Truma Combi 6 (gas only) no hot water

[andy b]

hi,

new to caravan forums, but been struggling to find any answers or thoughts regarding an issue I'm having.

I have a 2024 hobby (Import) which has truma combi 6 gas only source which seems to be having a dickie fit.

i can run blown hot air up to the desired temperature and the system nicely maintains this temperature. but when i try ask for hot water i only get a small amount and then nothing. ( presume small amount is due to water being heated as the heating is running.

if i switch off the heating and just set up for hot water, after a minute boiler kicks into life fires and then stops after a minute. (no hot water to tap) when hot tap running boiler will not fire as i would normally except.

i have no error messages showing up on truma cp plus panel.

Gas is fine, 12 volt electric are working (brand new 110ah AGM battery).

any help or useful suggestions would be gratefully received.

 

[Martin_E]

Presumably you have purged all the air out of the hot side of the water system?

What setting have you set for the water?

If you set the water to boost does the boiler respond?

 

[andy b]

hi,
All the purged from the system.
i have tried all settings for the water, Eco, Hot and boost.
boost will fire up the boiler after 1min aprx and run for aprx 1 min before shutting down.

on reading more i have discovered that this unit is not instant heat and will not fire on demand of hot water so that clears that side of query, but i should in theory still be able to heat 10.5L of hot water without the need of heating too.

 

[Martin_E]

Yes, not instant hot water, probably 40 + minutes to heat up the water when it’s not cold outside, longer when running heating as well.

 

[andy b]

thanks for your response, just have to be more patient then

 

[Martin_E]

Possibly 🤔

 

[IanB1485]

There is a thermistor sensor which measures the hot water , the hot it gets the lower its resistance , however if open circuit or damaged the controller may be getting false info about the water temperature. the gas is 6kW( not 4 as in the 4E) and the water jacket contains about a litre of water so it should warm up pretty quickly

 

[Martin_E]

the water jacket contains about a litre of water so it should warm up pretty quickly

Really

I believe it holds 10 litres 🤔

 

[andy b]

Thanks Ian, I will try and locate the thermistor and put a tester on it later today / tomorrow and update.

 

[Hutch]

I believe there are two temperature settings , 40c for " summer" and 60 c for winter,

 

[IanB1485]

@Martin_E yes my mistake 10 not 1 , slip of the electrons, The spec says it should achieve 60 degs in 20 minutes -boiler only , but the spec only states that for all models (2E, 4E & 6E) which is odd as the calculations show that it would take about 17 minutes for the 2E , 9 minutes for the 4E and 6 minutes for the 6E. of course that does not take into account warming the supply pipes up once you turn a tap on.Diving deeper into the installation /operating instruction it states that in hot water mode the gas burner runs at the lowest setting which for the 6E is 2kW so back to 20 minutes for initial warm up