Half hot radiator.

Discussion in 'OT (OFF Topic) Forums' started by Tan, Jan 21, 2011.

  1. Tan

    Tan Hardcore MB Enthusiast

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    Hi

    We have yet another problem with the heating system, the boiler is still working which is a start, but the first radiator that normally warms up has only become half warm. The left side where the TRV is is getting hot but the right side is cold and the rest of the radiators are cold.

    Any ideas what this may be, could it be sludge build up, previously I have heard that with sludge build up, it's normally cold bottom warm top and when its trapped air, its is normally the reverse and thus needs bleeding.

    Could this be a pump or low system pressure?

    Many thanks

    Tan
     
  2. renault12ts

    renault12ts MB Club Veteran

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    Tan, you say the rest of the radiators are cold, or do you mean the rest of this rad is cold?
     
  3. Pontoneer

    Pontoneer MB Club Veteran

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    You should be able to determine water flow if you open bleed valves and water spurts out ?

    Are the individual valves on the radiators perhaps turned off ?

    Sorry , I don't know enough to suggest any more .
     
  4. OP
    OP
    Tan

    Tan Hardcore MB Enthusiast

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    I am not at the house yet, but it's described as rest of the rads are cold as is half the first rad.
     
  5. jkeith

    jkeith Active Member

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    Sounds like your pump is not working. If you have a conventional gravity fed system, the best way to determine if your pump is working is to use a screwdriver as a stethescope on the pump body.

    Half hot radiators on the first floor of a two storey house is often a ball valve stuck in the closed position and evaporation causing the upper system level to reduce.

    Make sure the programmer is asking the pump to run.

    If the pump is running, you either have a system blockage caused by an air lock (especially if a system has been filled from the top instead of the lowest point) or a very badly sludged up system (which would have been evident over a period of time of poor circulation).

    Hope this helps
     
  6. OP
    OP
    Tan

    Tan Hardcore MB Enthusiast

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    Seam as though the pump works but the pressure in the system is fluctuating, causing the boiler to switch on and off. What would cause this?
     
  7. jkeith

    jkeith Active Member

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    If it is a pressurised system, the diaphragm could have failed.

    If it is a gravity fed system, there is air blocking flow.

    It sounds from what you say (the pressure in the system is fluctuating) that it is a pressurised system. Try switching the system off and venting all the rads starting with the lowest (gr flr?).

    Difficult to give a more precise diagnosis without any knowledge of what type of system you have (mini-bore, micro-bore, gravity) and what recent work has been done that may lead to the symptoms.
     
  8. StevenN

    StevenN Hardcore MB Enthusiast

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    Hi Tan

    Sorry to hear you are still having trouble.

    It could even be a blocked return filter.

    I think it's time to get the plumber back in.


    Steve
     
  9. OP
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    Tan

    Tan Hardcore MB Enthusiast

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    Thanks all, looks like one radiator valve is leaking, have closed it and the system is working again, will get a plumber in over the weekend. Annoyingly the plumber that did the install has gone awol.
     
  10. jonnyboy

    jonnyboy Hardcore MB Enthusiast

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    I have to say Tan, from the previous posts about your intall, I think in the long run this is quite a result actually !! I think you are better off without him IMHO
     
  11. Rich27

    Rich27 Active Member

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    Sounds like its sludged up to me.

    When we moved in we had a couple of radiators with the same syptoms, its an easy cure.

    Turn off the valves at either side and undo the large connector nut from radiator to the pipes you can Drain the radiator with a washing up bowl undernearth one of the connector nuts if it doesnt have a drain valve.
    Block up the holes in the side of the rad with some rags as black stuff dribbled on the carpet is a sod to remove.
    When its empty lift it off the wall and carry outside, remember to block up those holes.
    Take outside and shove a hose in one end hold the rad at 45 degrees and whack with a rubber mallet, the amount of black stuff that ozzes out will be amazing.
    Dont let black stuff onto grass as it will kill it and also stain brick driveways.
    Turn the radiator over and attach the hose to the other end whack untill it runs clear.
    take it back into the house and attach PTFE to the connector threads.
    Hang back on the wall and do up the connectors, open the valves slowly and watch it fill up as you bleed it (dont forget to top up the entire heating system, adding some radiator protector from B&Q will help)
    Keep an eye on those connector joints for a couple of days but most tiny drips stop quite quickly
     
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  12. verytalldave

    verytalldave Hardcore MB Enthusiast

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    As a little "extra" tip when you come to refill the system, add a bottle of 'Fernox' leak sealer.
    This not only does what it says, but it also helps the pump run quieter.
     
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