Functional description
Explanation of the cooling system
The cooling system in internal combustion engines con-
sists of a thermostat, water pump, heat exchanger, radiator
and various hoses. In principle, the structure is similar for
all engines. The thermostat controls the circulation of the
coolant. When the engine is cold, the coolant circulates
via a so-called „small cooling circuit“ (a bypass line). If the
heating control is turned to the „heating/warm“ position,
the coolant circulates through the heating circuit from the
engine to the passenger compartment and the passenger
compartment is heated.
When the engine has reached its operating temperature, the
„large cooling circuit“ is opened by the thermostat and the
flow to the radiator is also released.
Brief explanation of the function of the engine preheater
The engine pre-heater is integrated into the cooling circuit
of the vehicle. It heats the cooling water of the vehicle up to
approx. 50/60/75/90°C (depending on the version).
The built-in pump circulates the cooling water and automati-
cally heats all components so that a temperature of approx.
30-50°C is reached at the cylinder liners in the engine, for
example. This has a positive effect on the start-up process
and reduces cold-start wear as well as petrol/diesel con-
sumption during the warm-up phase.
The preheater does not need a bracket, but is fixed and sup-
ported by the coolant hoses.
- Locate the return hose from the cabin heat exchanger to
the engine. If it is unclear which of the normally two hoses
is the correct one, run the engine a little with the heater off
so that it is hand-warm. Turn off the engine and feel both
hoses. The cold hose is the return hose you are looking for.
Be careful not to injure yourself or come into contact with
hot parts! Use an infrared thermometer (order no.: 306497),
for example.
- Check that the installation is possible and that there is
enough space. The preheater must be mounted as shown
in the picture in this manual (outlet at the top, inlet at the
bottom), so that the outlet is always the uppermost point!
- Make sure that the installation position of the preheater is
below the height of the cooling water expansion tank. The
preheater is not self-priming!
- Drain the coolant into a clean container. It may be sufficient
to drain only enough so that the hose on which the prehea-
ter is to be installed is no longer filled.
If the coolant is not renewed, avoid any kind of contaminati-
on! These can block the pump of the preheater and possibly
destroy the unit. Attention! Depending on which coolant or
which additives are used in the coolant, the manufacturer‘s
disposal instructions must be observed. The coolant must
be disposed properly and must not be allowed to enter the
ground or the normal sewage system. Ask the manufacturer
or a specialist workshop about the proper disposal and
handling of coolant. Coolants contain glycol/ethanediol and
are harmful if swallowed.
Avoid contact with skin and eyes. Keep out of the reach of
children. If swallowed, seek medical advice immediately and
show the container or label.
- After all the previous points have been taken into account,
you can disconnect the selected coolant hose at a suitable
point.
- If there is no non-return valve in the cooling circuit, the pre-
heater can be installed in such a way that either the engine
is preheated first or the interior heat exchanger is preheated
first, depending on your preference (the „warm“ outlet con-
nection is the connection located above in the immediate
vicinity of the power cable connection).
- If a self-regulating valve is installed in your vehicle (usually
with automatic air conditioning), it is necessary to use the
T-piece supplied to create a direct flow between the supply
and return lines and the preheater.
- Route the coolant hoses to the connection pieces of the
pre-heater and secure them with the hose clamps included
in the scope of delivery.
- Lay the electrical connection cable as required, observing
the safety instructions described above.
- It is possible, for example, to lay the connection plug up to
the radiator grille of the vehicle so that the unit can be ope-
rated without first opening the bonnet. In this case, please
cover the connector plug with a plug when the unit is not in
use.
- Another alternative would be to install the unit inside the
vehicle.
Commissioning
The preheater may only be operated from an earthed socket
outlet with an upstream residual current circuit breaker
(30mA). For more information, please contact a qualified
electrician. A residual current circuit breaker is normally
installed in standard house installations. Observe the safety
instructions when handling the coolant. The first two warm-
up cycles after commissioning must be carried out under
supervision. The unit‘s own operating interval must not be
less than approx. 10 min!
The unit must not be operated without water or with frozen
cooling water. Do not operate the engine preheater if there
are persons in the vehicle. Before operating the engine
pre-heater, always make sure that there are no leaks and
that there is no moisture in the electrical connection plug.
Operation must be supervised. If the engine pre-heater re-
mains installed in the vehicle all year round and is not used
in summer, it is necessary to carry out a heating phase three
times a month to prevent deposits in the unit. Do not touch
the unit during operation. Disconnect the mains plug before
working on the unit.
The engine pre-heater may only be operated with the origi-
nal mains cable from the scope of delivery.
