Off grid hot shower water ideas - RE< Heated aqua roll thread

Jun 23, 2020
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After in the research to other topics i found this thread. Now before it went off on its rantings about Chinese quality and products it had quite a good range of ideas. I did like the maths as its better to show a working theory.

I did think it had a massive own goal with heating water and showers with low wattage equipment. Was to pre heat the water as much as possible!

Say we are off grid and we have a small or low power heating system, either gas or electric. Its irrelivent which for this idea.

Our ideal shower temp is say 40 degrees C. (thats a guide not a requirement)

If our standard aqua roll cold water is ambient say 10 degrees, we need to heat from 10C to 40C. Clever people can workout that 20 litres plus 30C temp change is so many BTU and therefore so many Watts. Fairly simple basic stuff. But why does the water have to start at 10C. There is no reason why that is.

But why has no one mentioned to simply paint the aqua roll matt black and stand it on a piece of insulation. You could further improve on that with a simple clear plastic green house type box to better pre heat the water and contain collect the solar therms.

If the water temp starts at say 15C or even 20C then its a lot less watts/BTU's to get to the same heated shower temp. Less power input but the same result.
 
Mar 14, 2005
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After in the research to other topics i found this thread. Now before it went off on its rantings about Chinese quality and products it had quite a good range of ideas. I did like the maths as its better to show a working theory.

I did think it had a massive own goal with heating water and showers with low wattage equipment. Was to pre heat the water as much as possible!

Say we are off grid and we have a small or low power heating system, either gas or electric. Its irrelivent which for this idea.

Our ideal shower temp is say 40 degrees C. (thats a guide not a requirement)

If our standard aqua roll cold water is ambient say 10 degrees, we need to heat from 10C to 40C. Clever people can workout that 20 litres plus 30C temp change is so many BTU and therefore so many Watts. Fairly simple basic stuff. But why does the water have to start at 10C. There is no reason why that is.

But why has no one mentioned to simply paint the aqua roll matt black and stand it on a piece of insulation. You could further improve on that with a simple clear plastic green house type box to better pre heat the water and contain collect the solar therms.

If the water temp starts at say 15C or even 20C then its a lot less watts/BTU's to get to the same heated shower temp. Less power input but the same result.
On the basis that normally the standard water heater will raise the temperature of the water in its tank to between 65 and 70C, which is far too hot to shower with, so you mix in some cold at the shower mixer to bring it down to a comfort level. By doing this the 10Lof very hot water in your heater is diluted and can become nearer 20 litres for showering.

Certainly In theory your suggestion does work, and raising the temperature of the cooler water will further extend the quantity of comfortable water available at the shower.

The question is how to heat the barrel. You are suggesting solar as a possible solution. My own sister has some of her hot water heated by a solar collector and that is in the UK , but the gear she needs to make it work is large and and has some weight to it. Not ideally suited to a caravan.

You suggest using the barrel as its own collector by painting it black and placing it under a cloche to keep warmed air close to it. This has some merit, except painting it black would also maximise its radiation of heat from side facing away from the sun. Also you need to ensure it was able to receive the sun which isn't always possible depending on the site, and of course the as teh day passes the angle to sun may cause shadows to move across the barrel -

This is all becoming a lot of work to have a shower.

It would surely be simplest to have an insulated barrel with a submersible fish tank heater set to 20 or 25C running over night so you have a nice warm barrel ready for the morning shower.
 
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These are very effective in summer. If you could create your own using the same material you may be onto a winner on sunny days whenever they happen.
 
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Mar 29, 2021
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Diesel heater plugs????
Thought about hot water when we used to tent.

I have seen YouTube videos of folk heating hot tub water by putting a central heating radiator in basically a fire and letting the principal of heat rises to circulate the plumbed water
 
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There seems to be a never ending discussion on how to use the shower, my caravan shower is great, I put the heating on boost and I have a full hot water tank so I get in the shower, I’m in there for 5 minutes and I’m clean from top to toe, I come out of the shower and within a short time with the water heater on boost there is another full tank of hot water for my better half to have her shower and 5 minutes later she’s showered from top to toe, this isn’t difficult at all, why on earth anyone needs more than 5 minutes in a hot shower is beyond me unless people are OCD or maybe coalminers might have needed a bit longer, while on a caravan site I can’t think of any activity that could possibly render me so dirty I’d need to shower for more than 5 minutes.

BP
 
Jun 23, 2020
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Diesel heater plugs????
Thought about hot water when we used to tent.

I have seen YouTube videos of folk heating hot tub water by putting a central heating radiator in basically a fire and letting the principal of heat rises to circulate the plumbed water

theres several well tried options i could use and discuss here. The one i use in my old caravan was a copper stove top coil design. but with the likes of professor john's ilk here best i don't! Think its time to revert back to read only forum member.
 
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theres several well tried options i could use and discuss here. The one i use in my old caravan was a copper stove top coil design. but with the likes of professor john's ilk here best i don't! Think its time to revert back to read only forum member.
We was watching a similar device t'other night on telly, but it didn't have water coming out, Gin!😄
 
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There seems to be a never ending discussion on how to use the shower, my caravan shower is great, I put the heating on boost and I have a full hot water tank so I get in the shower, I’m in there for 5 minutes and I’m clean from top to toe, I come out of the shower and within a short time with the water heater on boost there is another full tank of hot water for my better half to have her shower and 5 minutes later she’s showered from top to toe, this isn’t difficult at all, why on earth anyone needs more than 5 minutes in a hot shower is beyond me unless people are OCD or maybe coalminers might have needed a bit longer, while on a caravan site I can’t think of any activity that could possibly render me so dirty I’d need to shower for more than 5 minutes.

BP

Fully agree, nearly what we do but don’t bother with the boost. Just give it 10 mins and all is fine. As we shower 1st thing, I alway make sure that the aquaroll is full the previous night, we get two showers and the breakfast dishes from that.

I think the technique is called ‘submarine showering’.

John
 

Sam Vimes

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What ever method you choose to heat or pre-heat to provide hot water its important to realise that the system should ideally be above 60degC to prevent the buid up of Legionella Bacteria. These bacteria thrive at temperatures between 20-45degC. They lay dormant below 20degC

FWIW: I have solar hot water system on my house. The panel is about 2.5sqm and on a good day -like yesterday and that's on the west coast of Scotland - it will take the hot water tank to 55 - 65degC. Periodically I will boost it with the immersion heater to get to the 60degC critical temperature.
 

JTQ

May 7, 2005
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A trouble with heating the Aquaroll is then there is no cold water supply in the caravan, we use water other than hot.
As said it also brings accelerated biological activities, far more than just the mentioned Legionella Bacteria.
 
Jul 18, 2017
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Fully agree, nearly what we do but don’t bother with the boost. Just give it 10 mins and all is fine. As we shower 1st thing, I alway make sure that the aquaroll is full the previous night, we get two showers and the breakfast dishes from that.

I think the technique is called ‘submarine showering’.

John
On a submarine you just step outside for a wash. LOL! :D
 
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Nov 11, 2009
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Fully agree, nearly what we do but don’t bother with the boost. Just give it 10 mins and all is fine. As we shower 1st thing, I alway make sure that the aquaroll is full the previous night, we get two showers and the breakfast dishes from that.

I think the technique is called ‘submarine showering’.

John
Yes it is, but not every day, unless there's a reactor on board.
 

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