Truma Combi 4 Question (1 Viewer)

[Falcon 269]

Undoubtedly a numpty newbie question but I'm sure some kind soul will take pity and put me straight.

Simple one, really - we took off on our maiden MH voyage this weekend and had a brilliant time up until the moment when the Soup Dragon tried the shower. It went from hot to cold in a heartbeat - even though we have a pistol grip shower head - causing much consternation from within the cubicle. I didn't laff much, honest ...

Anyway, the unit is a Truma Combi 4 gas-only job, with a Truma Classic control unit. We'd turned it on the day before on arrival on site and set it to 40c on water heating only. We had hot water for washing up etc the day before and I assumed that the boiler would have automatically refilled and reheated to the set temp ready for use this morning.

So, am I right in thinking that Truma combi boilers are a constant heat-on-demand type, or does the control knob have to be switched off and back on again to heat each boiler-full individually. I find it hard to think it's the latter but the manual isn't clear on this.

Incidentally, after SD's cold shower experience, I was told to try it for myself. Temp gauge set to 60c, waited until the orange light went out and had me a lovely warm shower throughout. That didn't go down too well, as you'd imagine.

Thanks in advance.

 

[peterc10]

As long as it is switched on it will heat the water in the tank. But it is not an instantaneous heater. It keeps a tank full. i.e. 10 litres, hot. If you take too long showering it will go cold on you. You need to master the technique. Quick spray of water all over, switch off. Soap up everywhere (we find body lotion is better than a bar of soap). Then turn on and rinse off. Uses a lot less water.

 

[Tootles]

We tend to keep ours switched to 'max'. It cuts out when it gets there anyway. You can make the very hot go a damned site father letting it down with cold. :thumb:

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[TheBig1]

your problem is that if you only heat a few litres to 40degrees then it will quickly be used up, and faster than the boiler can cope with. its not on demand instant heating, it is more like an old fashioned immersion heater at home, but only 10litres

switch the heat setting to max and use a little bit of hot water with more cold to set the temperature. remember too, its not like a house shower, water in a van is a limited resource. a sailors shower works best. get wet, switch off water, soap, then water back on to rinse

when done right, 3 people can go through the shower in our van without the water going cold or running out. i remember well the small aquarolls that used to be a normal water supply, where somebody always had to get another between showers. they were only 28litres. teaches you to find a good solution very quickly too

btw, not a numpty question, we all have to learn this stuff as we go along:thumb:

 

[Falcon 269]

Thanks everyone. :thumb:

Your replies confirm what I thought, which is that the boiler should be automatically heating the cold water being drawn in to replace what's being used through the shower or taps. I realise that it is not as fast as a domestic on-demand boiler, obviously.

We were using the 'sailor's shower' technique - hence the pistol grip shower head to replace the original one - but the SD reports that the water was cold almost from the moment she started her shower. This is what threw us ... there had been ample time for the boiler to have heated the full 10 litres to 40c before she started and the absence of the orange light on the control knob confirms this.

I think that 60c needs to be the default temp in future but no doubt I'll be shoved in to the shower first next trip to prove the theory!

PS. Edited to add one more question. As cold water replaces the hot, should the orange light on the control knob come on to indicate that the water temp has dropped below 40/60c and then go out again when it's up to the set temp? If so, I don't recall ours doing this.

 

[Tootles]

The water temperature sensors are not all that sensitive, and in warm weather, at 40c, the thing probably isnt firing up. Also, if you have water in your supply tank that has had the chance to reach a decent temperature..........
Stick it on max, best policy, and in summer it uses very little gas anyway.
Not sure about the orange light, ours just has the green for working, red for inop.

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[peterc10]

Not sure on the light. Mine is gas and electric Combi 6E so has two switches, whereas I guess yours only has one that chooses hot water at 2 temperatures or heating or both and also dials in the temperature for the heating, My one of those has a green light that stays lit when it is on and a yellow light that comes on when it is in "boiler heat-up phase". They should light up together and the yellow one switches off when the selected temperature is reached. .

 

[Falcon 269]

Not sure on the light. Mine is gas and electric Combi 6E so has two switches, whereas I guess yours only has one that chooses hot water at 2 temperatures or heating or both and also dials in the temperature for the heating, My one of those has a green light that stays lit when it is on and a yellow light that comes on when it is in "boiler heat-up phase". They should light up together and the yellow one switches off when the selected temperature is reached. .

Thanks, you guess right about the operating modes of our gas-only Truma 4. We have green for 'on' and orange for our 'boiler heat up phase'.

Tootles, what you suggest may well be the case. I'll be using 60c from here on.

Off to have practice shower before Wanda is taken back to the pound.

 

[Falcon 269]

I always try to follow-up a subject to complete the circle ...

First 'practice shower' consisted of heating one tank of water from cold to 40c. It took 15 mins and when the tap was run until cold water flowed, the orange light remained off, suggesting that the boiler thermostat was not kicking the burners back online.

Second 'practice shower' was to 60c and that took 20 mins. More to the point, when the boiler was drained, the orange light came on immediately and the boiler fired up.

Clearly I'll be using 60c as the default setting from here on but I'd like to know for sure if the thermostat is supposed to fire up the burners automatically on the 40c setting, too.

Anyone else have experience of this particular model of Truma?

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[Davesetts]

Hi got our new MH last Oct and have similar issues with gas only combined when heating water. On switching on the green and amber lights come on, water heats to chosen setting(40 or60C) and amber light goes off. But, if hot water then used up, boiler does not restart, amber light remains off and the only way to get it to heat more water into switch off altogether, wait a couple of minutes then with back on. Green light then amber light both come on, boiler fires up and soon we have a fresh supply of hot water, amber light going off when chosen temp is reached. I have asked dealer to check and advise if this is correct (to prevent wasting gas maybe?) or if boiler should restart automatically to reheat water as it is used...which is how the electric system worked in our old caravan..I'll see what dealer says as we also have problem of pressure relief valve operating frequently and dumping lots of water! Not sure if its valve (been changed once already) or pump running on too long and over pressurising system.

 

[Davesetts]

Oops gas only Combi!!!!

 

[Davesetts]

Had response from dealer, apparently truma control unit is faulty...we'll see how it behaves with a new one!

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[TeeCee]

Anyone get a 'rubbery burning' type smell when Truma Combi is on?