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Is the position of the thermometer too high on the hot water cylinder?

Discussion in 'Plumbing and Central Heating' started by groovybug, 25 Sep 2021.

  1. groovybug

    groovybug

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    Hello everyone,

    We have just moved in our new place and notice the hot water does not keep the temperature for very long. One reason is that the hot water pipe have to go up to the loft before going back down to the bathroom, so it loses quite a lot of heat that way. Another possible reason I notice is that the thermometer is quite high up on the cylinder. Please see photo. Are they normally this high? As I imagine when the boiler would be cut off before the water at the bottom is warm enough.

    Should I attempt to cut out the foam at the bottom and move the thermometer there? If there's any potential pitfall please let me know.

    Many thanks!
     

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  3. ianmcd

    ianmcd

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    Yes you are correct, the thermostat is far too high
     
  4. groovybug

    groovybug

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    @ianmcd Thank you. What is the correct position? And is it a simple job of cutting out the foam and move it down, or is there anything I should be aware of?
     
  5. ianmcd

    ianmcd

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    About 300mm from the bottom of the cylinder, cut the lagging the same size as the origional cut, move the stat to the new position, use the bit you have cut out to plug the old cut out, set it at 60 and you are good to go, best if you turn the HW off when you are doing it , but not really a big problem, very easy job, you will get a massive boost in your HW times when you do this , but obviously your energy bills will increase
     
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  6. ianmcd

    ianmcd

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    your HW will feel a lot hotter when you do this as the top of the cylinder will now be hotter than 60 Degrees, dont turn the stat down any lower than 55 degrees this is to protect you from legionaella forming in the stored HW, the reason the top will get hotter is called stratification, google it and you will see what I mean
     
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  8. oldbuffer

    oldbuffer

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    1. The normal position for a cylinder thermostat is 1/3 of the way up the cylinder.
    2. If the system has a secondary circulation pump, this acts to an extent as a destratification pump, which means there will be little temperature gradient in the water in the cylinder. In these circumstances it doesn't matter much where the thermostat is as all water is at more or less the same temperature.
     
  9. ianmcd

    ianmcd

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    I know that you mean well, but if you actually look at the pic, your post offers nothing in his situation, you are totally correct in a situation that this applies , but you are just confusing the post
     
  10. groovybug

    groovybug

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    @ianmcd Did it! Thanks for your help. I understand it now. It explains why I needed to turn up the thermostat up to 75 degree before to get enough hot water.

    @oldbuffer This system does not have a secondary circulation pump I suppose?
     
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  11. ianmcd

    ianmcd

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    You dont have a secondary circulation system leave the HW on for a few hours then come back and post how good your bath was :love:
     
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