new radiator will not heat up

Discussion in 'Plumbers' Talk' started by tysoup, Jan 18, 2009.

  1. tysoup

    tysoup New Member

    had an upstairs extension and the rad was connected to the exisiting central heating system but has never worked. I decidied to have a tinker recently i bled all the rads and tried shutting off all the upstairs radiators except the one that doesnt work but that didnt cause it to heat up. The pipe up to the left hand valve did warm up but didnt seem to get warm past the valve. I tried draining the system, adding inhibitor and replacing both valves ( both non thermal valves) and flushed the rad. It made the rad warm up but only slightly. I then found a switch to increase the speed on the pump (myson unit five). This resulted in all the rads going really hot except the problem one. When the pipes were laid I remember they were t bars so I guess the water is finding an easier path to go to. Any ideas how i can fix this? I have extended the house so the original system now runs twice as many rads, would a better pump solve my problem? I was looking at a grundfos 15-5- or 15-60 which i assume will be a straight replacement for my unit five (130mm end to end).
     
  2. Captain Leaky

    Captain Leaky New Member

    Have you tried balancing the whole system to try and encourage better flow to the new rad?

    Almost certainly it is just bad plumbing, the water is circulating without going through the new radiator.

    It is nothing to do with the size of pump. Re-plumb the connections and come off the primary circuits if balancing does not work.

    If you don't know how to balance a system just google it.
     
  3. doing a bit

    doing a bit New Member

    is it a one pipe system ?? if so the t eed in piping wont work if its a long length, assuming the valves are opening properly , if you have doubled the system capacity its probably just been extended all over the place , so the original design is gone.:(
     
  4. tackleburger

    tackleburger New Member

    Maybe it's been plumbed in to two returns or two flows so the water isn't going anywhere. Effectively turning the rad into a big cap end.
     
  5. mad.max

    mad.max New Member

    Maybe it's been plumbed in to two returns or two
    flows so the water isn't going anywhere. Effectively
    turning the rad into a big cap end.

    Exactly my thoughts. Either that or a serious blockage, possibly some foreign matter in buried elbow, the matter being in there before installation. (I get the impression it has NEVER worked). Sounds like a replumbing job to me.

    Captain, the OP said he has turned off all rads nd still no joy. Therefore he could balance all day and get nowhere.
     
  6. fronnie_5

    fronnie_5 New Member

    Dont know if ive missed anything but are both valves on the radiator open
     
  7. tysoup

    tysoup New Member

    thanks for all the replies. Yes both valves are open on the problem rad. I will try rebalancing by shuting down all rads upstairs and downstairs to see if that makes a difference now the pump is on high speed.
     
  8. tysoup

    tysoup New Member

    i tried closing all rads and left the heating on for a couple of hours. The problem rad heated up slightly more than before but not enought to warm the room. The flow in pipe was very hot, the rad was warm and the flow out pipe was only luke warm so i suspect there is a problem with the flow out pipework somewhere. Blockage or airlock. Any ideas?
     
  9. bentbolt

    bentbolt New Member

    Back to basics turn off the rad valves and remove the rad or if the air vent is incorporated into a 1/2" plug remove this and fit a 1/2" connector to 15mm and direct it into a bucket or hose pipe.
    turn on one of the rad valves and check the flow then compare it with just the other valve on (if you have a sealed system you will have to make sure someone is topping it up.When doing this make sure some of the other rads are turned on so as to allow water to bi pass any zone/divertor valves may be fitted.
    If you have good flow from both valves as others have said it is probably a one pipe system or both are connected into the flow/return pipe.
    pete
     
  10. mad.max

    mad.max New Member

    Captain, the OP said he has turned off all rads nd
    still no joy. Therefore he could balance all day and
    get nowhere.



    Sorry, Captain. Just re read OP, and I had slightly misread it.- i.e. he'd only turned off upsatairs rads.
     
  11. Lee Nowell

    Lee Nowell Member

    Did you resolve this problem in the end as I have exactly the same problem with almost the same symptoms. The radiator in question also has no 'T's to the valves so have assumed it is the last radiator in the run. In my case, the rad I added was not the "problem one" but the "problem one" was altered from the original as I fitted a bigger rad there.

    In addition, all downstairs rads are fed down the walls from upstairs and they all experience a 2 to 3 hour lag on getting warm (upstairs is about 10 mins) and then not very hot.

    The only other bits of information I can add was that the header tank had a load of sludge in the bottom and thinking it was an airlock, have tried
    -filling from the "problem rad" with mains pressure,
    -running heating with all other rads
    -pump is on full speed
    -ensuring both valves are working

    Any help appreciated.

    thanks
    Lee.
     

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