# Trumatic C3402/6002 hot water light - when does it come on ?



## AndrewBingham (Jun 14, 2008)

Hi

My Hymer B544 has a Trumatic C3402 (I think - might be C6002) heating/hot water system.

It seems to be working fine - except sometimes there is not a lot of hot water, and sometimes there is. I can tell this by the length of the shower I can take in the morning before the water stars to run cooler.

The amber light which Truma states is "Water heater heating-up phase" rarely goes on. After a longish shower I would have thought this light should go on during a longish shower as , presumably, cold water enters the system and needs heating up. Or does it not work that way?

thanks

Andrew


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## Boff (May 10, 2005)

Hi Andrew,

as long as the Trumatic C heater is switched to "Summer" mode (hot water only, no heating), the yellow light indicates that the gas burner is running to heat up water. In "Winter" mode (hot water and heating) the light simply indicates that the water temperatur has fallen below the threshold value. If room heating is already operating, then the system will simply wait until the excess heat from room heating has warmed up the water sufficiently. Or, if that is not enough, will continue to run the burner (like in summer mode) after the room heating cycle has ended.

But take a look at the water temperature setting! And keep in mind that the boiler contains just 12 litres of water. If water temperature is set to 40 degrees, then this is barely enough for a longish shower. With 60 degrees you have to add more cold water, so 12 litres are more than enough. 

Of course it could also be that the temperature sensor is not properly working.

Best Regards,
Gerhard


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## Rapide561 (Oct 1, 2005)

*Heating*

Hi

I had the C6002 EH in the previous van and left the heat selector on 1800 watt electric at all times, and the water heat setting to 60 degrees. The orange light came on now and again to keep the water hot.

It did exactly the same in the winter mode - ie providing heating for the van and hot water.

I am now using one of the new Combi 6 E and it is the same.

I agree with Boff about running the water at 60 degrees though.

Russell


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## AndrewBingham (Jun 14, 2008)

*Seems like magic*

Thanks for all the advice.

Odd thing is I (almost) never have seen the yellow light on or hear the boiler running. Admittedly I am out most of the day but even so after washing up etc in the evening and shower in the morning I would expect the light to come on (?)

The light "works" because when I switched to 60 after a period on 40 the yellow light came on for about 30-40 minutes.

There has always been HOT water though - even tho I have not seen the yellow light on. Sometimes it is Hotter than at other times.

I am beginnign to suspect a fault thermostat somwhere.... or else it is magic


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## Boff (May 10, 2005)

Hi Andrew,

the Trumatic C boilers are rather well-insulated. So if the boiler is fully heated up and no hot water is used, it can easily last several hours without re-heating. And if room-heating is switched on then even longer, because every room-heating cycle also heats up the water a bit.

However, if you observe large temperature _variations_ that cannot be explained by the hot water supply simply being used up, then indeed most probably the thermostat is faulty. Then you should visit a Truma service centre.

Best Regards,
Gerhard


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## AndrewBingham (Jun 14, 2008)

*Possible Explanation*

FWIW in case it helps someone else here are some facts that might explain this problem

1 I fill my water tank using a hose

2 I recently added a hozelock spray attachment to the hose

3 I have filled the tank 3 times using this attachment on the hose which when fully open gives less water per minute at a higher pressure

4 When I got home today no water came out of the taps

5 I checked inside the water tank and a hose from the pump to a connector had come off at one end

6 I re-attached the hose and - after a bit of air gurgled out of the taps - hot and cold water now runs fine.

7 After this the hot water light came on.

8 I think the water running pressure is higher than before.

SO POSSIBLY
a) The higher pressure filling of the tank caused the pump hose to gradually slip off.

b) This reduced the water intake to the boiler enough that it (for some internal safety reason) did not add enough water to the boiler after water was used for it to heat the water continuously.

or c) This added enough air to the system to cause the boiler not to heat the water.

b) and c) might be intermittent

I thought the water pressure was sometimes lower than usual but was not sure.

Andrew


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