Cold radiator, Gravity fed system

Discussion in 'Plumbers' Talk' started by gabr1101, Jan 22, 2011.

  1. gabr1101

    gabr1101 New Member

    I have a gravity fed hot water system in my house, I have discovered a problem with a cold radiatior in my spare small bedroom on the first floor.  All the other 10 radiators in the house on the ground and first floor are red hot except for the one radiatior in the little room.  I have bled the air from all the radiators so water just flows from them.  I bled the system just before it kicked in and heated up.  I checked the pipes feeding the hot radiators and they are red hot, the pipe feeding the problem radiator is 'warm' and does not get hotter than that.  All the radiators have been fine for the past 5 years, the problem has only started in the past 3months.   Any help advice as to what the problem is , will appreciataed.
     
  2. midnight cowboy

    midnight cowboy New Member

    If the radiator has a TRV the pin may have stuck.
     
  3. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    Have you tried stopping the other radiators ?

    Mr. HandyAndy - Really
     
  4. gabr1101

    gabr1101 New Member

    Turned all the other radiators off and left the cold one open, turned on the boiler but it did not heat up the radiator, Tried to bleed the radiator again but no joy.
    Yes the radiators all have TRV's on them, I have taken the top off the TRV, squirted the pin with wd40 and hit it a couple of times with a hammer, it springs up and down ok.
    Any more ideas appreciated
     
  5. midnight cowboy

    midnight cowboy New Member

    Is the lockshield valve on the other side  open enough?

    Failing that it will be a blockage in the pipework or the radiator.
     
  6. gabr1101

    gabr1101 New Member

    The lockshield valve has not been touched as all radiators were fine about 3 months. I currently have all radiators turned off except the cold one and the one closest to the boiler as when i bleed the one closed to the boiler a small amount of air comes out everytime I do it.
     
  7. If the radiator is running on 10mm or 8mm pipes sounds like you have a blockage in the pipework leading to that radiator, that is most likely your problem as not often 15mm pipework gets blocked.
     
  8. midnight cowboy

    midnight cowboy New Member

    I'm sure the lockshield hasn't been touched! but 999 peeps out of a 1000  would take the cap off and rotate the valve  anti-clockwise just to make sure it's opened enough.  
     
  9. Crowsfoot

    Crowsfoot Screwfix Select

    I would swop the TRV for a manual wheel headed valve.
    Even though the pin is moving it may not be lifting the plunger inside the valve.
    One thing you could try is if the valve pin is of the type that goes through a gland nut, then give that gland nut a half turn anti-clockwise (sometimes releases it)
    TRVs are problematic.
     
  10. gabr1101

    gabr1101 New Member

    Tried turning the lockshield valve half a turn and also the gland nut under the TRV and it does not appear to of freed the problem.  Its looking like a blockage in the pipework I, I guess I will need to get a local plumber and assume the system will need flushing/draining through?
     
  11. Depending on your level of competence you could try draining the system and removing the radiator in question and connect the pipework to water mains pressure to see if the pipes are blocked this may well force the obstruction through if there is one. Putting a flushing chemical into the system in my experience is unlikely to clear any pipes that are total blocked. Please don't embark on this course of action if you are unsure of anything as there is plenty of things that could go wrong!!
     
  12. Pusscatty

    Pusscatty New Member

    I have one radiator in the bathroom which works on a gravity feed system. The hot water is supplied by a solid fuel Morso stove with back boiler. Recently the stove was serviced and anti-corrosion treatment added just as a precaution against future problems. A new ball valve was also fitted in the feeder tank. The stove still heats the water OK but ever since the service took place, the radiator has not worked at all. Both valves are open, it's been bled twice, still no joy. The service was carried out by qualified engineers who have been back but failed to fix it. What could could the problem be?
     
  13. Crowsfoot

    Crowsfoot Screwfix Select

    Most likely an air lock in the pipework. Make up a good fire and you should be able to boil it out.
     
  14. Pusscatty

    Pusscatty New Member

    I have had a fire going for a week now. The water is VERY hot in the taps, and also in the pipes which come out at the bottom of the hot water tank. It just won't reach the radiator. Nothing has changed since the boiler service, except the addition of the anti-corrosion treatment and a new ball valve on the feed and expansion tank (which appears to be working OK). The stove engineer/plumber has tried everything. He took the radiator right off today and flushed it outdoors with a hosepipe - not much muck, just grey water. The radiator went lukewarm for 10 mins after he replaced it but it's stone cold again now. Poor lad lives 18 miles away so I hate having to call him out, and he's at his wits' end trying to figure out the problem. There is no TRV, just ordinary on/off valves on the radiator pipes.
    PLEASE SOMEONE REPLY. I need warmth in my bathroom before winter!
     
    Last edited: Sep 29, 2014

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