8 Servicing work
NGW 300 / LGW 300 / GBW 300
806
8.8 Start-up
After the heater is installed, the coolant circuit must be
carefully bled. When this is being done, the motor vehicle
manufacturer’s instructions must be followed.
It must be ensured that all water cocks are opened.
During the trial run, all coolant and gas connections
should be tested for leaks and to make sure that they are
firmly attached. If the heater breaks down while it is being
operated, then troubleshooting should be performed
(see Section 5).
PLEASE NOTE
When the heater is started for the first time after
installation, it is to be expected that there will be some
problems with the burner or the gas pressure regulator at
the beginning, as the air which is present initially in the
gas line leads to a lean gas-air mixture during the first
seconds of operation.
8.8.1 Bleeding the coolant circuit
Set the vehicle’s own heating equipment to "warm" and fill
up with coolant which must consist of a mixture of water
and at least 20 % (glycol-based) anti-freeze. If pure water
is used, there is no protection against corrosion and,
because of the lower boiling point of the water, this can
lead to a partial loss of coolant, in the event of overheating.
If this happens, the coolant must be replenished.
Additives in the coolant must not have an adverse effect
on metals, plastic, or rubber nor must they lead to the
formation of deposits.
Then, allow the vehicle to run at a higher speed, until the
cooler thermostat opens. Shut down the vehicle’s engine
and examine the state of the coolant. If necessary,
replenish the coolant.
To bleed the heating circuit, either
–
switch on the circulating pump (if there is a separate
switching system) or
–
turn the heater on for a short time (max. 5 seconds)
and operate the circulating pump in the add-run.
PLEASE NOTE
The U 4851 and Aquavent 6000 (U 4852) circulating
pumps have dry run protection.
In the case of the U 4851 circulating pump, when it is in a
dry run, the motor will shut down after approx. 10 seconds
in operating mode or approx. 15 seconds after being
switched on.
In the case of the Aquavent 6000 (U 4852) circulating
pump, the dry run was extended to 5 minutes.
The pump is reactivated by disconnecting it from the
power supply for approx. 2 minutes.
Insufficient coolant must be replenished.
Switch on the heater and the vehicle’s own heating fan, if
the engine is shut down. After a certain cooling period, the
heater must turn itself on automatically and abregeln.
If, after that, it is not switched back on, the temperature
limitr has been activated because the heater had not yet
been perfectly bled.
The heater is now locked.
After the system has cooled down and the heater has
been checked for possible damage, in particular to the
temperature limiter’s wiring and the regulating thermostat,
the temperature limiter button must be reset manually.
The heater lock must be removed in accordance with 3.5.