Help! Some Radiators not Heating up – What can I do to Fix this?

Discussion in 'Plumbers' Talk' started by v1nce, Dec 6, 2018.

  1. v1nce

    v1nce New Member

    Hi, hope you knowledgeable folk can help as I’m a total novice when it comes to plumbing.

    I’ve got 13 radiators in my house and a few of them are not heating up. At the moment when going into Bedroom 3 on the g/f is like walking into the artic. If however I turn off 10 radiators (numbers 1 – 10) at the TVR side (right side when looking straight on) then the remaining 3 radiators (11, 12 & 13) start to warm up.

    I’ve bled all the radiators and the only one that ever seems to have any build-up of air is Radiator 1.

    The house was extended/ensuite added a few years before I purchased it and additional radiators were added at the time to the newly created areas (not sure if the pipe work to them was run from the manifold which is on the 1st floor or the supply taken from the nearest older radiator).

    I should add that my central heating system is actually a mix of microbore and normal pipes. 7 radiators on the g/f (4-10) have microbore pipes. The three problem radiators (new ones) all have normal pipes. Also all 3 radiators on the 1st floor also have normal pipes.

    Last night I tried to establish which radiators come on first and played around with their lockshield valves. Currently 10 Radiators (numbers 1 – 10) have their lockshield valves open a ¼ turn. 11 is open ¾ turn, 12 is open 1.5 turns and 13 is fully open. Prior to me doing this radiators 11,12 & 13 were stone cold. So my tinkering around has been of some benefit as 11 & 12 are heating a little (13 is still stone cold).


    In the diagram I’ve numbered the radiators in the order which I believe they warm up first (with the exception of number 3 on the 1st floor which may be feed from down below, number 11). I’ve also put in a percentage of how much of the radiator gets hot (from top downwards).

    What do I need to do to get radiators 11,12 & 13 working again?

    Appreciate any help. Radiators.jpg Radiators.jpg
  2. KIAB

    KIAB Well-Known Member

    Sounds like a balancing issue, you need radiators nearest to the boiler will have the valves almost closed off, & the radiators furthest away will have a valve probably close to fully open.

    Can have no end of grief with 8mm,10mm microbore,flow rates, crud blocking, & 15mm pipe.

    What boiler you got, it's age, & does it have a magnetic filter fitted
    Last edited: Dec 6, 2018
  3. v1nce

    v1nce New Member

    I had a new boiler fitted when I purchased the house last summer (the old combi had stopped working). The boiler is a Valliant ecoFit Pure 430 (open vent) & at the same time a MagnaClean Pro filter was also installed.

    The 3 problem radiators all work when the others are off.

    I’m not even sure if there is a possibility that the rad’s with normal pipes are feeding the problem rad’s on the ground floor (as all 3 of them also have normal pipes). 1 > 2 > 3 > 11 > 12 > 13
  4. Jimbo

    Jimbo Active Member

    Turn the lock shield down on all the others half a turn and up on the problem three, reheat and repeat as required.

    When you first turn on the system you might find one in particular warns up much more quickly, turn that down more at the lock shield.
  5. ajohn

    ajohn Active Member

    As the problem is with the added radiators that is probably the cause of the problem - where they get the water from.

    Maybe an answer is to set up the old ones first with new turned off. Then open up the new ones and see what happens. Each may interfere with one or more of heat getting to the old ones. If nothing close each of the old radiators lock shield valve on the old ones up a bit in turn until the new ones seem to be getting heat.

    Problem is that the new radiators may have been linked in by doubling up on the old feeds to the old radiators. Less pipe and problems that way.

    I balanced our system up by running around the house while they were warming up. Went for evenly downstairs and a bit of a lag upstairs. TRV's upstairs are always set lower anyway in our case. I saw a much more scientific method when the gas board as it was then installed my parents central heating many years ago. They had a gizmo with two clips. Placed one on one pipe to the radiator and other on the other pipe to the same radiator. Then set the lockshield for a certain temperature difference. This way one radiator was set up at a time. What ever it was they did it worked although in some ways it doesn't make sense.

  6. The Teach

    The Teach Well-Known Member

    bra.jpg Its a standard method of setting up radiators, bra.jpg removing the trv sensor while balancing is necessary. Then job done :)

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  7. KIAB

    KIAB Well-Known Member

    I use digital differential 2 channel thermometer,easier on the eyes to read.:)
  8. ajohn

    ajohn Active Member

    When I saw it done by West Midlands gas was really a long time ago, could be more than 40 years ago and probably was. One thing I noticed was that it was built in an electronics style project box so they probably made it themselves. It was new to the "workers" and they didn't think it was working - the man in the suite said carry on adjusting.

    It clipped on with Terry clips so is suspect it used thermocouples. Must admit it's such a pain to do I could be tempted if cheap enough as it's such a pain to do. I know ours need re adjusting since I took a radiator off - it was fully open so some one had messed with it.

    I assume adjustment can be started with the lock shields fully open?

  9. ajohn

    ajohn Active Member

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