Acceptable gas pressure drop between meter and boiler?

Discussion in 'Plumbers' Talk' started by Gordon S, Apr 10, 2008.

  1. silversurfer$$

    silversurfer$$ New Member

    The boiler is under gassed by .9 of a mb if worcester are asking for 18, firstly you should have had a vailant as they only req 17 mg then you would be spot on.(sorry only joking)

    The classification of the instilation will be "[Not to current standards" un less there is an unstable flame picture or explosive ingintion, as its condensing you cant see the flame pic so i would suggest an anaylizer reading be taken. Yep your right the instilation isnt correct but with just .9 mb down my betting will be corgi will do bugger all and try and smooth over the situation with all concerned. Its not the end of the world and when you get the extra .9 mb you wont notice the difference. Its just a shame as its not to difficult to do the job correctly in the first place. I would say 30-40 % of the appliances i service are hovering just below the correct wp.

    I would also say if a tee and a test nipple were fitted directly under the appliance you would find an increase in wp as a number of the zero govnor gas valves seem to have quite a resistance in the path the gas travels through.

    Sorry to say i have no faith in corgi or the acs qualification scheme just recently interviewed some chap who was fully gassed up actually think he had more qualifications than me, cv said 18 months ago he was delivering mail. Kinda says it all really

    good luck with corgi

  2. Captain Leaky

    Captain Leaky New Member

    Mainflow? Plumblocal? or Hart Heating?

    Ha ha!

    If it's one of the above I know who my money is on!
  3. Gordon S

    Gordon S Member

    None of those companies I promise and I am not going to reveal who it is until it is sorted.

    We have continued to use the boiler since Transco gave us an extra 2mb, so we assume we have 19mb to the boiler when no other appliances are running.

    We also assume we still have a 3mb working pressure loss on the run.

    CORGI will be made aware that the only reason the boiler is now getting 19mb is because of Transco.

    Incidentally, would this situation be detrimental to the longevity of the boiler. Is it like running a car on normal unleaded when the manufacturer says it must be run on Super Unleaded?
  4. Captain Leaky

    Captain Leaky New Member


    1st Class


    Nosey or what ;)
  5. chris73

    chris73 New Member

    If your getting 19mm at the boiler the corgi expert(ha)
    will say it`s fine how allowed 2 bar drop , Yes i`m still trying to find the paperwork to back that up , I do remember the conservation with the corgi man myself .

  6. Gordon S

    Gordon S Member

    Another quick question for you CORGI lot pls?

    During the commissioning of 'the boiler' late last year, the installer (apparently) identified a 0.75mbar leak on the gas fire and issued us a warning/advice notice and turned it off at the local isolation valve to the fire. (We asked the installer twice to fix the leak but they never bothered - hardly surprised really!). 12 months earlier, when we purchased the house, we had the place checked over by a CORGI engineer and he found no leaks at all.

    With all this aggro of low working pressure to the new boiler, I just wondered whether the installer (perhaps) decided we should not use the fire in case it caused even more loss of working pressure to the boiler? It also ties in with the fact they didn't try to fix it - despite being asked twice.

    As an experiment, I turned the valve back to 'on' by the fire (4 hours ago) and the gas meter reading has not moved at all..... not even a tiny tiny little bit. Would this confirm we actually don't have a leak?

    Finally, much of the original gas pipe between the meter and old boiler is still in place. It's all 22mm. Surely a decent installer would have identified that a convoluted 22mm run would never be adequate for this WD42CDi?

    Your comments pls, esp. in respect of the apparent leak.
  7. HOTDOG ø

    HOTDOG ø Active Member

    I'm no CORGI but even I know you cannot detect a leak by watching a meter. Turn it off again, if there is a leak, even a very small one it could be very dangerous. You need a manometer on the meter to test for leaks.
  8. Gordon S

    Gordon S Member

    To be fair, even the installer said it was a "safe leak" (if there is such a thing) and put on the advice note, "no smell of gas" and we also have a substantial air brick ventilating the room.

    Incidentally, who is CORGI registered who has answered this thread?

    PS I've not been watching the meter. I checked it at midday and just recently nearly 4 hours later and it has not move even a microscopic amount.
  9. bettyswallocks

    bettyswallocks New Member

    perhaps the installer does not have his ticket to work on gas fires.
  10. HOTDOG ø

    HOTDOG ø Active Member

    There is CORGI and there is CORGI - different tickets for different appliances basically.
  11. mantor

    mantor New Member

    I would also say if a tee and a test nipple were fitted directly under the appliance you would find an increase in wp as a number of the zero govnor gas valves seem to have quite a resistance in the path the gas travels through.

    I agree with that, said it on page 3
  12. chris73

    chris73 New Member


    It sounds like the installer did the right thing with the fire ,you are allowed a drop on a gas appliance if you cannot smell gas , he`s given you the warning notice and to fix it would have been an extra job to repair the leak , Watching the meter will not get you anywhere regarding the leak ,
    It`s about time you had another gasman round to check the work and maybe repair it and send the bill tothe first installers .

    corgi 208307
  13. Gordon S

    Gordon S Member

    Just took a call from CORGI. They are visiting on 8th May. Will keep you all informed.

    Presumably the installer is notified as well and will be expected to attend?

    Thanks for your guidance.
  14. Captain Leaky

    Captain Leaky New Member

    They are visiting on 8th May. Will keep you all informed.

    I trust it won't be a fudge but it usually is with CORGI:(
  15. Gordon S

    Gordon S Member

    Pinged back to top!
    CORGI inspector should be here in half an hour.
    Not sure if installer is going to turn up.
  16. HOTDOG ø

    HOTDOG ø Active Member

    keep us informed ;)
  17. Gordon S

    Gordon S Member

    The Corgi inspector has just left along with the boss of the installation company and one of his engineers. Suffice to say, the CORGI fella was a pleasure to deal with and acted very neutrally but firmly. The engineer was also chatty but the boss could not have been more offish about the whole thing. He even turned down a cup of tea twice despite being here for 1 1/2 hours.

    The inspector got them to check the working pressure loss was the 3mbar that I had reported, which indeed it was and the installer was told this was unacceptable, even though an appropriate working pressure was reaching the boiler. The boss tried to say this was "all OK", "no problem" etc as an appropriate working pressure was now reaching the boiler (thanks to a new regulator provided by Transco). The inspector had none of it and simply stated a maximum of 1mbar loss was the only acceptable situation.

    The inspector did the calcs and indicated the run should only give just over a 1mbar loss. They then established that between the gas connection point on the boiler and the inlet working pressure test point, there is a 1.5mbar loss inherent on the internal piping of the 42CDi. (The bit of pipe is no more than 200mm long!).

    The inspector is getting the company round next week to up the pipework sizing and has informed them they must lose 1.5mbar of the total 3mbar loss. The inspector is also taking the internal boiler pipework matter up with Worcester Bosch. Apparently the instructions are not clear.

    When the work is completed to satisfaction, then I will reveal the contractor's name. They have not done themselves any favours by having to be dragged here by CORGI.

    I heard mention of running some of the pipework in 35mm!

    Any questions?
  18. oliver1234

    oliver1234 New Member

    Glad your getting somewhere Gordon, some of these RGIs are worse than DIYers lol
  19. Water Systems

    Water Systems New Member

    35mm seems over the top. Long lengths in 28mm would be good enough.
  20. devil's advocate

    devil's advocate New Member

    Good stuff, Gordon. So nice to hear that a professional organisation has come out and acted, well, professionally.

    The Corgi boss on t'other hand...

    (I'd have thought, tho', that the narrow pipe in the W-B which is causing an additional 1.5mb drop is neither here nor there - surely the W-B is designed with this pipe in mind, so the actual pipe-run pressure drop should be measured at the end of the pipe, before the boiler.)

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