Truma Combi D 6 AU, Operating Instructions Manual

6

Drain valve

The drain valve automatically equalises the pressure in the 

event of overpressure in the system. When this occurs, the 

water is drained to the outside in intermittent bursts via a 

drainage socket.

This drain valve does not protect the water  container 

from 

frost damage.

c

b

a

d

Fig. 4

a  = Lever in position “Operational – closed”

b = Lever in position “Operational – closed”

c  = Lever in position “Drain”

d = Drainage socket (led outside through floor of vehicle)

Opening the drain valve

– Move lever to position (c) – vertical. The water from the hot 

water system drains through the drainage socket (d).

The drainage socket (d) of the drain valve must be free of 

blockages (slush, ice, leaves, etc.) at all times so the water 

can drain easily! 

No warranty claims for frost damage 

will be accepted.

Closing the drain valve

– Move lever to position (a) or (b) – horizontal.

Filling the hot water system

Check whether the drain valve is closed (see “Closing the 

drain valve”).

– Switch on the power for the water pump (main switch or 

pump switch).

– Open hot water taps in kitchen and bathroom, (set prese-

lecting mixing taps or single-lever fittings to “hot”). Leave 

the fittings open for as long as it takes for the hot water 

system to displace the air and fill up and the water to flow 

without interruption.

If only the cold water system is being operated without 

the hot water system, the hot water system also fills up 

with water. To avoid frost damage, the hot water system 

must be drained via the drain valve, even if it was not 

operated. 

In the event of frost, filling may be prevented by residual wa-

ter that has frozen. The hot water system can be thawed out 

again by briefly starting it up (max. 2 minutes). Frozen lines 

can be thawed out by heating up the interior.

If connected to a central water supply (rural or urban 

connection), a pressure reducer must be used, which 

will prevent pressures of greater than 280 kPa from occurring 

in the hot water system.

Draining the hot water system

– Switch off the power for the water pump (either by the main 

switch or the pump switch).

– Open hot water taps in kitchen and bathroom.

– Open drain valve:  

Lever in vertical position, position (m).

The hot water system is now drained directly to the outside 

via the drain valve. Place a bucket beneath the outlet to check 

whether the water has completely drained away (10 litres). 

There shall be no claims under guarantee for damage 

caused by frost!

Initial start-up

(or when the fuel tank has run empty)

Filling the fuel lines

The heater normally has to be started up several times to fill 

the fuel lines.

Connect unit to control panel to do this. The unit automati-

cally performs 2 start attempts (initial start and repeat) per 

switch-on procedure with a run time of 2 minutes in each 

case. If no flame is detected after the repeat start, the unit 

switches to fault and has to be switched off and on again at 

the control panel. 

After a total of 15 unsuccessful starting attempts (initial 

and repeat start) without forming a flame, the equipment 

is blocked. To remove the block, please contact the Dometic 

Service Centre (see www.truma.com).

Check fuel lines and connections for leaks after filling the fuel 

lines. 

Start-up

The interior can be heated with or without water, depending 

on the setting. 

– Check to make sure the cowl is unobstructed. Remove any 

covers that may be present.

– Fill the hot water system with water if necessary (see “Fill-

ing the hot water system”).

– Switch on the unit on the control panel.

Switching off

– Switch the heater off on the control panel. 

– The switch-off procedure may be delayed by several min-

utes because of internal heater operations.

Always drain water if there is a risk of frost!