Room Thermostat not turning off central heating.

Discussion in 'Plumbing and Central Heating' started by lavenderman, 19 Jun 2010.

  1. lavenderman

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    I hope someone here will be kind enough to help me. I have for the past few days been having the central heating come ON, on its own despite the Room thermostatic control downstairs and the central heating timer control attached to the Boilermate 2000 button being in the OFF/0 position.

    I have turned off the valve controls to all the radiators in all the rooms bar the one in the hallway that does not have radiator valve control,yet the central heating comes on blazing hot on its own and then turns itself off without it being switched on by anyone, and not time-controlled.

    This is driving me crazy and hope that someone here will be able to help, more so now that summer is here.

    I have the following for hot water and central heating: Boilermate 2000, Gloworm Micron boiler and Siemens RAA02.1N Landis & Staefa room thermostat control.

    What could be wrong? I have just ordered a replacement Siemens RAA02.1N Landis & Staefa Room Thermostat control in the hope that this will fix the problem. Any advice/solution will be most welcome and appreciated.

    Lavenderman.
     
  2. picasso

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    It sounds more like the control board has failed on your boilermate 2000, it wont be the stat if the control is switched off.
     
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  3. Tipper

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    More likely to be the motorised valve has failed.

    The valve head contains aux switches that control the boiler and pump so failure of these means the heating gets stuck on or is slow to resond.

    Change the motor head.
     
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  4. JMLanders

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    Think I'd be inclined to disconnect any external controls to determine where the fault actually lies.
     
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  5. 45yearsagasman

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    Nice idea except the boiler mate 2000 is a thermal store and does not incorporate a motorised valve!...More likely to be external controls.The ch pump is operated by the timer on the boilermate in conjunction with a room stat.Prove these controls are switching correctly before fitting expensive pcb's.The pump will start for a few secs avery few days to prevent ch pump sticking in the Summer.It also provides pump overrun.You should call a qualified engineer to diagnose fault.Guesses can prove expensive.
     
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  6. lavenderman

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    Thanks a lot gentlemen for all your contributions and wise advice, from Picasso, Tipper,JMlanders to 45yearsagasman.


    To 45yearsagasman, your well spoken advice is taken on-board.

    Will certainly check with a qualified engineer on diagnosis and way forward. Thanks to everyone.

    Lavenderman.
    --------------------------------------------------------------------------------

     
  7. GrahameS

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    May I revive this thread and ask about a similar scenario:
    Our system is less than 2 yrs old.
    Oil boiler and pumped system with three circuits - two-zoneUFH/rads/DHW - each with two-way Honeywell MVs

    After the programmer reaches its "OFF" time, the room stat still shows red light and the manifold valves for each loop in the zone are open ie flowing hot water.
    If I turn the stat down it clicks and the light goes off. If I turn the stat up the light stays off and the hot flow stops.
    I got the electrician who did the original work to have a look. He did some testing with a meter in the controller and fiddled with the lever on the MV. He thought it was fixed but it's just the same.
    Is it the micro-switch in the MV?
    And is it easy to swap the powerhead myself?
     
  8. GavThePlumber

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    :LOL:
     
  9. GrahameS

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    Thanks for that.
    I did wonder because the system/ symptoms are not the same.
    I don't want to replace bits unnecessarily
    And ... is it easy DIY job?
    I see direct replacements advertised with same wire colours etc
     
  10. Blagard

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    Changing the head of a motorised valve is easy (if it is accessible!) Colour codes are the same so wire up like for like.

    The Honeywell has a couple of screws to secure the head. accessed from the valve body side. Just undo and lift off There are two locating pegs in the other corners so don't try to undo them! Take tension off the drive shaft by moving the head lever into the manual venting position first

    If no screws there you may have an older one without replaceable head
     

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