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Megaflo- how to reinstate air bubble...

Discussion in 'Plumbing and Central Heating' started by miljee, 27 Dec 2014.

  1. miljee

    miljee

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    We have a Megaflow which has lost pressure. The overflow pipe outside isn't dripping, though.

    We have followed the instructions but the lowest hot water tap never stops running! Yes, the mains is well and truly shut off, and yes, the system is 'off'.

    You can see from the photo that this is what the pressure valve (?) looks like. I am wondering if our failure is something to do with that black tap on the flexible hose (to the right of the 'Honeywell' logo) which has been left in an off position. If, whilst they system is on, you turn that tap to 'on', you hear water flowing and the black needle on the dial rises til you shut off the tap... what is it doing??

    We recall we were once told that there was 'additional step' over and above what the printed sticker on the side of the cylinder tells us to do but damned if we can remember what but I suspect it has something to do with this mystery tap, in-line with the expansion chamber (the big red thing, I assume!).

    Any ideas? Be kind, I am a radiographer so can talk you through the physics of an MRI scanner but am less good at domestic plumbing!





     
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  3. Dan Robinson

    Dan Robinson

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    Nothing to do with the Megaflow. . Turn the black knob at the end of the flexible the.

    When the pressure gets to 1.5, turn it back.



    *edit

    Damn autocorreckt
     
  4. dreadnoughtheating

    dreadnoughtheating

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    Suggest that you STOP STOP STOP right there, the big red thing is an expansion vessel for the water in your heating/boiler circuit only, NOT the hot-water that comes out of your taps.

    Can you post a picture of the cylinder itself and the pipework that emanates form it?, and we'll take it from there.

    DH

    Edit, Dan has beaten me to the first reply.
     
  5. miljee

    miljee

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    OK, had another go at it (leaving that black tap alone!). I see the red line on the meter (see original photo) is set at '1' but the black line, the needle, is on 1.75 ish. Presume that's OK??

    Anyway, we did everything according to the instructions, I opened the TPR valve and got about 5 seconds of gurgling, the hot tap stopped running (!) so, so far, so good- but I can't say we've noticed anything other than a slight improvement in the water pressure....
     
  6. ALCPlumbing

    ALCPlumbing

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    If the pressure has reduced significantly I would be looking at the pressure reducing valve. It may just need servicing or worst case replacing. Either way it's not a major job.
     
  7. miljee

    miljee

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    The pressure has improved to what it was prior to this latest attempt- but I'm sure originally you could have cut concrete with it!
     
  8. eveares

    eveares

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    The red tank in your picture is the expansion vessel for your central heating/boiler circuit and not the primary side of your mega flow hot water tank.

    It should never read 0, pressurize it up to 1.5-2 bar when the system is hot by using the black tap on the end of the flexible tube.

    Regarding your issue of the hot water tap continuously running and the mains stop cock being shut off, it sounds like the washers have gone on both of them leaving them open and allowing water to flow.

    The mega flow is pressurized by a valve as shown by the following picture, that may have gone, the valve shown allows you to isolate the cold water supply to the tank and is normally set to 3 bar.

    [​IMG]

    The mega flow also has an expansion vessel, but it is internal to the tank and can't be serviced to my knowledge.

    Also, don't rule out any other issues due to airlocks.
     
  9. OLLIE20

    OLLIE20

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    Jesus I hope you're not in the trade :LOL: :LOL: :LOL: :LOL:
     
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  11. Dan Robinson

    Dan Robinson

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    Worrying innit :LOL:
     
  12. stardanny

    stardanny

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    If you have poor pressure hot water, combi valve will need to be serviced, strainer need cleaning out.

    You will need a G3 plumber to do this sort of work.

    Daniel.
     
  13. OLLIE20

    OLLIE20

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    Mate I rarely even look in here , I only stick to our exclusive club :D , but it was dead in there this morning so I had a venture into the wilderness , I can't understand why people who have a tiny snippet of knowledge at best feel the need to comment like they're an expert :rolleyes: , I'm going back to the warmth of the club , might see you n there later :cool:
     
  14. Steelmasons

    Steelmasons

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    Possibly the megaflo hasn't 'lost it's bubble' as it's quite common for the hot water to run for a good while after isolating hot water tank.

    Higher temperatures will deplete the air gap at a faster rate , common problem with these megaflo's is the 'flying saucer' tipping itself within the unit which again will deplete 'bubble' @ a fast rate.
     
  15. eveares

    eveares

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    No not in the trade - not at all, just the little I self taught my self when I used to have a megaflow tank in my old house.

    What exactly is worrying about my post may I ask?

    If a tap keeps running (hot or cold) when tuned off with water flowing out, what can it be other than the washer or some other component of the tap.

    Also if the mains is off (i.e mains stop cock), the water should stop running once the air bubble has got to its largest size and fully expanded where there should then be no water pressure to push the water out of the top of tank.

    Also the TMP valve connected to the overflow should only drip when the water pressure inside the tank gets to high (10 bar) or the temperature gets to high (90c).

    This may also help you: http://www.heateam.co.uk/docs/replenishing-air-gap-print-instructions.pdf
     
  16. Dan Robinson

    Dan Robinson

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    For a start go back and Google primary water.

    Then read the manuals and tell us what a TMP valve is 'cos I'm damned if I know.
     
  17. eveares

    eveares

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    Can anyone please explain why my last post was deleted again? Not trying to upset anyone here, blame anyone, or cause any tension.
     
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