Too much hot water

Not far off DK. Stand alone heater, under wardrobe, but there are blown air outlets into bathroom and around living area, so it can be just heater alone, or use blown air as well. Water heater tank is under one of beds. Both work fine either on gas or hook up, and have thermostats.
Our old caravan has Carver branded heaters. OH has put in a new (to us) heater, again under wardrobe. This works on either gas or hook up, but no blown air system. Replacement water heaters are harder to find, but we have one, but only use it on hook up. Van is 40 years old this year. Our larger van, another Cotswold dating from 1984 had Alde heating. A tall heater/tank system at side of wardrobe, with pipes all around under seats/beds, into bathroom. We didn’t like it, nowhere near as warm as Truma/Carver, took ages to get warm. But you did get warm clothes, most efficient inside wardrobe🤣

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.

In our 2004 Abbey we had a Truma convector heater, which also supplied blown air to a couple of vents. It kept the van toasty warm even on 900 watts. It worked faultlessly on electric for 8 years, when sold it.  The water was supplied from a separate mini immersion heater, which also performed faultlessly.

Sounds very like ours Steve. Simple set up really, easy to use, easy to fix should anything go wrong. I suppose the more high tech things become, with computers running things, the less reliable, harder to fix and much more expensive things become. Bit like modern cars I suppose. We can hit the MG with a hammer to cure faults, Jeep needs linking up to diagnostics, then your wallet takes a hammering🤨 

Very rarely do we turn the hot water on. When the blown air is on there is enough heat in the combi to heat the water too. It does, however, take a longer time to warm up. We only turn the water heater on in summer when no space heating is required and only then for short periods when hot water is needed. It heats up quickly mind, particularly on gas and, I think, it’s set at 60C.

 Correct David - re the heater elements.  The problem was that if the elements weren't fitted properly (i.e., the fins crimped around the element) they went in no time at all.  Experienced that when the dealer didn't do the job properly two years ago and the elements only lasted a month! Truma obviously had a major problem and that's why they then only sold the elements as a 'kit' which included the elements already fitted into the heating cassette.  That's what was subsequently fitted but they still only lasted two years.

They've also changed the design of the gas burner and some of the gaskets - whether this will make a difference, only time will tell.

There was a lot of discussion about this on 'Caravan Talk' and someone had calculated the number of hours an average element would last.  I worked that out against our usage of the van and it equated to about 18 months use - so in one sense, we did well to get another six months use out of it.  It's still absolutely ludicrous, though.

I agree with Rufs - why can't they be made with a simple domestic-type immersion heater element which costs £20 or so?

There was talk, some time ago (according to our dealer), that Truma were discontinuing the Combi 6e and replacing it with something more reliable but that doesn't seem to have materialised.

When we are away in the van we don't experience what the OP does as the hot water and heating are always on together. Obviously when its warmer we will just have the hot water on. The only time the heating is on by itself is if we are trying to warm the van up to give it a bit of an airing over winter when the water system is empty.

David

"I agree with Rufs - why can't they be made with a simple domestic-type immersion heater element which costs £20 or so?

because as the years have rolled by more and more caravaners/MH people wanted to walk out of their house into the caravan or MH and have exactly the same creature comforts as they have indoors and these come at a price and some major downsides e.g. trying to squeeze a quart into a pint pot means some stuff is installed into very tight spaces and when it goes wrong you need to take the caravan/MH to bits to effect any kind of repair.

We use our hot water heater simply because it is more convenient for us to wash up in the van, for heating we have the inbuilt fire/blown air but normally use a blow heater fan sitting on a shelf much more efficient and much eaiser to control.