Posting a message to the forum will remove the above advertisement
  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. Checkout our Plumbers Insurance area - heavily discounted Public Liability Insurance and Van Insurance specifically designed for plumbers.

Is this pressure ok?

Discussion in 'Plumbing Forum' started by DanUK, May 17, 2018.

Discuss Is this pressure ok? in the Plumbing Forum area at

  1. DanUK

    DanUK Member

    Hi all, I hope you can put my mind at ease please!

    I have an unvented system at home and recently the gauge pressure reading has been above 3psi if I haven’t been home all day, up to 3.5. Previously it always stayed at or below 3psi. I was told before it shouldn’t go above 3.

    Having checked the pressure valves they state 6psi though so was I told incorrect information? I’ve attached some pics.

    Thanks in advance,



  2. DanUK

    DanUK Member

    This one shows the piping too!

  3. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    normally 3-3.5 bar (depending on what the prv is set to) is normal the water board could of upped your pressure
  4. DanUK

    DanUK Member

    Thanks! By the valves though is it safe to go up to 6psi / when should I worry and call a plumber?
  5. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    should stay around 3-3.5 bar, any time you see water coming through the black plastic tundish (follow the pipes from the red safety valves you should see a black thing) then you would need to call a g3 plumber

    when was the last time you had the cylinder serviced?
    • Optimistic Optimistic x 1
  6. DanUK

    DanUK Member

    Thanks. Yep I’ve seen that before and had to have some bits done to it (can’t remember what) but that was about 9 months ago.

    Out of curiosity why is it between 3-3.5 If the red valves have 6psi or 7psi on them?

    Thanks for your help!
  7. Best

    Best Trusted Plumber

    The pressure relief valves are at bar pressure opening.
    They are higher than operating pressure, so not to open at normal pressures, but will open at the higher pressures which are getting near units safety limit. There is also a heat limit release there.
    There could be a fault causing slight increase of pressure and due to lack of proper service
    Get your G3 service person to explain it to you while they service it now
    • Like Like x 1
  8. DanUK

    DanUK Member

    Ah thanks.

    So based on what I’ve sent it looks okay as long as it doesn’t go above 3.5? The tundish is fine.

  9. Best

    Best Trusted Plumber

    Actually I now have doubt about that install. But I could be wrong, as photos don’t show it all.
    Does the pipe with the stopcock drop down and connect to bottom of cylinder ?
    • Like Like x 1
  10. DanUK

    DanUK Member

  11. Best

    Best Trusted Plumber

    I can’t download the video files on Apple, but maybe someone else will take a look at what the stopcock does
    • Agree Agree x 1
  12. DanUK

    DanUK Member

    • Optimistic Optimistic x 1
  13. Best

    Best Trusted Plumber

    A few things I have noticed.
    The stopcock I think should not be installed between the cylinder and the combination valve due to the relief valve would be isolated.
    Also, -
    The balanced cold could have been taken from combination balanced connection, rather than appearing to be taken after the combination valve
    Also, -
    Discharge pipes and tundish - where are they? Tundish must be within 600mm of cylinder temperature and pressure relief valve. And tundish must be visible. Maybe it is just not in photo
    Shaun might clarify if I am correct
  14. DanUK

    DanUK Member

    Thanks! That all sounds bad? I’m not that upskilled in plumbing to know what that means.

    The tundish is the other side of the boiler connected to this valve (see pics).

    Should I be worried? Can I assume it’s ok if the pressure isn’t above 3.5?


  15. DanUK

    DanUK Member

    P.s. there are 2 stopcocks. See first pic. That’s the main one - then one further down
Similar Threads - pressure Forum Date
WB HEATSLAVE 18 25 losing pressure Central Heating Forum Thursday at 9:22 AM
Solution for low head pressure. Bathrooms, Showers and Wetrooms May 19, 2019