2 General description
Thermo Pro 90
202
2.1
Combustion air fan
The combustion air fan supplies the air necessary for the com-
bustion process to the burner unit.
2.2
Overheating protection, coolant
temperature sensor and heat
exchanger
The coolant temperature sensor registers the coolant temper-
ature at the coolant outlet of the heater as an electrical resist-
ance. This signal is sent to the control unit where it is
processed.
The heat exchanger transfers the heat generated in the com-
bustion process to the coolant circuit.
The overheating protection (bimetal strip) protects the heater
from impermissibly high operating temperatures. The over-
heating protection trips at a heat exchanger temperature in
excess of 127 ±7 °C and switches off the heater.
The overheating protection is reset automatically at tempera-
tures below 65 ±5 °C.
2.3
Glow plug and burner unit
The fuel is evaporated and precombusted in the burner unit.
The fuel/air mixture is ignited by the glow plug when the
heater is started. The glow plug is axially arranged in the mid-
dle of the burner unit.
2.4
Combustion chamber
The combustion chamber assists combustion of the fuel/air
mixture thus heating the heat exchanger.
Fig. 202 Combustion air fan
Fig. 203 Heat exchanger
2
1
1
coolant temperature sensor
2
overheating protection
Fig. 204 Burner unit
Fig. 205 Combustion chamber
Combustion chamber
