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Water Coming out of vent pipe

Discussion in 'Plumbing and Central Heating' started by kiltedcamel, 27 Feb 2013.

  1. kiltedcamel

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    Hi,
    My boiler is currently cutting out after a minute or so. It starts banging and sputtering and throwing water out of the vent pipe.

    System - Gloworm fuelsaver 35f, hot water cylinder, 3 port valve, grundfos pump, 4 rads.

    So I'm thinking a couple of things;
    1 - Air lock, but no air is coming out of any of the rads.

    2 - Sludge or other type of blockage. We have an air separator just after the flow pipe comes into the airing cupboard. When the banging starts, I notice the heat travelling up the vent pipe and not towards the pump. Once the banging stops, there is a lot of gurgling in the pipes and the heat eventually travels along to the pump. However by this time the boiler has overheated and cut off, and then the process just repeats itself like this!

    So does anyone have an idea if its no 1 or no 2, or maybe something completely different?

    If it is a sludge blockage, can I do anything about it myself. I have tried to search for a how to on cleaning system.

    Is it drain some water off with hose pipe, add cleaner into small tank, let it run for a few days, then drain and refill with inhibitor?

    Also I'm in a 1st floor flat, the drain valve is at the floor level at bottom of airing cupboard but this is not the lowest point as the boiler flow and return go under the floor.

    Any help much appreciated.
     
  2. Breesey

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    Is the vent pipe the tee nearest to and before the pump or does the cold water feed pipe come in between the vent and the pump?

    Btw are you talking about the drain cock on the bottom of the cylinder? in that picture I mean.
     
  3. seco services

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    Sounds like your air separator is sludged up.

    Try holding a magnet around the air separator see if it sticks.
     
  4. kiltedcamel

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    I have taken a pic but its a bit hard to see.
    The flow from boiler comes in to the air separator. The vent pipe goes straight up from the separator. The other side of the separator (going towards pump) has a feed coming from small tank a couple of inches along, from below.
    If you look in between the 2 pipes in the foreground you can see the pipe exiting the air seperator, then the feed from small tank coming from underneath.

    The pipe then goes to the pump, then to 3 port valve.

    The drain valve is on the heating pipe, i'm not talking about cylinder drain valve

     
  5. kiltedcamel

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    Just tried the magnet and it didn't stick.

    The flow pipe from boiler goes under the floor then about 3 metre along before re appearing at the airing cupboard. Could this lower section be where the blockage might be? As the system was drained a few months ago when replacing 3 port valve. But as this section of pipe is lower than the drain pipe, anything could be in there right?
    I'm just trying to think logically but i'm no heating engineer!
     
  6. Breesey

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    Didn't read 'air seporator' on first read - naughty me!
     
  7. kiltedcamel

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  8. Breesey

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    Most likely place for a blockage or restriction is the air seporator.
     
  9. kiltedcamel

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    Ok so today I bought a system cleaner.
    I drained the system, then before refilling I decided to check the small tank.
    Oh my goodness it had so much gunk in it. Lots of flaky bits, about an inch deep covering most of the floor of the tank, see pic.

    So anyway I cleaned it out as best as I could but its very difficult as there is only a few inches between top of tank and the ceiling!

    I have refilled the system and poured in the cleaner, just letting it circulate now.
    The boiler is still cutting off after 1 min, but the pump is running so I will just leave it circulating overnight.

    What are the chances that this will work?

     
  10. seco services

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    None if it's gone hard like this.
    [​IMG]
     
  11. kiltedcamel

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    So what needs to be done? Powerflush?
     
  12. algas

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    Are you sure that your pump is running, just because its making a noise it doesn't always mean that its ok the impeller could not be turning so not circulating the water, it boils & shoots up the vent pipe.
     
  13. kiltedcamel

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    yes pretty sure its working, I take off screw and insert screwdriver can fell it grinding as it spins.
    plus heat does get through to 3 port after all the banging and gurgling subsides.
     
  14. kiltedcamel

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    Does anyone think using a hose to flush with mains water would help.
    If yes, where would I connect hose and where to drain? I want to try and get the flow pipe from boiler that goes under the floor then into airing cupboard. I have 2 small bleeding points on top of boiler, one on flow one on return. Can I connect hose there?
    also as there was so much crud in feeder tank, how do I know if cold feed is gunked up?
     
  15. TheGasMan26

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    The bit behind the screw still turns when pumps are broken, if its sludged the impellor can become detatched.

    Heat could still make it to the 3 port by heat circulation, or the pump is sometimes just working.

    Id put my money ion your air sep being blocked though, this requires you to cut the pipe out and clear manually, highly unlikely chemicals will work at this stage fella.

    If youv got microbore pipework it could be your manifold(the bit all the pipes come off, will be under floowboards) thats blocked.

    But again, the most likely cause is that your air sep is blocked, needs chopping out, blasting through with a hose/jet washer, and stabbing about with summat long. You will see the ****.
     

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