Glow worm 18sxi gaining pressure

Discussion in 'Plumbers' Talk' started by Alex Jungius, Aug 14, 2015.

  1. What do you mean by 'disconnected'?
  2. Alex Jungius

    Alex Jungius New Member

    Yes, I re-connected the filling loop to stop the dripping from the CH side in the end but had left it off for the entire weekend until yesterday. The pressure increase has gone up. It was 1.1 yesterday morning, increased to 1.4 then remained static overnight with fill and return shut off and since turning on this morning has jumped up to 1.8.
  3. Alex Jungius

    Alex Jungius New Member

    The filling loop was hanging off loose, not even attached to the one way valve on the CH side.
  4. Phew.

    But aargh :).

    I'm not surprised that the pressure jumped rapidly this morn when you opened the isolating valves again, 'cos the pressure is surely certainly coming from the rad side of the whole caboodle, so the rads must have increasing in pressure overnight even tho' the boiler didn't show it ('cos it was disconnected)!

    Ok... :(

    3 remaining options; (1) there IS a mains pipe or some other circuit connected to your rad system even tho' you claim to have checked everything. Or (2) the filling loop isn't as it appears - please post a photo of this part. Or (3) you are hallucinating...
  5. Alex Jungius

    Alex Jungius New Member

    Will post a photo when I get a chance to go back and look at it later. Thanks for your patience.
  6. :) Hey, I'm as curious about this as you are :p
  7. Alex Jungius

    Alex Jungius New Member

    Hi, here is the picture of the filling loop. I've actually managed to stop it leaking by fiddling with it a bit and tightening the wing nut. The pressure still increases though. Weirdly I actually put the heating on last night to give it a run out. Whilst the heating was on the pipe leading from the prove got quite hot so I imagine water is coming out of it. The pressure decreased once the heating was on but then overnight again it's increasing again.

    Attached Files:

  8. That looks ok, and if the pressure still rises when it's completely disconnected then it ain't that.

    So, I'm stumped.

    Only 2 possibilities remain... :rolleyes: (I've discounted the 'loony' one - you seem to be sane and not on stuff you shouldn't be...)

    1) There IS another mains water pipe/fill loop connected somewhere...

    2) You have serious corrosion goin' on inside your rad(s) which is creating gas which in turn is building up pressure.

    Have you tried bleeding every radiator, and did any 'air' come out.

    (Gas from corrosion is likely to be hydrogen, so will burn if ignited. Not sure how 'safe' that test is tho'...)
  9. Alex Jungius

    Alex Jungius New Member

    I bled every radiator in the house on Monday evening and only a little bit of air came out of a few radiators but nothing huge. I may check the pressure manually. Am I right in thinking that the pressure in the expansion vessel should be the same as the pressure of the whole system so if the whole system is saying 2 bar then it should be the same in the expansion vessel?
  10. Hmm, not sure about the water/air pressures in the exp vessel. Certainly when the water side's pressure goes up, the sir one should also go up, but whether they are equal I chust dunno.

    The exp vessel is initially set up with zero pressure on the 'wet' side and then the air side is pressurised up to the right level - about 1 bar (or a shade above). The water side is then pressurised until it is at 1 bar (or slightly over, say 1.2bar).

    What that makes the air side do I just don't know! In theory, if you build up the water side, then the air pressure side should increase - 'cos the rubber diaphragm is pressing against it. But I just don't know :oops:.

    Anyways, it looks as tho' you have no major corrosion, so I am completely stumped I'm afraid.

    What type of pressure gauge does your boiler have - analogue or digital?

    I would certainly try a tyre pressure gauge on the air side (try not to release too much air - press it straight on firmly).

    Compare the displayed 'system' pressure with readings taken from the exp vessel 'air' side. If they both creep up together, then that suggests there genuinely are increases in pressure taking place on the system side :(.

    This ain't rocket science. If the pressure is constantly going up, then something - air from corrosion, or water from a higher pressure area (ie - mains) - is causing it.

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice