Thermo 90 S / Thermo 90 ST 2 General description
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2 General description
Thermo 90 S and Thermo 90 ST water heaters operate in
conjunction with the vehicle’s own heating system and
serve
– to heat the cab,
– to defrost the vehicle windows and
– to preheat water-cooled engines.
The water heater operates independently of the engine
and is connected to the cooling system, the fuel system
and the electrical system of the vehicle.
The concept of the heater is based on the evaporator
principle. It is controlled by the temperature sensor and
operates intermittently.
Depending on the deviation between the current coolant
temperature and the nominal value measured at the
temperature sensor, the burner power is regulated
between the limits of 1.8 to 7.6 kW in diesel heaters and
1.8 to 7.6 kW in petrol heaters. When the heating
requirement is particularly high (preheating), diesel
heaters provide a maximum power of 9.1 kW for up to
2 hours after the heater is switched on.
The Thermo 90 S and Thermo 90 ST heater is principally
composed of
– the combustion air fan
– the heat exchanger
– the burner insert with combustion pipe
– the circulating pump
To control and monitor it, the heater has
– a control unit (external)
– a flame monitor
– a glow plug
– a temperature sensor
– a temperature limiter
inside it.
In the case of the Thermo 90 S heater, the control unit can
also be flange-mounted on the combustion air fan.
The Thermo 90 ST heater is delivered with the control unit
already flange-mounted on the combustion air fan.
Thermo 90 S heater
Thermo 90 S
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2
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4
5
6
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1 Combustion air fan
2 Fuel connection
3 Temperature sensor
4 Temperature limiter
5 Heat exchanger
6 Inlet, coolant
7 Circulating pump
8 Outlet, coolant
9 Outlet, exhaust gas
10 Inlet, combustion air
11 Control unit (can also be
arranged externally in the
vehicle)
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