Vented central heating system with no vent

Discussion in 'Plumbing and Central Heating' started by jamesr36, 28 Oct 2014.

  1. jamesr36

    jamesr36

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    Hello

    Im doing some work to a house that Ive just bought. Having great difficulty refilling the central heating system. Lots of gurgling noises, only gets hot for the first couple of rads etc.

    Its got a vented central heating system but it doesn't have a vent. ie it has an open gravity fed header tank in the loft feeding the system, all the diagrams Ive seen on google show a vent pipe from the boiler flow which hangs over the top of the header tank. This is not there. Is this normal or could it be the reason for my refilling problems?

    The HWC has a vent pipe as normal

    The house is 1990s and a house builder type house so must be a professional installation. I can easily add a vent but it must have worked okay for the last 20 years and a bit reluctant to alter a pro fitted system.

    Thanks in advance
     
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  3. Tibbot

    Tibbot

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    Probably combined feed & vent (22mm pipe). Make sure it rises continually towards tank. A pain to release all air. You may have to wedge up any pipe sections that fall the wrong way.
     
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  4. jamesr36

    jamesr36

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    Thanks. It is a 22mm pipe. I will have another look at it tomorrow to see if there are any sections falling the wrong way.

    Adding a vent is a fairly easy job. Would adding one be worth doing?
     
  5. 45yearsagasman

    45yearsagasman

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    It's probably been done like this. Quite common and as said sometimes a pig to vent. You may be able to fit a manual air vent on the system high point to assist with refilling.
     
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  6. jamesr36

    jamesr36

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    Thanks for your reply. That diagram is as installed but with no air release valve. The only air release valve is between the motorised valve and the coil inside the HWC.

    There is no air in any of the rads or if I undo this valve but it is in there somewhere as it makes a lot of gurgling/sloshing noises and the boiler keeps cutting out.
     
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  8. Armo74

    Armo74

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    Could be a magnatite problem then causing circulation problems and giving off hydrogen.
     
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  9. Scarum

    Scarum

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    Same set up as me.

    Is it gurgling when heating hot water only? Is it a gugling or kettling sound?
     
  10. Agile

    Agile

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    Run heating and close one valve on each rad leaving at least a minute between each one.

    Then open them and see if any difference.

    Its quicker and cheaper to use a combined F&E.

    Tony
     
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  11. jamesr36

    jamesr36

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    I think it's fixed. It does have a combined feed and vent pipe and in the loft there was a long length of it fixed level.

    I chocked up the header tank a couple of inches so that the pipe had a fall and now all seems to work

    Thanks for everyone's help
     
  12. DIYnot Local

    DIYnot Local

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