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Discuss Changing 3 Port Valve On Bungs in the Central Heating Forum area at

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  1. plumbandplumber

    plumbandplumber Member

    After a bit of advice please. System is completely conventional OV, 2 tanks, 3 port, etc.

    Firstly, is it possible and advisable to change the 3 port valve on f & e bungs?

    Secondly, I have the conical, rubber bungs, but the outlet for tank has splines in it. How can I get good seal with these bungs?

    Lastly, any tips and advice re. bunging and changing the valve would be great - to avoid a tsunami! :bigcry:
  2. Chalked

    Chalked Plumber GSR

    Don't want to stat the obvious, but wouldn't it be quicker and safer just to drain down? You will still have to bleed the system after using the bungs! :confused5:
    • Like Like x 2
  3. BLOD

    BLOD Plumber GSR

    use a lump of plumbers mate in an old flannnel, you can manipulate it into the right shape
  4. Rickster123

    Rickster123 Guest

    Ive never really understood the fascination with bunging the system. Drain down takes no time at all.
    • Like Like x 1
  5. Millsy 82

    Millsy 82 Plumber GSR

    I'm like that as well. When I'm draining I wire in the new valve. Then when it's filling I'm having a cup of tea.
    • Like Like x 1
  6. Ch4 plumbing

    Ch4 plumbing Plumber GSR

    Really? I use them all the time and if your careful they are much quicker then draining down, plus you don't have to reload the inhibitor.
  7. bigads28

    bigads28 Guest

    I use bungs all the time too, some systems lock up just like that and them some you wonder why you didn't just drain it! 3 ports can some times be a pest because you have 3 open pipes where the air lock can break. Make sure you have everything you need to install the new valve to hand.

    If you aren't confident and it will cause damage if the lock breaks then just drain it.
    • Like Like x 2
  8. plumben

    plumben Plumber

    I see the advantage of bungs but personally I drain down and give the system the benefit of a flush whilst doing the work
  9. PriestyUK

    PriestyUK GSR

    Bung it all the way, specially if its a old system, don't want any crap sucking down the cold feed from the bottom of the F & E tank now, oooooo the panic on the faces of plumbers when they try to fill up and nothings happening
    • Like Like x 1
  10. Aquazone

    Aquazone GSR

    Same. Usually bung it, turn off top pump valve if gate type to leave 2 open ends. Crack nut on valve and into a bag. Usually about a pint. Much quicker than draining.

    Although I've seen some lads trying to bung 2 floors to change a heat exchanger on a Fleixicom. Told him not to. Sooooooo funny
    • Like Like x 2
  11. plumbandplumber

    plumbandplumber Member

    Thanks for your replies. It's an ancient system that's been added to over the years and has been a real problem with airlocks in the past. I would like to bung if I can.

    With bunging the F&E outlet and the splines, would a carrier bag over the bung work?

    Any other tips appreciated. Thanks to all.
  12. Millsy 82

    Millsy 82 Plumber GSR

    I find it doesnt take that long to drain and swap a valve on most systems. As soon as I hear it gurgle past the pump etc then whip valve out change nuts put new in wallop inhibitor in the f and e although not much water would of been drained turn water back on, by now my cup of tea will be the right temperature so slurp my tea whilst bleeding the pump and thumb vents in airing cupboard turn on and test. usually 40mins to an hour.
  13. Millsy 82

    Millsy 82 Plumber GSR

    I look at the cold feed and vent before I give my price as alot of the time it is that that gives the most problems with airlocks.
    • Like Like x 1
  14. happyflyer

    happyflyer Guest

    Bungs my ass, a 3 post valve is a pig to change normally, where did this bung bit ever come from, what the hell is wrong with draining down, air will get in somewhere and let water out its not for the DIYER.

    If you get air locks when you fill up there is something wrong in the pipe levels, get it fixed once and for all, usually in the roof on the CF from the tank out of level, poor plumbing, don't run away from problems, like "this system always air locks when you fill it it" like a bad doctor
    Last edited by a moderator: Sep 11, 2014
  15. happyflyer

    happyflyer Guest

    100 out of 10
  16. lame plumber

    lame plumber Guest

    just change the motor head if the valve moves ok, ok 9/10 times :)
  17. MC_Bob

    MC_Bob Member

    No. Change both. Its a ripoff changing the motor and not the body. People dont realise its the body not moving all the way around which stops the motors hitting the microswitch.
    Fit a new head and wiggle the body, sure its going to work until you collect the money..
    • Like Like x 1
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