In coming water temperatures

Nov 3, 2025
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As we come into the colder part of the year, I find my instantaneous water heater struggles with the incoming water temperature, its designed to work with a 15 degree incoming temperature, I use a 40 L aquaroll with a float from the mains hook up to keep it constantly filled, have the barrel rised off the ground to stop the cold getting into the barrel, but with the water coming in at 8/9 degrees it’s hard , someone suggested putting a heater in the barrel, like you see in a fish tank , any other suggestions would be most welcome
 
Nov 6, 2005
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As we come into the colder part of the year, I find my instantaneous water heater struggles with the incoming water temperature, its designed to work with a 15 degree incoming temperature, I use a 40 L aquaroll with a float from the mains hook up to keep it constantly filled, have the barrel rised off the ground to stop the cold getting into the barrel, but with the water coming in at 8/9 degrees it’s hard , someone suggested putting a heater in the barrel, like you see in a fish tank , any other suggestions would be most welcome
I wonder if the instantaneous water heater is simply not designed for UK temperatures as the average UK temperature, over a full year, is only about 10 degrees C which will be the average water temperature coming in.

Putting a heater in the barrel would be very inefficient, wasting most of it's energy to the atmosphere.

You could fit a supplementary water heater between the cold intake and the instantaneous heater.
 
Nov 3, 2025
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Had thought of that , but it’s very hard to get a heater that will only bring the water temperature up to 15 degrees or there abouts ??
 
Mar 14, 2005
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Hi and welcome to the forum.

One of the forums members has already gone through a similar exercise, unfortunately I can't remember who it was, but I suspect he had a differnt heater in the caravan as he was looking to raise the external tank above 15C.

When posting technical questions it can help us a lot if you can provide make model and year of caravan, and similar information about any specific appliances your query may be about.

I suspect a fish tank heater and thermostat may be all you need. It would be best to have an adjustable thermostat. If you were to insulate your water barrel it would improve the efficiency, and of course would help prevent freezing.
 
Nov 11, 2009
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Hi and welcome to the forum.

One of the forums members has already gone through a similar exercise, unfortunately I can't remember who it was, but I suspect he had a differnt heater in the caravan as he was looking to raise the external tank above 15C.

When posting technical questions it can help us a lot if you can provide make model and year of caravan, and similar information about any specific appliances your query may be about.

I suspect a fish tank heater and thermostat may be all you need. It would be best to have an adjustable thermostat. If you were to insulate your water barrel it would improve the efficiency, and of course would help prevent freezing.
It was Grey13 who put a lot of time into producing a system with additional heating so that he could enjoy longer showers. Last post was around time he was heading to italy with a new Jaguar F Pace tow car.

A search of his posts will highlight what he did. Look at “heater” by Grey13 and there are two detailed threads come up.
 
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Nov 6, 2005
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Remember that increasing the barrel water temperature will increase the temperature of water from the cold taps.
 
Nov 3, 2025
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Remember that increasing the barrel water temperature will increase the temperature of water from the cold taps.
I think a previous suggestion of fitting an inline heater between the supply to my heater and the cold sounds like a good idea, would be easier to regulate, but it’s finding such an item is the trick!
 
Sep 23, 2023
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In line water heaters are available from aquarium stockists and are used on tropical fish tanks etc,as are various heaters that incorporate a thermostat usually Upto 500 watts (approx upto 32°)
 
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Nov 3, 2025
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In line water heaters are available from aquarium stockists and are used on tropical fish tanks etc,as are various heaters that incorporate a thermostat usually Upto 500 watts (approx upto 32°)
Yes but they are designed to heat a fixed tank , not one that is constantly being topped up with cold water, from research it would take a 4kw to 6kw inline water heater to bring a constantly flowing tank from 10 degrees to 15 degrees, and couldn’t see many site hook ups withstand that amount of electricity
 
Nov 3, 2025
7
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10
Hi and welcome to the forum.

One of the forums members has already gone through a similar exercise, unfortunately I can't remember who it was, but I suspect he had a differnt heater in the caravan as he was looking to raise the external tank above 15C.

When posting technical questions it can help us a lot if you can provide make model and year of caravan, and similar information about any specific appliances your query may be about.

I suspect a fish tank heater and thermostat may be all you need. It would be best to have an adjustable thermostat. If you were to insulate your water barrel it would improve the efficiency, and of course would help prevent freezing.
Thank you ,
To be honest this has only been a problem developed last week, and maybe it’s a sign to wrap up for the year , the caravan itself is getting cold at night , and we have had a good run this year despite all the storms. Caravan is home and will start clearing it out for the winter and get the cover on , and let it be a problem for next year when the season starts again
 
Nov 16, 2015
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In the winter we would normally run the water heater on gas and electric at the same time, kept the caravan at 15c during the night.
Oh and padded covers on the aqua rolls.
 
Apr 23, 2024
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The air pressure fault is a sign the water is boiling , producing small pockets of steam causing the boiler pressure to jump up ( this effect is known as kettling and is a sign of low water pressure within the boiler) , if this is the case you may be be losing temperature in the pipes from the boiler to the taps , insulating them may help with a greater flow. An instantaneous water heater is designed to work with incoming water pressure of about 2 bar, external water pumps struggle to achieve when water is flowing. Fitting an internal pump would give greater pressure whilst water is flowing and not cause the water heater to struggle or kettle .
 

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