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Housing - Renovation: Insulating toliet cisterns- cold radiator effect

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  1.  
    • CommentAuthorwholaa
    • CommentTimeMar 26th 2023
     
    Hi all,
    I was inspired by comments on this forum that toilet cisterns can chill bathrooms unnecessarily. I looked into the topic and found high-end toilets tend to be insulated, for example, Toto Japanese toilets (EPS). So I have been experimenting with this and trying to find the best way. I tried squirty foam, but it is very messy and bulky. It can be trimmed, but water enters many bubbles and may compromise the insulation properties. Anyway, when I did half of a cistern with squirty foam, I could see the side of the toilet cistern with squirty foam was a solid 2-3°C warmer than the non-treated parts. Has anyone else tried other methods? EPS glued on PVA glue?
  2.  
    The (plastic) toilet cisterns you get over here are all lined with about 3mm of EPS which stops condensation forming on the outside of the cistern - and by the same effect keeps the sides warmer. Are you talking about additional insulation to this 3mm or is your cistern without the built-in EPS?
    • CommentAuthortony
    • CommentTimeMar 26th 2023
     
    Insulation will slow the passage of heat, nor eliminate it. The overall picture will be the same with or without insulation in the long term. Keeping the cistern empty would work but not really practical.
    • CommentAuthorwholaa
    • CommentTimeMar 26th 2023 edited
     
    Posted By: Peter_in_HungaryThe (plastic) toilet cisterns you get over here are all lined with about 3mm of EPS which stops condensation forming on the outside of the cistern - and by the same effect keeps the sides warmer. Are you talking about additional insulation to this 3mm or is your cistern without the built-in EPS?


    Where I live all or nearly domestic toilets have no insulation or plastic bucket inside. Just bare ceramic. I suspect that the expensive concealed toilets in new business are but I cant be sure.
    • CommentAuthorrevor
    • CommentTimeMar 26th 2023
     
    The recent plastic cistern I have installed had an EPS moulded sleeve around it precisely to avoid condensation. I recall an ex neighbour having a bit of a disaster with a ceramic cistern after flushing the toilet the inrush of cold fill caused the ceramic to "disintegrate" presumably a fault and and change in temperature. A good argument for have cisterns fill from storage tank rather than mains.
    • CommentAuthorwholaa
    • CommentTimeMar 26th 2023 edited
     
    Posted By: tonyInsulation will slow the passage of heat, nor eliminate it. The overall picture will be the same with or without insulation in the long term. Keeping the cistern empty would work but not really practical.


    True but in a busy household, a toilet might be used a lot, if you have a house full of kids, it might be every 10 mins even. So maybe there isn't time for the cistern water to equalize to room temperature. Also many toilets have leaks and the water never stops refilling. To be fair, new toilets have small volumes but the old ones can really be enormous volumes of water.
  7.  
    If it is an old high volume ceramic cistern and given the amount of effort (and cost of squirty foam) needed to insulate the existing perhaps a new insulated plastic cistern is justified.
    • CommentAuthorCliff Pope
    • CommentTimeMar 27th 2023
     
    We've a cast iron overhead cistern in the downstairs bathroom, and it often drips condensation on the user.
    I have sometimes idly wondered if connecting it to the nearby hot pipe to the bath instead of the cold would work.
    It wouldn't always get very hot because depending on use it can take quite a long time before significant hot water arrives down the long pipe run from the tank, but it would at least be lukewarm.
    And when it was hot the cistern would become a radiator.
    •  
      CommentAuthordjh
    • CommentTimeMar 27th 2023
     
    Posted By: Cliff PopeI have sometimes idly wondered if connecting it to the nearby hot pipe to the bath instead of the cold would work.
    Love the idea, although it sounds expensive in running costs. Surely better and probably cheaper to just replace the cistern with a modern insulated one?
  10.  
    Posted By: wholaa
    Posted By: tonyInsulation will slow the passage of heat, nor eliminate it. The overall picture will be the same with or without insulation in the long term. Keeping the cistern empty would work but not really practical.


    Also many toilets have leaks and the water never stops refilling. To be fair, new toilets have small volumes but the old ones can really be enormous volumes of water.


    If your toilet is free flowing, get it fixed - my mothers toilets started doing that and no-one told me... resulting in a £1500 water bill (I appealed due to her dementia and was let off).

    If your toilet has a very large volume, reduce it by adding a brick or other object to reduce the volume.

    The geberit 'in wall' cisterns I've fitted aren't insulated

    Posted By: Cliff Popeays get very hot because depending on use it can take quite a long time before significant hot water arrives down the long pipe run from the tank

    So most of the hot water you run would be wasted in the 'dead leg' of the pipe.
  11.  
    You can get self adhesive neoprene foam sheets that could be stuck on the inside of the cistern.

    The idea is to hold a thin layer of water that is already at room temperature against the cistern wall. It won't stop the water in the rest of the cistern absorbing heat from the room, like Tony said, just to stop the inflow of cold water being in direct contact with the cistern wall.
    •  
      CommentAuthordjh
    • CommentTimeMar 28th 2023
     
    Worth noting that push-button valves are notorious for leaking. Lever types much less so. We've got dual-flush Dudley ones. I believe they do insulated ones.
    • CommentAuthorDavidND
    • CommentTimeApr 21st 2023
     
    <blockquote><cite>Posted By: djh</cite>Worth noting that push-button valves are notorious for leaking. Lever types much less so. We've got dual-flush Dudley ones. I believe they do insulated ones.</blockquote>

    Like all things mechanical, ALL dump valve toilets need regular maintenance. As they do not operate using the syphonic effect they are overall much more efficient, however, that also depends on the WC pan too.

    I teach ALL of my customers how to 'see' issues before they become expensive. FYI, that 'advice' is to catch the light in the surface of the bowl water. If it is not PERFECTLY still then get it sorted. Obvs this needs to be done regularly and leaving 5 mins after using the toilet.

    In terms of condensation, the amount of it depends entirely on the diff tween internal & incoming water temp. Manufacturers insulate cisterns to 'reduce' that overall 'shock' exposure which allows the incoming water to slowly rise to ambient temp. In the past I have successfully reduced condensation by using self adhesive nitrile panels (12mm) put on the OUTSIDE of the cistern. Reducing the area it can condense on reduces the qty of condensate.
    •  
      CommentAuthordjh
    • CommentTimeApr 21st 2023
     
    Posted By: DavidNDLike all things mechanical, ALL dump valve toilets need regular maintenance. As they do not operate using the syphonic effect they are overall much more efficient, however, that also depends on the WC pan too.
    Yes, sorry, it is of course the valve rather than the means of operation that matters. The Dudleys have a lever-operated siphonic valve. Push-button WCs tend to have dump/drop valves that are notoriously leaky.

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