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  1. finchy01

    finchy01 Plumber GSR

    Went to a customers today, there boiler is coming on and heating a single radiator early in the morning and in the evening. My thoughts were does this have a pretty heat function? If so could be a dodgy divert or valve, she says it seems to be at the same time that the heating is due on though but as the room state is down it shouldn't come on, it's a digistat 3.

    I can't see its the frost stat as it even happened over the nice weather over the weekend.

    Can anyone advise if these do have a preheat function on them please and as always offer any other thoughts.

  2. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Rads not on the hot water circuit is it ?
  3. finchy01

    finchy01 Plumber GSR

    No. Combi boiler with all rads on heating.
  4. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

  5. Vee

    Vee Plumber GSR

    Yes. Can be diverter valve as the slave tank is likely to be reheated when hot water is being used more. On the right track.
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  6. Best

    Best Trusted Plumber

    I can only guess same.
    Is the rad that is getting heated the first on the circuit?
  7. finchy01

    finchy01 Plumber GSR

    Sounds like it (closest to boiler). They only notice it early mornings and evening when the heating is normally due to come on. I have said to check the rad 15 mi it's after drawing kids bath as if it is diverted valve the pre heat function should've kicked in then. Thanks for your input chaps.
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  8. magicno1

    magicno1 GSR

    Check valve letting by on the heating pump my friend!
    • Like Like x 1
  9. finchy01

    finchy01 Plumber GSR

    And the prize goes to magicno1 you were correct (although it was the nrv on both heating and hotwater and a failing dhw pump) full flush and parts replaced. All sorted now and my bank balence is looking a bit better too! Shame it was mates rates but it all helps. Thanks all for your replies.