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4 plumbers down still not sorted

Discussion in 'Plumbing and Central Heating' started by Paul not a plumber, 11 May 2021.

  1. Paul not a plumber

    Paul not a plumber

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    Hi as you can see many of my local plumbers have tried and failed and my missus is getting fed up
    I know this is a slight on the profession but i also know there are some really good plumbers out there i just dont know any local to me (yet)
    We have a shower fed from a thermostatic tap and is in turn fitted with a salamander pump on the hot water side.
    Its a positive pump and will readily trigger itself once shower tap opened so i dont believe its a negative head issue.

    problem-
    It runs for about 30 seconds and then starts to cough and splutter and eventually turns itself off.
    Turning the tap on and offer fixes it and the above repeats, runs for 30 secs or so and then splutters and stops.
    I have bled the pump and as it runs perfect for 20 to 30 secs i think this proves it doesnt have any air locks in the pump itself?
    Sometimes it runs perfectly & can be used as you would expect but more often than not the 30 sec spluttering above happens.
    Its almost like its running out of water or sucking in air.
    I have just discovered that when its running there is almost no HW coming out of the bathroom taps, like they are being starved or something. When it cuts out flow returns to the taps.
    Everything is dry (no leaks) and it appears to have been fitted correctly.
    Its placed at base of HW cylinder with the HW inlet coming from the top of the cylinder where a flange has been fitted.
    The pump is brand new as i swapped it out myself just in case it was that but same thing.
    What can i look at next?
    This has been going on for about 9 months now and like i said a we have had people out who just tend to shrug there shoulders promise to check it out an come back to us but we never hear from them again.
    HELP PLEASE
    20210511_125415.jpg 20210511_125422.jpg
     
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  3. muggles

    muggles

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    Sounds like a blocked cold feed to the cylinder.
     
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  4. Nozzle

    Nozzle

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    Look up vortexing.

    Get the pump suction clear of all of those reducers.

    Nozzle
     
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  5. just pumps

    just pumps

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    If inserts were used in the plastic fantastic pipes then the small bores of them will drastically reduce the flow.
     
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  6. picasso

    picasso

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    Is there a gate valve on the cold feed to the cylinder?
     
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  7. Paul not a plumber

    Paul not a plumber

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    Cold feed blocked, how do i check if this is flowing as well as possible?
    When i flushed the new pump to rid it of air plenty water came through the pump and out the pumps exit hole when i opened the gate valve or would that not prove anything?

    Yes i appear to have a gate valve on the cold feed and it appears to be working fine without any real resistance when turning and its fully open.

    Can you explain this Nozzle? Are you ref where the copper pipe goes into the plastic reducer before going copper again and then flexi anti vibration pipe into pump?

    I am googling Vortexing as i type this !
    many thanks for all your answers and hopefully we can get this sorted once and for all.
     
  8. muggles

    muggles

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    If you have a basin or bath mixer which is fed by mains-pressure cold, you can try flushing it yourself. Clamp your hand tightly over the outlet to stop any water flow, then turn on the hot tap. Now, with the hot tap still on and hand still firmly in place, carefully open up the cold to as much as you can hold back. You'll hear water flowing across the tap (assuming no check valves have been fitted - if they have I'm afraid you'll get a bit wet at this point). Count to 60 then turn the cold off and remove your hand. Let the water run for a minute or so then shut off the hot. Now try the shower again.
     
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  9. Paul not a plumber

    Paul not a plumber

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    I will give that a go and see what happens.
     
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  11. DP

    DP

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    I am wondering if the vent pipe is drawing air when pump runs
     
  12. muggles

    muggles

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    It's on a flange so shouldn't be, unless the dip tube has fallen off
     
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  13. Paul not a plumber

    Paul not a plumber

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    I am watching the thread just not possible to to check anything as at work just now.
    Will try to back flush the cold feed tonight and see if that helps.
    I suppose checking the dip tube is a bit of a pain im guessing? Would that involve removing the flange etc to see into the top of the cylinder?
     
  14. Paul not a plumber

    Paul not a plumber

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    Oh and thank you to everyone who is responding you dont know how exasperated i have become with this!
    Typical in that i am in Newcastle Upon Tyne area and i see you all appear to be based down south !!
     
  15. muggles

    muggles

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    The dip tube should be attached to the flange, so yes it would be removing to check
     
  16. Nozzle

    Nozzle

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    Alarm bells ring on this one - it's not unknown for the actual disc of the valve, and the valve stem to become detached. It means the disc can be "pushed" shut, but not "pulled" open. In the worst case, it means the valve is fully shut, but the spindle position makes you think it's open. It could be anywhere between the two. There should be resistance when opening, friction of the disc over the seat (unless it's a wedge gate, but I doubt it)

    Nozzle
     
  17. dal5band

    dal5band

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    Just a thought, you are mixing pumped HW and mains cold at the mixer tap. Surely the cold mains would back feed into the HW side causing the flow switch in the pump to go off. The effect would be caused by a shower head that restricts the flow, causing back pressure to build up.
    Has this ever worked ?

    (Kitchen taps do not cause this problem as the hot and cold are not mixed and come out of the nozzel seperately.)
     
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