T
HERMO
90 / 90 S
2GENERAL DESCRIPTION
2-1
2. General Description
The Webasto Thermo 90 and 90 S coolant heater, in
combination with the vehicle’s own heating system, is
used to:
• heat the cab, sleeper or interior areas of vehicles
• defog/defrost windshields
• preheat water cooled engines
The coolant 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 is designed around the Ferro-Tec Technology
evaporator burner system and operates intermittently,
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 a range from 1.8 to 7.6 kW (6,100 to
26,000 Btu/hr) for Diesel operated heaters and within 2.0
to 7.6 kW (6,800 to 26,000 Btu/hr) for gasoline operated
coolant heaters. For an extremely high heating
performance requirement (preheating) the maximum
performance of 9.1 kW (31,000 Btu/hr) is available with
diesel operated coolant heaters for up to 2 hours after
heater actuation.
The Webasto Thermo 90 and 90 S coolant heaters
basically consist of:
• combustion air fan
• heat exchanger
• burner insert with combustion tube
• circulation pump
For control and monitoring, the following are located
inside the heater unit:
• control unit (external)
• flame sensor
• glow pin
• temperature sensor
• temperature limiter
On the Thermo 90 S heater, the control unit is flanged to
the combustion air fan. It is possible to remote mount
the control unit using an optional mounting bracket.
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
NOTE:
One of the newer
models shown.
Older models have
the temperature
sensor cable
located on the side.
Heater Thermo 90
