Ideas to improve Truma therm output and capacity

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Hi all just wondering if anyone has experience of upgrading the small ( 5litre) hot water capacity of the Truma therm? This is installed in my new knaus deseo but is really not sufficient for showering or washing up. Could I replace with a larger gas/ electric heater or add a second heating appliance located in a suitable cupboard space to work alongside the therm?
sorry if this has been asked and answered already elsewhere
Thanks
Tom
 
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I recently posted the following in the topic “heated aquaroll”. You may want to read it all. If I felt I had your problem it is what I would have done.

********

I have a suggestion which could be used as well as or instead of that idea. Someone on another forum has made one of these and says it works well. Having studied it I can’t fault it. Personally I decided not to bother as we are happy with our quick shower routine.

So here it is (as far as I can remember).

It will work with Truma or Alde. It needs an extra tank some pipe, a non return valve and a small pump. Hot water is circulated from the existing hot storage tank, through the new tank. The temperature is therefore controlled by the existing sensors.

But the hot water storage can be doubled, or more.

I know that’s not a full explanation. But I will try to find his drawings and post them here.

John

OK. I have found it. Not mine, just copied from another forum. Quote.


60ECBE65-FFE7-49DE-A110-6BCA8A185FCD.png



“This is my system, the new tank was stainless steel, insulated with polystyrene tiles (about 25mm thick), the pump was from ebay - Brass bodied, doesnt need massive power, the one way vale and 't's came from a caravan shop. I do have a drain port on the new tank for draining down.



The way it works, when you want the additional hotwater, switch new pump on and water circulates round the water heater and the new tank, the existing water heater heats up the water when its done you have xx litres of additional hot water, switch off the pump and enjoy your shower! When you dont need the additional hot water turn off the pump and the additional tank will then just be full of cold water. Dead simple, nothing complicated, the size of the additional tank can be made to meet your needs ive had a 10 litre and now have 20 litres. A local sheet metal company made my second tank to my drawing and it cost £37 in stainless steel. The first one was from ebay and cost £7. 50! The pump was from memory about £35.“


**********

John
 
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Damian

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Hi all just wondering if anyone has experience of upgrading the small ( 5litre) hot water capacity of the Truma therm? This is installed in my new knaus deseo but is really not sufficient for showering or washing up. Could I replace with a larger gas/ electric heater or add a second heating appliance located in a suitable cupboard space to work alongside the therm?
sorry if this has been asked and answered already elsewhere
Thanks
Tom

The Therme is a very small capacity water heater, which as you have found is not capable of any prolonged hot water use such as a shower.
You could get it replaced with a Truma Ultrastore or similar if you have room where the Therme is now but of course it will need fluing to the outside, so a hole in the side of the van, and the pipework will need reconfiguring to match the new heater outlet and inlet.

It would be very advisable to have this change done by a qualified person to maintain warranty, and ensure the safe fluing and gas connections.

The advantage of going for a dual fuel heater is that you will not have to have mains power to heat the water as you will have gas as well.
 
Last edited:
Oct 12, 2020
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15
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I recently posted the following in the topic “heated aquaroll”. You may want to read it all. If I felt I had your problem it is what I would have done.

********

I have a suggestion which could be used as well as or instead of that idea. Someone on another forum has made one of these and says it works well. Having studied it I can’t fault it. Personally I decided not to bother as we are happy with our quick shower routine.

So here it is (as far as I can remember).

It will work with Truma or Alde. It needs an extra tank some pipe, a non return valve and a small pump. Hot water is circulated from the existing hot storage tank, through the new tank. The temperature is therefore controlled by the existing sensors.

But the hot water storage can be doubled, or more.

I know that’s not a full explanation. But I will try to find his drawings and post them here.

John

OK. I have found it. Not mine, just copied from another forum. Quote.


60ECBE65-FFE7-49DE-A110-6BCA8A185FCD.png



“This is my system, the new tank was stainless steel, insulated with polystyrene tiles (about 25mm thick), the pump was from ebay - Brass bodied, doesnt need massive power, the one way vale and 't's came from a caravan shop. I do have a drain port on the new tank for draining down.



The way it works, when you want the additional hotwater, switch new pump on and water circulates round the water heater and the new tank, the existing water heater heats up the water when its done you have xx litres of additional hot water, switch off the pump and enjoy your shower! When you dont need the additional hot water turn off the pump and the additional tank will then just be full of cold water. Dead simple, nothing complicated, the size of the additional tank can be made to meet your needs ive had a 10 litre and now have 20 litres. A local sheet metal company made my second tank to my drawing and it cost £37 in stainless steel. The first one was from ebay and cost £7. 50! The pump was from memory about £35.“


**********

John
Many thanks I’ll keep this in mind. I am also looking at a straight replacement for a bigger thermastor heater if affordable and enough space in the van
 
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Oct 12, 2020
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The Therme is a very small capacity water heater, which as you have found is not capable of any prolonged hot water use such as a shower.
You could get it replaced with a Truma Ultrastore or similar if you have room where the Therme is now but of course it will need fluing to the outside, so a hole in the side of the van, and the pipework will need reconfiguring to match the new heater outlet and inlet.

It would be very advisable to have this change done by a qualified person to maintain warranty, and ensure the safe fluing and gas connections.

The advantage of going for a dual fuel heater is that you will not have to have mains power to heat the water as you will have gas as well.
Great thanks yes I am looking at professional installation possibly replacing the therme with ethe bigger ultrastore
Appreciate the advice
 

JTQ

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Put a second one inline?
Saves dumping what you have and the major hassle to best exploit the Ultrastore of introducing the gas vent supply etc as already flagged up. You end up with the same usable capacity as the often used 10 litre version of the Ultrastore.
The Ultrastore gas vent comes with strictures on its position with respect to openning like windows, so far from issue free.
 
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Put a second one inline?
Saves dumping what you have and the major hassle to best exploit the Ultrastore of introducing the gas vent supply etc as already flagged up. You end up with the same usable capacity as the often used 10 litre version of the Ultrastore.
The Ultrastore gas vent comes with strictures on its position with respect to openning like windows, so far from issue free.
Thanks yes doubling up is certainly an option and might be simplest. The ultrastore does give the additional benefit of either or both gas and 240v. Which could be very useful if wanting water heater quickly or when not on a serviced pitch. I’ll find a local specialist fitter to check out labour costs etc. as cost will play a part in th decision. Many thanks
 
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Oh well!! Turns out that it is not possible to find a suitable sized space to replace my existing truma therme water heater anywhere in my knaus Deseo. Main dealer plus 2 motorhome conversion folk concur that it isn’t possible. The existing space under the sink where the therme is installed is too small for the larger ultrastore, the adjacent underbed drawer space is also ruled out due to lack of access to an outside “wall” and because the bed slides out.
so adding another heater can’t be done either for the same ( lack of space) reason. Could the chap (John)? who provided the description of adding a second in line tank give me a link to the forum he saw it on?
I’ve thought about a low wattage instant shower and a portable camping gas shower/ water heater often used for washing horses etc but the latter looks way too big to cart around or plumb in to my small van.
And of course any other creative ideas welcome.
Thanks
 
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Oh well!! Turns out that it is not possible to find a suitable sized space to replace my existing truma therme water heater anywhere in my knaus Deseo. Main dealer plus 2 motorhome conversion folk concur that it isn’t possible. The existing space under the sink where the therme is installed is too small for the larger ultrastore, the adjacent underbed drawer space is also ruled out due to lack of access to an outside “wall” and because the bed slides out.
so adding another heater can’t be done either for the same ( lack of space) reason. Could the chap (John)? who provided the description of adding a second in line tank give me a link to the forum he saw it on?
I’ve thought about a low wattage instant shower and a portable camping gas shower/ water heater often used for washing horses etc but the latter looks way too big to cart around or plumb in to my small van.
And of course any other creative ideas welcome.
Thanks
If you search posts by Grey13 he designed and built a system using external supply and an auxiliary heater to give him longer in the shower. I gather it was a success.,

This should get you started.
https://forums.practicalcaravan.com/threads/aquaroll-heated.55804/


You can PM members too if required for in depth discussions.
 
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Oh well!! Turns out that it is not possible to find a suitable sized space to replace my existing truma therme water heater anywhere in my knaus Deseo. Main dealer plus 2 motorhome conversion folk concur that it isn’t possible. The existing space under the sink where the therme is installed is too small for the larger ultrastore, the adjacent underbed drawer space is also ruled out due to lack of access to an outside “wall” and because the bed slides out.
so adding another heater can’t be done either for the same ( lack of space) reason. Could the chap (John)? who provided the description of adding a second in line tank give me a link to the forum he saw it on?
I’ve thought about a low wattage instant shower and a portable camping gas shower/ water heater often used for washing horses etc but the latter looks way too big to cart around or plumb in to my small van.
And of course any other creative ideas welcome.
Thanks

Thought that might be difficult as I was“BANNED’’ from that forum. My virus company added an ad blocker without my knowledge. Despite them apologising to the forum I remained banned. But I now run a VPN. But not interested in rejoining due to their intransigence. I now look and I my statues seems to have moved from banned to ‘no longer a member’. Their loss.


Here is a link to that topic. Somewhere on that site is a very detailed version.

As I remember, the person who did it also did it on a previous van. It utilises the existing gas and electric heaters, simply increases the quantity of hot water available for use. Size would depend on how big the added tank is. I think the person had a stainless steel tank purpose made.

It would certainly be my choice if I needed more hot water.


John
 
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Mar 14, 2005
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Hi all just wondering if anyone has experience of upgrading the small ( 5litre) hot water capacity of the Truma therm? This is installed in my new knaus deseo but is really not sufficient for showering or washing up. Could I replace with a larger gas/ electric heater or add a second heating appliance located in a suitable cupboard space to work alongside the therm?
sorry if this has been asked and answered already elsewhere
Thanks
Tom
Hello Tom
I have just looked up the specs of the Deseo and Apparently you have a Truma VarioHeat which seems to be a more recent version of the their older E series heaters. This now makes more sense to have Trumatherm, but even so the Therm only holds 5L of hot water, but if that is at 65C, then when its mixed with cold water it should be enough for about 1 quick shower.

The Threm only has a 300W electric element, and that by its self will take about over an hour to heat up 5L from cold. It s difficult to know how effective the TrumaTherm is at recovering heat from hot air blowing through it Heat transfer from air to water is usually quite poor so whilst it will help - a bit it's not the best way of heating water.

I can see from the knaus catalogue there isn't much space available to to change things.

Just considering the second tank idea, if you are relying on the Trumatherm to heat it all, 300W is going to take a long time to get it all up to temperature. Also the diagram thats been suggested needs to have a non return valve added to teh cold water input line before the hot loop connects to it, otherwise as teh cold water warms its pressure will rise and you could push hot water back into the cold water pipework.

If youwere able to ditch the Trumatherm to release teh space would one of these help

 
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Hello Tom
I have just looked up the specs of the Deseo and Apparently you have a Truma VarioHeat which seems to be a more recent version of the their older E series heaters. This now makes more sense to have Trumatherm, but even so the Therm only holds 5L of hot water, but if that is at 65C, then when its mixed with cold water it should be enough for about 1 quick shower.

The Threm only has a 300W electric element, and that by its self will take about over an hour to heat up 5L from cold. It s difficult to know how effective the TrumaTherm is at recovering heat from hot air blowing through it Heat transfer from air to water is usually quite poor so whilst it will help - a bit it's not the best way of heating water.

I can see from the knaus catalogue there isn't much space available to to change things.

Just considering the second tank idea, if you are relying on the Trumatherm to heat it all, 300W is going to take a long time to get it all up to temperature. Also the diagram thats been suggested needs to have a non return valve added to teh cold water input line before the hot loop connects to it, otherwise as teh cold water warms its pressure will rise and you could push hot water back into the cold water pipework.

If youwere able to ditch the Trumatherm to release teh space would one of these help


Just read the specs as I was shocked by the 300 watt revelation. Seems it draws heat from the warm air heating! As you say, inefficient, but also useless in the summer.

In principle the extra tank idea may work, but you might only get 1 shower per week.

When I suggested it I did not realise the power output.

John
 
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I should add that the low wattage idea is clutching at straws as the power needed would blow any site ampage provision
I'm sorry but this statement doesn't seem to make sense. Low wattage devices only draw low currents, its high wattage devices that draw more current.

The Screwfix page I pointed out contains storage water heaters of 10 to 15L with a range of wattages . A 2kW element will draw typically about 8.7A. That should not blow most sites provisions in the UK.
 
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Just read the specs as I was shocked by the 300 watt revelation. Seems it draws heat from the warm air heating! As you say, inefficient, but also useless in the summer.

In principle the extra tank idea may work, but you might only get 1 shower per week.

When I suggested it I did not realise the power output.

John
Thanks for this response. Latest is that if I sacrifice the middle drawer on the kitchen unit, Truma and my dealer agree we can install a second truma unit alongside or above the first. This being legal and possible as there is no gas connection to worry about about in a kind of “floating “ configuration and external flue access not required. So I lose the possible benefit of gas for water heating but get my 10 litres of hot water. Note only the original unit will retain the dubious benefit of the heat exchange process as no room to route the ducting for the second unit. This seems to be the best compromise. It’s also much cheaper than the ultrastore which doesn’t fit anyway and the original heater can still be used so less waste. All in all I’ll settle for this Many thanks to all for their thoughts and advice
 
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JTQ

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If I understand this arrangement right, the addition of a very small circulating pump looping over the two would mean and heating provision now available in the original, would also be able to heat all the available water, the 10 kgs.
That benefits normal use in that the whole 10 kgs would also reach a common temperature.
 
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If I understand this arrangement right, the addition of a very small circulating pump looping over the two would mean and heating provision now available in the original, would also be able to heat all the available water, the 10 kgs.
That benefits normal use in that the whole 10 kgs would also reach a common temperature.

I would not have thought that was not necessary. Just pipe them in series and wire both heaters together, still only 600 watts, both tanks will be controlled by their own thermostats, so will still get the 10 litres from both,. The original one will also have the added benefit of air sourced heat when on. By drawing off the higher of the two tanks cold will feed into the bottom acting a bit like a domestic hot water immersion tank.

Sounds like a good solution in the circumstances.


John
 
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Hi all firstly an apology for confusing folks and not knowing my amps from my elbow!- well watts tbh. I was really losing the plot on this issue by the time I posted that “low wattage “ comment. So anyway I now have two thermes giving ten litres of water in total and all seems fine now.
I now have a new issue to solve- basically the skirt on the van prevents me getting my FIAMMA grey water tank under the outlets so I’m trying out various fixes including using an alternative tank with a lower profile. don’t want to cut into the skirt. If I get stuck I might ask you good folks for ideas and advice again. Many thanks
 
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JTQ

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I now have a new issue to solve- basically the skirt on the van prevents me getting my FIAMMA grey water tank under the outlets so I’m trying out various fixes including using an alternative tank with a lower profile. don’t want to cut into the skirt.

Run the van up onto suitable lift planks?
 
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Hi yes that’s in many respects the simplest option which I might well end up deploying if there isn’t an equally simple technical/routing solution. Guess I’m realising I’m more of an anorak than I thought 😂. Thanks
 

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