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Boiler keeps cutting out after leak & no hot water

Discussion in 'Plumbing and Central Heating' started by Stotty1, 2 Sep 2020.

  1. Stotty1

    Stotty1

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    Hi I’m hoping someone may be able to help me, I made a very silly mistake on Monday and drilled a hole in a water pipe while relaying some floorboards.

    I have a gas boiler with an immersion heater, when I hit the pipe I turned off the main water and all three valves I have in the airing cupboard.
    I replaced the pipe and turned all the valves back, the water was off maybe about 2 hours but because the electrics tripped I was not able to test the boiler until yesterday afternoon.

    I turned on the hot water and heating yesterday afternoon and initially all was good but then after maybe half an hour the boiler tripped out, I reset it and it worked maybe 15mins before tripping out again and it keeps doing this.
    All the radiators are getting hot but the hot water is not coming out warm.

    I turned the hot water on again this morning and the pipes sounded awful, I could see them moving, the boiler cut out after a couple of minutes.

    I’m thinking there maybe air in the pipes but I have not idea how to remove it from the hot water.

    If anyone has any ideas on what might be causing the boiler to cut out and water not getting hot please let me know.
    Thanks in advance
     
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  3. ianmcd

    ianmcd

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    post a pic of all the controls, motorised vaves and the hw cylinder, you have an airlock, if we can see what you have we can advise
     
  4. Stotty1

    Stotty1

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    9065603A-97CA-45B9-81C8-01EF836D2B60.jpeg 5DA7A6F2-3FBC-4C0A-BB08-6EE0A710342B.jpeg 78B607C1-A8D5-4517-AE28-0C7B9546A99A.jpeg BF3797F1-6FFA-406E-BD3D-E14C9AD90EA6.jpeg 20ECCAB5-CB9D-4717-B867-1D07D81E5A9F.jpeg Thank you for the reply, I hope the photos are what you are after, do you want me to take the covers off the boiler and take some photos? if you need anymore please ask.
     
  5. ianmcd

    ianmcd

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    you should have either 2 x 2 port motorised valves or 1 x 3 port, can your programmer when working normally allow you to select CH without HW ?
     
  6. Stotty1

    Stotty1

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    Ok I will have a look, I think I know what you mean as I remember a motorised valve in my last house but can’t say I have come across it in this house, but I will follow the pipe work and have another look.
    Yes I can turn the CH on without the HW, although the bathroom radiator comes on when ever the HW is on but when I turn the CH on the bathroom radiator also comes on, so I’m not sure if the CH and HW are connected some how. Hope that makes sense, sorry if I sound stupid
     
  7. Stotty1

    Stotty1

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    A056390E-E496-405E-93D2-EC7627F8C4AB.jpeg A4025D92-AAEA-4BCA-8C2E-7788620D5666.jpeg Is this the motorised valve? It’s not what I was expecting it to look like
     
  8. ianmcd

    ianmcd

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    yes that is it, for future reference that is a 3 port valve and your system is a Y plan, when you are filling your system with that valve you turn the power off at the fused spur, then there is a small latcking leveron the bottom, of the valve at port A, you latch that into the manual position, try that and see if it moves any trapped air, dont do it with the power on though, the pipe from port B if you can follow that to where it connects to the HW cylinder there might be a bleed point there
     
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  9. Stotty1

    Stotty1

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    I had a quick play this morning, turned the power to it off and moved the switch manually, could not hear any sign of air moving.

    Although the manual switch didn’t move as I expected, it moved very easily with pretty much no resistance and didn’t return back to its original position by itself (I had to push it back to the original position).

    I will do a bit more playing when I get home from work.
    Thanks
     
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  11. Stotty1

    Stotty1

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    So looks like I was not pushing the switch far enough, I managed to push it to the end and it springs back if I let go, iv held it open a few times and unfortunately have hear no sign of air moving.
    I have followed the pipe and can’t find any kind of bleed valve

    I have tried turning the hot water on and I can still hear air, sounds like it’s in the boiler.
    Should I leave the motorised valve in the open/manual position?
     
    Last edited: 3 Sep 2020
  12. oldbuffer

    oldbuffer

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    There is a possibility of an airlock in the coil within the hot water cylinder. Hot water from the boiler is sent through this coil when port B on the 3 way valve is open. The normal way to release such an airlock is via an air release valve (manual or automatic) mounted above, and connected to, the top connection to this coil. However, from your pictures there appears to be no access to the top (flow in) or bottom (return) connections to the coil - presumably they are behind the cylinder. You therefore need another way to release this air.

    You could try using a hose connected to the cold mains water (kitchen or outside tap) to force water through the coil. However, to do this successfully it needs to be done with care, and might well require interrupting a pipe run to do it. You may well feel professional help is called for, as the risk of damage outweighs the cost saving.
     
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  13. Stotty1

    Stotty1

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    Iv been thinking more about bleeding the system, I have found 2 drain valves on the system, 1 above the boiler and 1 at the base of the hot water cylinder (pics below).
    If I opened one of these and let them run for a bit do you think it would help shift the air?

    We were hoping to get a new boiler and heating system at the beginning of next year so I’m trying my best not to have to spend a small fortune on this one.

    D6F28DDE-4151-4DC3-8484-92C810319B58.jpeg AD8CDE2A-4139-4418-A594-B547F1E1CD5B.jpeg
     
  14. terryplumb

    terryplumb

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    The drain cock at the base of hot water cylinder will drain the domestic hot water, nothing to do with the central heating problem you have.
    The drain cock above the boiler will drain down the central heating system to the level of the cock.
     
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  15. Stotty1

    Stotty1

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    Thank you for the reply Terry, sorry I haven’t been very clear in my earlier posts, so I seem to have no problem with the central heating side of it, it just seems to be the hot water,
    if I just turn the central heating on all the radiators get hot and the boiler runs fine.
    If I turn the hot water on you can hear the banging and the boiler cuts out after a few mins and needs resetting.

    So my thinking was, if I left all the taps on the system open and opened one of the drain valves the system will keep filling from the loft and hopefully push the air out of the drain valve.
    It’s just a thought I had, not sure wether it would work.
     
  16. ianmcd

    ianmcd

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    NO those are drain cocks and the water that comes out of your taps has nothing to do with your airlock, do as I said earlier and follow the pipe from B in your M/V and post a pic where it enters the HW cylinder
     
  17. terryplumb

    terryplumb

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    The water from the boiler, that gets pumped around your radiators ,also gets pumped around a coiled pipe ,that sits inside your hot water cylinder. The hot water that comes from your taps does not mix with the water from the boiler that runs through the coil
     
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