Baxi Boiler Losing Pressure

Discussion in 'Plumbers' Talk' started by Susantootsies, Oct 6, 2008.

  1. Susantootsies

    Susantootsies New Member

    Hi again ... thanks for the info -- am perplexed as to why our plumber hasn't done this already to rule out the pipework ... as everything's pointing to a leak in the pipes apart from the "expert" who did the testing with the hydrogen gas and said its OK ... but judging by reactions on this thread no-one seems to put much store by the "experts" evaluation .... can you let me know how much we shoudl expect to pay for a plumber to carry out this test for us ...we are Surrey/London borders .... it would be good to get this done so we can finally track down if the "expert" was wrong and it is the pipes, or whether it is the boiler .... thank you so much for your help on this one .... really hope its the boiler so we dont'have to carve up new floors .... Yikes !! Susan
     
  2. ripitout

    ripitout New Member

    why bother doing a wet test at 3 bar? the system has been proved to be leaking at 2bar water pressure.

    how far are you from esher susie?
     
  3. graceland

    graceland Active Member

    just discovered this thread, like a soap opera!
    what happened in the end, i must know!!!lol
     
  4. lana

    lana New Member

    Hi

    I know it may be a long shot but, would anybody know what the outcome was re this post?  I have exactly the same problem (I'm on gas man number four). Nobody seems to be able to find why the boiler is losing pressure.  I think we have a leaky under the floor but none of the guys I have had to investigate seem to agree.

    Many thanks

    Lana
     
  5. Dave does Gas

    Dave does Gas Screwfix Select

    Lana

    One of the first things you should try if you no longer need the heating on is to top it up to 1.5 bar then underneath the boiler isolate the flow and return pipes. Ensure that there is no demand for the heating at all. boiler switched to summer, timer off, room stat down low. Give it 48 hours or so, check the guage it should still read 1.5 bar. Now open the isolating valves on the flow and return, if the pressue instantly drops then you definatly have a leak on the heating circuit.

    Dave
     
  6. lana

    lana New Member

    Hi Dave

    I did as requested.....the pressure dropped to zero within the hour....the last gas man hasn't come back!  I think I have a leak under my concreate kitchen floor.  When I top the boiler up you can see the pressure dropping almost in front of your eyes.

    Any ideas what I can do next, I just don't know what to do.

    Many thanks

    Lana
     
  7. Dave does Gas

    Dave does Gas Screwfix Select

    This is the tricky bit, if you are certain the leak is under the concrete floor the simple amswer is to have that section re-piped running the pipes on the surface if that is possible, of finding a way to re -route the pipes cutting out the affected section.
    Best thing you can do is find a reliable plumber and get his advice. One way to confirm the leak under the floor is to get in a firm who do thermo imaging, they can trace the pipes and identify the leak site but it is not cheap around the £400 mark.
    Sorry to be the bearer of bad news but Im afraid this is relativly common with copper pipes in screed not adequatly protected.

    Dave
     
  8. lana

    lana New Member

    Hi Dave

    Thank you for the information, it is much appreciated.  I am going to find a plummer and not let him out until he fixes the problem! 

    Kind regards


    Lana
     
  9. wetpants

    wetpants New Member

    Probably worth getting somebody with a thermal Imaging camera to pinpoint where the leak is under the screed, might be a long shot, but could be worth it.;)
     
  10. kevin walker

    kevin walker New Member

    Where combination boilers accommodate the thermal expansion of the CH system (hot water increases in volume) by the use an expansion vessel. This a basically a vessel in which there is a rubber bladder that is charged to a pressure, and as the CH system pressure increases (due to heat) the bladder is compressed, and this increases the volume available to the CH system. Therefore if the bladder charge pressure falls (bellow the preset or zero) there is less ‘expansion volume for the CH system.
    The consequence of this is as the CH system gets hot the pressure increases (as there is no spare volume) and this may cause the emergency release valve to operate (3Bar). This releases the pressure & thereby CH system water volume. Once the system cools there is insufficient CH system water and therefore a reduced base pressure.
    As a product of the above I would check the expansion vessel pre charge pressure, via the schrader valve on the unit
     
    alan gladwin likes this.
  11. Dave does Gas

    Dave does Gas Screwfix Select

    Hi Kev,
    Why are you digging up a post from 2013?
     
  12. kevin walker

    kevin walker New Member

    the only reason is that I suffered the same issue, and I didn’t see a closure in these posts, so I thought I'd do the right thing and post a solution
     
    Mosaix and Dave does Gas like this.
  13. Russell Stimson

    Russell Stimson New Member

    Hello, can anybody give advice on my Baxi Solo boiler problems
     
  14. Russell Stimson

    Russell Stimson New Member

    I will give a very bad description and leave for comments. The boiler appears to get the hot water and central heating to,their desired temperatures, then it trips in and out constantly, it sounds like the boiler is working four times as much as it should
     
  15. michael vitesse 6

    michael vitesse 6 New Member

    As a gas safe engineer i would do as previously suggested...test the integrity of the boiler when cold by topping up to 1.5 bar,then shut boiler flow and return valves under boiler this will isolate problem to pipework or boiler,having done this let the pressure down to zero and test the pressure vessel with a tyre gauge...1 bar is what it should be...unfortunately the schrader valve is on the top of the vessel and not readily accessible
     
  16. michael vitesse 6

    michael vitesse 6 New Member

    sorry didnt read all the threads...if the boiler pressure stays up with valves isolated then it is the pipework...your plumber could install a tee into the flow or return pipework with a pressure gauge,again isolate the boiler and observe the pipoework pressure gauge....have had this problem twice in my career,1 st was down to sacrificial anode effect and pipework was porous,second just a fluxed but not soldered joint which had held for years till a sealed system and increased pressureses...i have had huge success with infra red cameras from contractors to spot leaks quickly in solid floors
     
  17. Dak

    Dak New Member

    I know this an old thread but I'm having a real mare with same issues. Boiler will not hold pressure when cold. After 4 plumbers/heating engineers looking at it I'm none the wiser. I'm at this stage now have pressurised boiler isolated it and it's still going from 1.5 to zero within 2 hours. Bag on pipe outside is not showing water no visible signs of water anywhere. Sorry for non technical terminology I'm a complete novice !! Please help
     
  18. Samz

    Samz New Member


    Hello Mate

    Just read ur thread....what was the outcome?
    Our Baxi boiler 6mths old....pressure dropping at all the time.
    Paid for trace & find & no leaks!
    Baxi changed heat exchanger & tiny bit of rust on it...but still leaking!
    Baxi man at a loss, as are we...
    The condenser pipe in garden is now constantly dripping-even when boiler off.

    HELP PLS
     
  19. Hi Samz.

    Always best to start yer own thread.

    However, there's a few things we can say...

    If water is trickling oot yer condensate pipe with the pressure dropping all of the time, that's quite an indicator. The leak must surely be coming from inside the main heat exchanger (called heat 'engine' these days... :rolleyes: )

    This is because the condensate pipe leads out from the bottom of that whole exchanger/combustion chamber box, and the only water going through it is 'system' water, which is the sealed pressurised stuff. (Unless rain is getting in the flue pipe).

    They've replaced the main exchanger? Well get them to do so again...

    But, really, it's as simple as this - the boiler is 6 months old, you are a layman so don't need to understand the cause; they need to fix it. End of.

    When you say 'Baxi' man, was he a person sent out by Baxi? And is this the same cove who fitted the boiler?
     
  20. Samz

    Samz New Member

    Thanks 4 ur reply.

    Im new to this site & wasnt aware of starting a new thread.

    The baxi man is a different person to the installer.
    The installer suggested he put some leak 'stuff ' into the boiler so if there was a leak it would seal it....he did this twice & then called the baxi man as it didn't work.

    Looking on Google we wonder if could be the expansion vessel?

    The trace & find man thought it was due to the installer never bleeding all the rads. He bled them & all was ok for 5 days.
    BUT, 1 of the rads was half cold & hot. So bled it & here we go again with loss if pressure!
     

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