coolant
temperature from the rated value of the temperature
sensor, combustion performance is continuously
controlled within the range from 1.8 to 7.6 kW for Diesel
operated heaters and within 2.0 to 7.6 kW for fuel
operated water heaters. For an extremely high heating
performance requirement (preheating) the maximum
performance of 9.1 kW is available in case of Diesel
operated water heaters for up to 2 hours after equipment
activation.
The water heater Thermo 90 and Thermo 90 S basically
consists of:
– combustion air fan
– heat exchange
– burner insert with combustion tube
– circulation pump
For control and monitoring a
– control unit (external)
– flame sensor
– glow plug
– temperature sensor
– temperature limiter
are located inside the unit.
On the Thermo 90 S heater the control unit may also be
flanged to the combustion air fan.
Fuel supply is provided externally by a fuel dosing pump.
Heater Thermo 90
Thermo 90
1 Combustion Air Fan
2 Fuel Connection
3 Temperature Sensor
4 Temperature Limiter
5 Heat Exchanger
6 Inlet, Coolant
7 Circulation Pump
8 Outlet, Coolant
9 Outlet, Exhaust
10 Inlet, Combustion Air
1
2
3
4
5
6
7
8
9
10
NOTE
One of the newer models shown. Older
models have the cable of the temperature
sensor located on the side.