Truma Combi (E) - hot water fail overnight

[Andy MacD]

Hi there, looking for some help please with an intermittent issue with hot water while on electric hook up.

With the heating and hot water on high we are occasionally waking to no hot water. The control panel doesn’t show any error messages, just the hot water indicator flashing to suggest the water is heating up. The overheat button on the boiler hasn’t triggered. Turn the hot water off and on again at the control panel and it starts heating again.

This has happened 5 nights out of 8 while away on 2 different sites and we resorted to turning the hot water off at night and back on first thing then waiting for it to heat up for showers etc. Why it worked the other 3 nights we have no idea but rules out site electric supply.

Testing on our driveway I turned the hot water on at 17:30. Checked at 18:45 and temp was 60 degrees at the tap. At 22:00 it was 65. Checking following morning at 09:30 temp was 69 degrees and still at 69 at 12:30. Not tested hot water on eco setting as in real life we would never use at that setting.

Manual says hot setting on electric is 60 degrees and 70 on combination and gas. Can’t see any way to adjust water temp setting.

I suspect that the boiler is overheating the water, could it be higher then 69 with the heating on as well? As it overheats the boiler thermostat cuts in but doesn’t re heat as the water cools. Dealer has no idea and wants to take the van in under warranty.

Trouble is like any intermittent fault they could have it for a week with no issues showing.

Has anyone else experienced this, if so what was the fault and solution?

Thanks.

 

[David and Sally]

We find if we have the heating on overnight the water is only just warm in the morning. This is on ehu, no gas. It seems the system prioritises the heating and not the water.
We just boost the water for half hour in the morning.

 

[DavidG58]

With the heating and hot water on high

can’t help with the fault , but could it be you should not leave it on hjgh ?

we have Alde heating and that has a hot water boost but it self timed out if used

 

[Andy MacD]

Thanks David and Sally . This is a new van so my comparison is the Benimar we had for 2 years with same kit and never had this issue.

DavidG58 , having it on eco means not enough hot water for swmbo after I have my shower, not a good way to start the day!

 

[Cheshirecat57]

Dont believe you can alter the water temp....its HOT or NOT
On our Twin we used to just BOOST first thing, hot in 20 mins post 1st brew

Happy twinning.....

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[Lenny HB]

The Eco setting on the C6 is unusable due to the large hysterises, thermostat turns off at 40°and does not turn back on until the water temp drops below 27°.

Hot water is a pain generally on the C6 it takes far longer to heat up than Truma claim, about 40-45 min just on hot, if you have heating and hot water it takes over an hour for the water to get to temp, just running the heating the water takes over 1½ hours to get hot.
When on boost the heating turns off until the water is up to temp. If I want hot water for a shower and get up to a nice warm van at 8:00, I set the timer to turn on at 7:00 heating set to the temp I want and water on boost. Then it will turn on at 7:00 and heat the water until about 7:45 then the heating will turn on.

As for the fault have you tried running on gas only, if it still does it, it would point to an electronic fault on the pcb.

 

[Andy MacD]

Thanks Lenny HB , not left on gas overnight.

See you point re timer, my view is a paid for something to work as advertised and stated in its operating manual so that’s what I expect.

Having run the same system on another van for 2 years I see no reason why my new one won’t do the same.

 

[David and Sally]

Thanks David and Sally . This is a new van so my comparison is the Benimar we had for 2 years with same kit and never had this issue.

DavidG58 , having it on eco means not enough hot water for swmbo after I have my shower, not a good way to start the day!

I think Lenny HB has better expressed what we get on our 6 and what I was trying to say.

 

[Lenny HB]

I think Lenny HB has better expressed what we get on our 6 and what I was trying to say.

My experience is only on gas I've never had a Motorhome with the electric option.

 

[David and Sally]

My experience is only on gas I've never had a Motorhome with the electric option.

It’s worse on electric. To get max heat and water we have to use the Mix 2 of gas and electric. Elec only is poor, gas only is poor too.

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[Lenny HB]

It’s worse on electric. To get max heat and water we have to use the Mix 2 of gas and electric. Elec only is poor, gas only is poor too.

It's just the hot water that's naff the heating works a treat much better than the older C6002 but that was superb on hot water you could set it to 40 deg and it would be fine for 2 showers.

 

[G-RMPS]

From memory the boiler capacity is around 10-12 litres. At the higher electric setting the heating element is 1.8 watts. So not much more than half a domestic 3kw kettle or the heating element in a domestic water tank. I’m not surprised it takes 45 minutes to heat that volume of water to 60 degrees. I think the calorific output of the gas option is 2-3 times that of the electric heating.