Can’t turn heating off

Discussion in 'Plumbing and Central Heating' started by Ian Gregson, 15 Nov 2021.

  1. Ian Gregson

    Ian Gregson

    Joined:
    15 Nov 2021
    Messages:
    4
    Thanks Received:
    0
    Country:
    United Kingdom
    Hi all,
    I’ve a problem with my heating. It’s a S-Plan with 2 Honeywell motorised valves. All was good till last week. Hot water runs fine and goes off when programmer tells it too. Heating will not go off even when programmer isn’t asking it to. I’ve replaced heating motorised valve and changed the programmer (Honeywell st9400c) but still the problem persists. Only way to stop heating is to knock fuse spur off then it does stay off. Any ideas Thanks
     
  2. Sponsored Links
  3. picasso

    picasso

    Joined:
    8 Apr 2008
    Messages:
    10,688
    Thanks Received:
    2,687
    Location:
    Essex
    Country:
    United Kingdom
    Either a wiring mistake or you have changed the wrong valve.
     
  4. Ian Gregson

    Ian Gregson

    Joined:
    15 Nov 2021
    Messages:
    4
    Thanks Received:
    0
    Country:
    United Kingdom
    Thanks for the reply. It’s been working fine for 10 years. Wired into a Honeywell wiring centre. So it’s wired as it’s always been.
     
  5. Exedon

    Exedon

    Joined:
    2 Oct 2021
    Messages:
    290
    Thanks Received:
    101
    Location:
    North Notts/South Yorkshire
    Country:
    United Kingdom
    Multimeter and find where permanent live is coming from
    Maybe a clear picture of your wiring center?
     
  6. Ian Gregson

    Ian Gregson

    Joined:
    15 Nov 2021
    Messages:
    4
    Thanks Received:
    0
    Country:
    United Kingdom
  7. FiremanT

    FiremanT

    Joined:
    16 Jan 2012
    Messages:
    9,803
    Thanks Received:
    1,991
    Location:
    Uk
    Country:
    United Kingdom
    Have you a Frost Thermostat (in the loft, maybe?)

    Some boilers have a built in Frost stat, what model have you?
     
  8. Ian Gregson

    Ian Gregson

    Joined:
    15 Nov 2021
    Messages:
    4
    Thanks Received:
    0
    Country:
    United Kingdom
    Hi, it’s an oil fired firebird. No frost stat.
     
  9. Sponsored Links
Loading...

Share This Page