Too much hot water

I don't think that you can turn off the hot water if you are running the heating in your caravan, although I have been known to be wrong. 

Might need to know a bit more about the system you have and age? If you have  a Truma set up with a CP panel the heating and hot water are separate. Is it possible the hot water has been left on by accident? Even on the old Truma systems (round dials and lights) it was possible to control heating and hot water separately. 

David

You could try turning the blown air fan off to see if that helps

In some systems the hot water tank surrounds the heater element so if the heating is on, so is the hot water but I agree with David in that we need more info.

The Truma combi boiler in our MH will produce reasonably hot water, after a period of time, with just the blown air  heating on. Of course if the heating turns off the water will gradually cool unless water heating is separately selected.

We have the Truma Combi 6e in our van and I've noticed that regardless of whether the hot water is turned on, the water gets warm with just the heating on.  It's particularly noticeable if you're running on gas - when it gets really hot relatively quickly.

I don't see it as a problem and don't understand why the OP wants to 'turn it off'?

What I will say, though - is that it's best to run the heating / hot water on gas whenever you can.  I know to my cost that with, admittedly, fairly heavy usage of our van, the electric heating elements only last about two years and when they failed again this February - almost two years to the day after they were last changed - it cost me over £700 for them to be replaced.

Wow!!!£700, cant beat the old system simple cylinder gas/electric, electric is just a simple element inside the water cylinder, ours failed in Spain a couple of years back 30 euros for engineer to replace, never used the gas, heating in caravan is via gas/electric fire blown air works just fine,   

Our Truma heating system in our MH, gas/electric is 22 years old. We have had MH 10 years now, never had a problem with heating or hot water. Work separately. As far as we know (got lots of paperwork about it’s previous life) it’s never had a problem. We use it for both heat and water, and use it daily as we often off grid.

Hope the OP gets their issue solved, and it’s not expensive. 

I agree, between Truma and van designers they have made things unnecessarily expensive. Truma will now only sell a complete heating unit, rather than the elements and Hymer saw fit to shoe horn our boiler into a position where it had to be removed to replace them. Ours lasted 4 years.☹️

I think the problem with costs is that Truma only supply the complete heating cassette and no longer the elements. (I understand these can be obtained by third party suppliers but that is always likely to be a risk?) Truma in Derby will actually carry out  the work if its easier than going to a dealer. 

I am trying to visualise the system mentioned by TDA. If I recall the was a stand alone heater, including fan and a separate boiler, not unlike the current Combi but without the blown air connections. Before that it seemed to be just a Carver convector heater and a Cascade boiler for hot water. I think Carver was taken over by Truma.

David