# Truma heating & hot water



## changabang (Oct 7, 2006)

Hi folks, wonder if anyone can help. I recently purchased a Renault Master Devon conversion fitted with a Truma Combi 4E or 6E don't know which as I can't get to see the label on the unit because the surrounding 'build in' obscures it. Anyway this unit has a frost sensative valve which pops out when the temp drops to 3 degrees and empties the unit of water. Fine I can understand that. What I can't get my head around is the fact that you can't push the valve button back in till the unit warms up to 7 degrees. Consiquently, as far as I can tell, you can't use your onboard water system because the water heater (which now has it's frost safety drain valve open) tries to fill up at the same time thereby allowing your pumped water to empty straight outside???? Is this making any sense???

I know you can get a winterising gizmo (which I ordered some time ago) to heat things up, but not to be able to use your cold water system because of of a frost protection valve poping out seems a bit bizzare.

Is there a work around to this? Anybody else go one of these untis?


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## Boff (May 10, 2005)

changabang said:


> Is there a work around to this? Anybody else go one of these untis?


Yes, there is: _First_ switch on the heater, _then_ close the safety valve.

BTW, no harm can be done, it is designed to run with or without water.

Best Regards,
Gerhard


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## changabang (Oct 7, 2006)

Thanks Gerhart,

I'll give it a go!

Chris.


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## Steamdrivenandy (Jun 18, 2007)

We picked up our new Adria last Thursday with one of these units.

I assume the temperature sensor for the drain valve is in the drain unit itself and not somewhere remote on the van. If it is in the unit then provided the boiler/heater is switched on I'm certain that ours will be kept above 3 degrees. Over last weekend, with boiler only switched on, it was real toasty warm in the rear garage where the unit sits.

So that's OK for when you're pitched up and I guess it's prudent that in v cold weather it would auto drain when either parked out of use or in transit.

As you suggest though the problem comes when you're out in chilly weather with an empty water system and you want to fill up again. As Gerhard says you can run the unit as a warm air heater only and given my experience of the heat given out in the area around the Truma I suggest it would soon be way above 7 degrees and therefore would hold a fill. 

This is all 'in theory' as we, like you, haven't had a chance to try it out in practice.

I do recall some earlier threads which talked about using a clothes peg to stop the drain valve operating in weather that was cold but not going below freezing. Perhaps someone with actual experience of the Truma might clarify for us?

SDA


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## Rapide561 (Oct 1, 2005)

*Truma 6E*

Hi

I too am using this boiler but this will be my first "winter season" with it. I suspect that I will not need to peg anything as the heating is always on.

My gut feeling at this early stage though, I preferred the Truma C6002 EH - ie the predecessor!

Russell


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## Spacerunner (Mar 18, 2006)

It just occurred to me, what happens if you are driving in sub zero temperatures with a full water heater. The gas system turned off and the frost stat sensative to outside temperatures, which is going to be exaggerated due to wind chill factors.
Will the water heater just dump as you drive?


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## Rapide561 (Oct 1, 2005)

*Boiler*

Hi

Very good point - but I suspect the temperature sensor is somewhere inside the motorhome, near the boiler.

I have never dropped my boiler contents what ever the weather.

Russell


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## Telbell (May 1, 2005)

> Will the water heater just dump as you drive?


Presumably yes-though with more modern vehgicles which have the "securemotion" type of Gas system you could keep it on a low temp whilst travelling to prevent this.


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## greenasthegrass (Oct 27, 2007)

We travel with ours switched on to keep the boys and dogs warm in the back this prevents ours dumping although when it was -5 in Ravenglass in February the gas bottle ran out and before we could change it to the other one Drew opened the garage to get his tool out to do it and that set off the dump valve fortunately pushed it back in and shut the door and it was ok.

He now keeps the gas tool thingy in the gas tool placey in the gas locker!

Greenie

PS its a boy job am a girl I wouldn't know! :lol: :wink:


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## changabang (Oct 7, 2006)

*Truma*

Looking at the user manual for this unit the "Frost Control valve is a currentless safety/drain valve." Which I guess means when it gets a chill it 'dumps'. Don't think temperature sensors bit comes into the frame it's all built into this valve. Unless we keep the thing warm it's going to dump, hence the add on heater thingy Truma sell (if you can get hold of one!). What I'm still hazey about is how do you get your water system pressurised when the valve is open as every thing passes through the unit which wants to fill up first but can't because it's dumping on the way through. Hence no pressure in the system to sink taps???? I can live without hot water but I'd like some cold coming out of the taps when the temp is 3 degrees. Or is my pea brain still missing something here??

I haven't started on the 'heater thingy' you can add to the unit to keep the valve warm. What sort of drain on the leasure battery might that be?


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## Boff (May 10, 2005)

Steamdrivenandy said:


> I assume the temperature sensor for the drain valve is in the drain unit itself and not somewhere remote on the van.


Nope, the sensor is in the drain unit itself. And as soon as you turn on the heater, it will receive a signal that will override the sensor, and enable you to close the valve, no matter the temperature.



Rapide561 said:


> My gut feeling at this early stage though, I preferred the Truma C6002 EH - ie the predecessor!


I have already seen the Combi, and there are not too many differences to the Trumatic C: The whole unit is now not in upright but horizontal position, it is even more insulated, the burners are a little stronger, and the boiler is a little smaller. But otherwise it is the same (in my opinion ingenious) design.



Spacerunner said:


> It just occurred to me, what happens if you are driving in sub zero temperatures with a full water heater.


No problem, as long as the temperature at the drain valve does not fall too low. As said, the sensor sits inside the drain valve unit.

In most MH the drain valve is located in the same locker as the heater itself, so after a decent heating session in the morning before departure it will be warm enough for some hours, even if the van is not heated. I have however once had a hire van - in winter! - in which the manufacturer (well-known brand!) had placed the drain valve far away from the heater in an outside storage locker. Now guess what happened... :evil:

Best Regards,
Gerhard


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## geraldandannie (Jun 4, 2006)

I used the peg thing last winter, although when laid up, the van has a mains-powered, oil-filled rad to keep the chill off. The bioler and dump valve are inside the van, under the bed.

Unbeknownst to me, the MCB on the outside mains feed tripped, and the heater went off. Fortunately, there was no damage because the valve had dumped anyway, 'pinging' the peg off :roll: 

When we've been away in it, we've never had the valve dump. We either have the heating on, or it stays warm enough during the day when we're out and about.

Incidentally, it is a good tip to turn the water pump off whenever you leave the van, just in case - better to lose one boiler full than a whole tank :wink: 

Gerald


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## changabang (Oct 7, 2006)

Thanks Gerhart,

Things are starting to make sense at last!

Chris


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## Steamdrivenandy (Jun 18, 2007)

Thanks guys, like Chris it's all starting to make some sense now.

I take it from your remark Gerald that if the pump is 'on' it'll carry on pushing water through the boiler 'til it empties the tank, but if the pump's off it'll only drain the boiler. Good tip as our fresh tank is inboard and relatively safe.

SDA


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## geraldandannie (Jun 4, 2006)

Steamdrivenandy said:


> I take it from your remark Gerald that if the pump is 'on' it'll carry on pushing water through the boiler 'til it empties the tank, but if the pump's off it'll only drain the boiler. Good tip as our fresh tank is inboard and relatively safe.


Yup - same as ours.

Of course, using the peg does have some risks associated with it, and if there is any danger of the area around the boiler dropping towards freezing, let it dump.

When the van is laid up, I lift the bed up to allow the warmer air from the rad circulate around it a little.

Gerald


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## changabang (Oct 7, 2006)

I notice from my user manual 'if only the cold water system is being opperated, without using the water heater, the heater tank also fills with water (yup we get that now!). To avoid frost damage, the boiler must be drained through the drain valve (fair enough!) even if it was not operated. As an alternative (here we go) two shut off valves resistant to hot water, can be fitted in front of the cold and hot water connection'. This I guess isolates the boiler. 

Are we to assume that if one did this retro fit (which might be useful if ever the boiler 'went down') we would still get a pressurised cold water system?


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## sideways (Jun 2, 2008)

Doesnt matter whether the pump is on or not it will syphon all the water hot and cold. My leisure battery went down at Pickering show when i disconnected it to change it, the valve opened and dumped all the water, it wasnt pumped as there was no battery.


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## Steamdrivenandy (Jun 18, 2007)

sideways said:


> Doesnt matter whether the pump is on or not it will syphon all the water hot and cold. My leisure battery went down at Pickering show when i disconnected it to change it, the valve opened and dumped all the water, it wasnt pumped as there was no battery.


Ooh, that not so good


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## Boff (May 10, 2005)

sideways said:


> Doesnt matter whether the pump is on or not it will syphon all the water hot and cold.


To avoid that, not only switch off the pump but also open all water taps. Then, if the dump valve opens air will rush into the system through the taps, and the water in the cold tank will stay where it is.

BTW, this also protects the taps themselves against frost damage. As I have learned the hard way... 

Best Regards,
Gerhard


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## 114677 (Jul 22, 2008)

*Truma heater problems*

Hi , I have a similar problem with my Truma heater . I tend to hold the valve in the closed up position with a peg . This stops the water dumping at low temperatures . I have heard that it is a design fault by Truma but I dont know of the manufactures way to correct it . I guess they would have to alter the electronic control board . You will have to be careful in very cold temps because you might get frozen pipes etc , luckily all mine are well insulated . This will also happen if the supply fuse to the 12 volt electric blows as happened to myself in previous post , please read if you can for full explaination . _(Mod Edit . . . possibly libellous comment deleted.)_
Rgds.........Joe97


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## premiermotorhomes (Feb 13, 2008)

The Truma Automatic Dump valves are designed to dump the water when the battery levels drops; the valve is designed to operate in this fashion before whilst there is still enough power to operate the valve. Also when the temperature gets close to freezing, I can't remember the exact value.

In both cases this is designed to stop water freezing in your pipes, as the expansion from water to ice can damage your water system.

These steps are in place to protect your vehicle, so I wouldn't reccomend making any alterations to the system; on a new vehicle you may void your warranty and any claim thats raised due to a frozen water system as a result of a modification will likely be rejected.

I hope this helps clear the matter up.

Regards,
Chris
Premier Motorhomes of Chichester


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