In coming water temperatures

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Apr 23, 2024
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@charlesdobson I take your point about the higher pressure pumps , but with the flow at the tap reduced, the pressure in the boiler will be higher and reduce the kettling effect . A shower takes less water per second so the pressure in the boiler remains high .Your posts are slightly confusing/contradictory - just to clarify
. the water temperature is poor at the taps , but OK at the shower in the colder weather OR the shower also struggles ?.
If the former then it definitely flow rate that is limiting the temperature, if the latter then there may be a fault with the boiler controls .
What model of Imass do you have as on one it mentions water from an 'onboard tank' which would provide a supply of 'prewarmed' water which could be an option to fit inside your caravan
 
Nov 3, 2025
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@charlesdobson I take your point about the higher pressure pumps , but with the flow at the tap reduced, the pressure in the boiler will be higher and reduce the kettling effect . A shower takes less water per second so the pressure in the boiler remains high .Your posts are slightly confusing/contradictory - just to clarify
. the water temperature is poor at the taps , but OK at the shower in the colder weather OR the shower also struggles ?.
If the former then it definitely flow rate that is limiting the temperature, if the latter then there may be a fault with the boiler controls .
What model of Imass do you have as on one it mentions water from an 'onboard tank' which would provide a supply of 'prewarmed' water which could be an option to fit inside your caravan
The quicker you run water over the boiler the less time it has to heat it , I have tried various pumps with the boiler and found the lower litres per minute works better with it , remembering that most caravans run on a fairly small bore pipework to start with which can be a restriction in itself, so the higher psi pump isn’t a benefit, it just constantly cuts in and out
 
Mar 14, 2005
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I suspect you are expecting domestic hot water performance in a caravan, and sadly you simply do not have the same equipment to be able to deliver that type of performance.

You have indirectly indicated you have an Imass system, but you have not told us which make and model of caravan you have.

As Roger has pointed out the Imass information on line states the heater can only raise 3.3 litres of water per minute by 37.7C. You must be using more water than 3.3l/m if your unable to get 40C water.
 
Last edited:
Nov 3, 2025
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I suspect you are expecting domestic hot water performance in a caravan, and sadly you simply do not have the same equipment to be able to deliver that type of performance.

You have indirectly indicated you have an Imass system, but you have not told us which make and model of caravan you have.

As Roger has pointed out the Imass information on line states the heater can only raise 3.3 litres of water per minute by 37.7C. You must be using more water than 3.3l/m if your unable to get 40C water.
Well hopefully I’m going to cure this problem, the heater had no problem during the summer going to 45/50C , I’m going to replumb the caravan so that water for the heater flows through the onboard tank with a heat mat underneath to pre warm the water , hopefully this cures the problem!
 
Nov 3, 2025
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Are heat mats available between 4 and 6kw and does the heat go directly into the water without dispersing else where?
It’s a heat mat which you attach to the bottom of the tank , was a ****** of job getting the on board tank in the caravan out and rerouting the cold water away from it , but hopefully once all the bits arrive it should be source of warm water for the heater if it works 🤞
 
Nov 3, 2025
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It’s a heat mat which you attach to the bottom of the tank , was a ****** of job getting the on board tank in the caravan out and rerouting the cold water away from it , but hopefully once all the bits arrive it should be source of warm water for the heater if it works 🤞
Are heat mats available between 4 and 6kw and does the heat go directly into the water without dispersing else where?
Sorry the heat mat I ordered is a 6kw unit , but all depends where your using it I suppose, technically I think you buy an immersion style heater like you have at home , not sure if a plastic tank could withstand that, and would the water be too warm then??
 

Sam Vimes

Moderator
Sep 7, 2020
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If at any point you are storing hot water, as opposed to just using instantaneous heating, then you need to ensure that, that hot water is periodically taken to a temperature above 60degC to avoid bacterial growth such as Legionella.
 

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