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Discuss Cold water tank in the attic overflowing in the Central Heating Forum area at UKPlumbersForums.co.uk.

  1. GGg

    GGg Member

    Hi All,

    Looking for some advice. The tank in the attic has been trickling out of the overflow for a few weeks now.

    I have an open vented system with a hot water pump (Stuart Turner monsoon twin 3) fitted.

    Have already changed the valve and float in the attic. Set it very low but water is above the float. Tested it fine know it shuts off the feed that way.

    Also changed the thermostat on hot water cylinder, so tank isn’t getting too hot and venting over.

    I do have a shower fitted with mains cold and tank fed hot. (Plumber at the time said it would be fine because hot water is pumped) as well as 3 other mixers in the house with same hot/cold set up.

    Looking online could it be the hot water is being overpowered by the cold, with mains then backfilling down the hot water pipe and filling the attic? I can see this can be resolved with a non return valve? And instead of fitting 4 non return valves can I fit one 22mm NRV on the flow from the pump? (Not the feed as this stops any ability to vent)

    Thanks and sorry for the long winded post.
     
    • Like Like x 1
  2. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Positive head or neg head pump ?
     
  3. GGg

    GGg Member

    Positive Head.
     
  4. CBW1982

    CBW1982 GSR Top Contributor!!

    It can be yes, a customer had a tap fitted and another plumber had changed the float valve twice. Turned out it was backfilling the cwsc (cold tank) and overflowing. I advised he fit check valves or change the tap.
     
  5. CBW1982

    CBW1982 GSR Top Contributor!!

    If you want to check this then try and put your hand in the tank and feel where the cold feeds the cylinder
     
  6. GGg

    GGg Member

    Ok thanks for the responses. Will try the feed later, if it is this, will one check valve suffice (on the outlet on the pump) or will I need one installed at each mixer?
     
  7. Riley

    Riley S. Mod Trusted Plumber GSR Top Contributor!!

    Split coil in cylinder or faulty mixer
     
    • Agree Agree x 2
  8. Riley

    Riley S. Mod Trusted Plumber GSR Top Contributor!!

    does the pump do all hot in the house
     
  9. GGg

    GGg Member

    Yes feeds the whole house.
     
  10. Riley

    Riley S. Mod Trusted Plumber GSR Top Contributor!!

    Then just at the pump should suffice
     
    • Like Like x 1
  11. GGg

    GGg Member

    Mixers are brand new, how would I test a split coil? Wouldn’t the heating tank be draining?
     
  12. Riley

    Riley S. Mod Trusted Plumber GSR Top Contributor!!

    Is your smaller f&e tank above or below the larger cold water tank
     
  13. GGg

    GGg Member

    Below I think? The plumber bloke tested the “levels” in the tanks and they were fine?
     
  14. Riley

    Riley S. Mod Trusted Plumber GSR Top Contributor!!

    If the level of the f&e is above the cwsc then if the coil is split the two will try and level out.
     
  15. GGg

    GGg Member

    Ok thanks. Any easy way for me to check the coil?
     
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