Hot Water Tank Thermostat

Discussion in 'Plumbers' Talk' started by SoulConspiracy, Aug 31, 2017.

  1. Devil's Advocate

    Devil's Advocate Well-Known Member

    I don't think that metal strip is actually meant to make contact with the cylinder wall - I think it's the bi-metallic strip which needs to move to operate?

    Anyhoo, I think there should be a light 'click' as you rotate the dial.

    In any event, if your programmer is set to DHW, turning the 'stat down and up slowly should operate the boiler. The 3-port valve might not actually move if only the DHW is on - I think it defaults to that position? So to test this properly, turn on the CH as well - that should get the 3-port valve in to the centre position, and turning the cylinder 'stat DOWN should then see it move to the CH direction.

    Anyhoo, you can buy new 'stats for a £enner on t'Bay.
  2. Yeah, having the tinfoil making the contact between the sensor and the tank has just shorted the thermostat altogether so the hot water didn't come on at all (cold shower for me).

    I rotated the dial some times and heard a light click every now and then but never at the same point and not everytime. I found it impossible to tell if it was a switch clicking or just something randomly making a little noise.

    I'll run through that test with the central heating on this evening.
  3. Replaced the thermostat. Problem is definitely fixed now. Thanks for your help guys.
    Devil's Advocate likes this.
  4. Devil's Advocate

    Devil's Advocate Well-Known Member

  5. I have a new issue now!

    Now that I've turned the heating on, it's overriding the temperature that I've set on the tank thermostat, the water is piping hot again!

    I suspect this is about how it's wired up and will probably need a heating engineer in.
  6. Dr Bodgit

    Dr Bodgit Well-Known Member

    Yes sounds like it, the tank thermostat should be in series to the boiler on the HW side.
  7. Devil's Advocate

    Devil's Advocate Well-Known Member

    Could be, Soul. Or perhaps the 3-port valve is letting by on the DHW side.

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