Heating circuit function

S83.20-2504-11

Heating circuit, manual heating

1 Engine radiator

2 Engine

3 Coolant pump

4 Heat exchanger, heater

5 Heater valve

S83.20-2505-11

Heating circuit with Code H17 and/or Code H06

1 Engine radiator

2 Engine

3 Coolant pump

4 Heat exchanger, heater

M10 Auxiliary pump, heated water (engines 111 and 611)

M45 Auxiliary pump, heated water (engine104.900)

Y37 Cycle valve

S83.20-2506-11

Heating circuit with water, auxiliary heating and/or auxiliary heater

1 Engine radiator

2 Engine

3 Coolant pump

4 Heat exchanger, heater

A34 Water, auxiliary heating

A87 Water, auxiliary heating with auxiliary heater function

A90 Heater booster

A34+

A90 Tandem version (Water, auxiliary heating and auxiliary heater built in series)

M10 Auxiliary pump, heated water (engines 111 and 611)

M45 Auxiliary pump, heated water (engine104.900)

Y37 Cycle valve

The refrigerant pump (3) pumps cold cooling water through the engine (2), where the refrigerant soaks up the engine heat and so heats the water. The heated refrigerant is then fed through the heat exchanger (4), where the heat is transferred to the inner space.

With manual heating the quantity of refrigerant directed to the heat exchanger (4) is controlled by the water valve (5) and, in the case of automatic heating/Tempmatic, by the cycle valve (Y37). The coolant is returned to the coolant pump via the coolant return.

Most of the refrigerant does not flow through the heater, but to the refrigerant thermostat. Depending on

the coolant temperature, the thermostat directs the water through the radiator (1) or direct to the coolant pump (3).

In the heating system, the auxiliary water pump (M10/M45) is installed before the cycle valve (Y37). Same positioning, with or without auxiliary heater/stationary heater.

Three basic versions differentiate the heating circuit:

 Manual heating

 Heater regulation (automatic heater/Tempmatic)

 Heating circuit with auxiliary heating (AHE) and/or heater booster (ZUH)