Is there more than one type of 22mm thread?

Discussion in 'Plumbers' Talk' started by alanterrill, Aug 30, 2019.

  1. alanterrill

    alanterrill Member

    I need to connect to a 22mm femaile thead on my heat pump. I've bought a couple of different fittings from Screwfix both of which have a 22mm thread on one end but neither will fit the 22mm compression fitting on my heat pump. The pipe slides into the fitting and the nut will rotate about one turn but then jams. Looking at the two side by side, the thread on the screwfix fitting is broader than the thread on the one in my heat pump. Can anyone tell me what the top one is called and where I might get a fitting for it?
    [​IMG]
     
  2. KIAB

    KIAB Well-Known Member

    It will be a BSP (British Standard Pipe) thread,3/4" most likely, not a metric thread.
     
  3. nigel willson

    nigel willson Well-Known Member

    They aren’t 22mm threads. Threads are not metric they are imperial. The wonders of our plumbing system I’m afraid. That will probably be 3/4 inch. Problem is some manufacturers use there own thread patterns
     
    KIAB likes this.
  4. terrymac

    terrymac Well-Known Member

    QUOTE="nigel willson, post: 1735053, member: 105972"]They aren’t 22mm threads. Threads are not metric they are imperial. The wonders of our plumbing system I’m afraid. That will probably be 3/4 inch. Problem is some manufacturers use there own thread patterns[/QUOTE]
    ..................
    There are certainly metric threads ,and the thread looks more like metric than imperial on the heat pump. Where did you get the pump from ,is it U.S.A ?
    The threads on the brass are not 22 mm.
     
    Last edited: Aug 30, 2019
  5. alanterrill

    alanterrill Member

    The heat pump is an IVT made in Germany I think. Its not a 3/4 bsp as I've tried those and the internal diameter is too small (the right hand half of the fitting on the bottom of my photo is 3/4" BSP) and it won't fit over the 22mm pipe.
     
  6. nigel willson

    nigel willson Well-Known Member

    ..................
    There are certainly metric threads ,and the thread looks more like metric than imperial on the heat pump. Where did you get the pump from ,is it U.S.A ?
    The threads on the brass are not 22 mm.[/QUOTE]
    I had to get something wrong for once! Lo
     
    terrymac likes this.
  7. terrymac

    terrymac Well-Known Member

    What fittings are on the other ports of the valve ? You should have gotten the fittings with the pump. You could always contact the manufacturers for parts. I doubt you will get what you need in any UK plumbers merchants. 22 mm metric threads are not exactly in demand in the UK.
     
  8. longboat

    longboat Well-Known Member

    Thats a funny looking heat pump.
    Are you sure its not a 3 port zone valve, which would also incidentally explain the different types of thread used.
     
  9. alanterrill

    alanterrill Member

    Longboat - that is a 3 port valve that switches between the hot water tank or the radiators -it's within the heat pump.
    And to Terrymac -I've not detached the other ports on the valve but they all look the same. I did get all the fittings with the pump. The problem is I've got a partial blockage within the unit and want to flush it out -The best way in is to disconnect a flexible hose near the top of the tank which is the hose that connects to the 3 way valve, but I then need to connect a hose to a mains water supply and the female half of the compression joint but I can't find anything that will give me a watertight seal.
     
  10. terrymac

    terrymac Well-Known Member

    So you have a nut and olive then ,which connects a 22 mm copper pipe to the valve ? Or is it a flange for a hose ?
     
  11. alanterrill

    alanterrill Member

    Its a nut and olive on a piece of22mm copper pipe attached to a flexible metal hose.
     
  12. terrymac

    terrymac Well-Known Member

    So ,can you use the nut ,with a new olive and a short piece of 22 mm copper to connect to the valve port ? So you then have a 22mm copper pipe that you can connect all kinds of things to.
    And what fitting is on the other end of the flexi ?
     
  13. alanterrill

    alanterrill Member

    Yes I already have a short piece of 22mm copper pipe sticking out beyond the olive, but I don't want to attach anything to it that can't be removed without damaging the pipe as I have to reconnect it to the three way valve once I've flushed it through, and may want to do so again in the future. I'm thinking I may try a 22mm plastic push fit joint that I can remove afterwards.
     
  14. terrymac

    terrymac Well-Known Member

    Maybe I haven't explained well ,or I am missing the point. Take the nut and olive off the pipe ,and fit to a new piece of pipe ,which you can connect multiple things to .
    Aren't you trying to connect something to the port in your pic ,that you can then connect a hose pipe to ,or am I totally misunderstanding ?
     
  15. heatyman

    heatyman Well-Known Member

    Remove the olive from the pipe you've removed. Remove the nut originally fitted to the valve and with a new olive, make up your connection pipe. When finished, you will need a new olive to reconnect the original pipe.
     
  16. alanterrill

    alanterrill Member

    I understand what you're both saying -but how do I remove an olive? My experience is that when an olive has been in compression for some time (and in this case 18 years) it makes a dent in the copper pipe and can't be slid off. I can't afford to damage the pipe as it is part of a complete hose i can't replace. See pictures.
    [​IMG]

    [​IMG]
     
  17. Hans_25

    Hans_25 Active Member

    Can use an olive puller, or *very carefully* cut it off with a junior hacksaw. The copper pipe shouldn't be damaged at all, put on new olive and a smear of jointing compound for good measure.
     
  18. alanterrill

    alanterrill Member

    Thanks - I just looked up olive pullers and all the sub £20 ones use a threaded end to attach the the nut which guess what? - has a different thread :) . Looks like I'll have to invest in a £27 pliers type if I really want to do this.
     
  19. Hans_25

    Hans_25 Active Member

    You could just cut it off with a hacksaw - don't need to saw all the way though, use a screwdriver or other implement when its most of the way through to break it in half.
     
    terrymac likes this.
  20. terrymac

    terrymac Well-Known Member

    If a compression joint is severely overtightened ,then your right it can damage / crush the pipe. When the olive is removed you will see the damage to the pipe. Looking at your pic it appears to me that this is not the case ,there is every chance that you can knock the back of the nut with a spanner and the olive will come off quite easy. I would certainly try that before taking a hacksaw to it.
    Very ,very ,carefully cutting the olive with a junior hacksaw would have it off in no time. If the pipe is indented you can solder on a coupler with a short length of copper anyway.
     

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