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Water dripping through Tundish after 2 PRV replacements

Discussion in 'Plumbing and Central Heating' started by Alex Burton, 29 Apr 2021.

  1. Alex Burton

    Alex Burton

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    Hello,

    Wonder if anyone has any ideas or thoughts, i've even spoken to a plumber who is a little confused.We have a unvented Stelflow cylinder which in the past year has had 2 PRV replacement and a temp pressure release valve to. While this stopped the dripping through the tundish initially, after a few months the issue has just come back.

    Does anyone have any ideas what else that could be causing this?!

    I have a water softener and have had a pressure reducing vale (5bar) fitted to the house to. If anyone has any ideas what to check that would be great
     

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  3. Dangee

    Dangee

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    Where is your pressure vessel? It should tee between the combination valve & the cylinder cold feed. Why is your hot water set to 65degrees. The water at the top could be as hot as 85 degrees.
     
  4. Dangee

    Dangee

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    Plus, your other PRV should be at 3 bar. That’s what the cylinder one (in the wrong position) would be at.
     
  5. Dangee

    Dangee

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    Also make sure the water softener is bypassed when filling heating system. Boilers etc font like softened water.
     
  6. Alex Burton

    Alex Burton

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    Thanks for all the replies, ill do my best to answer -

    Where is your pressure vessel? It should tee between the combination valve & the cylinder cold feed. Why is your hot water set to 65degrees. The water at the top could be as hot as 85 degrees. - The expansion vessel is above the tank, i'll grab a pic. The water has always been set like that but its never really hot hot as such. We moved in last year so have mainly just left things as they are. I had an electrician come fit a hive last year and he didnt actually think that thermometer was doing anything.

    Plus, your other PRV should be at 3 bar. That’s what the cylinder one (in the wrong position) would be at. - From looking at the PRV its a 3bar for cold and 6bar for hot ( i think)

    Also make sure the water softener is bypassed when filling heating system. Boilers etc font like softened water. - As far as i know its bypassed. We had the first issue before we had a softener installed in October but the previous owners had a long term softener installed. The water in the tank is softened as far as i know.
     

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  7. Gasguru

    Gasguru

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    That's a really poor installation that doesn't fully comply with the G3 regs. specifically the safety valves and tundish arrangement.
    I suspect there may be other issues leading to the problems you have.
    It's best practice to locate the pressure reducing valve set above the cyclinder to ease maintainance and avoid a cylinder drain down when repairs are necessary.
    Needs a G3 licenced installer to check it out and rectify the faults.
    Download the cylinder manual and check if you have a balanced cold takeoff and whether there's a chance some cold taps are back presurising the cylinder via the hot pipework.
     
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  8. Alex Burton

    Alex Burton

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  9. CBW

    CBW

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    Also looks like the filling loop isn’t fully turned off.
     
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  11. Alex Burton

    Alex Burton

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    which part is that? the braided silver pipe with the 2 black taps?
     
  12. Dangee

    Dangee

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    PRV - pressure reducing valve. Sorry.
    Could you get a photo low down showing the combination valve side on?
    The vessel “might” have been taken from the balanced cold connection & may be the wrong side of the non return valve.
     
  13. Alex Burton

    Alex Burton

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    Here you go
     

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  14. Dangee

    Dangee

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    Is the discharging water hot or cold?
     
  15. Alex Burton

    Alex Burton

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  16. Dangee

    Dangee

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    If you tap the expansion vessel, does it sound hollow or is it a dull thud, like it is full of water?
     
  17. Alex Burton

    Alex Burton

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    Sounds like it’s full to me. I tried to upload a video but appears the forums don’t allow videos
     
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