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Discuss No less than 18 mb inlet point in the Gas Safe Register Forum - Public Forum area at

  1. scott_d

    scott_d Plumber GSR Top Contributor!!

    Are you the only gas safe person in the company?
  2. Inverness

    Inverness Plumber GSR

    There's one other guy and he said it's ok too but I prefer asking your advise. 3 weeks today I'm going out on my own!
  3. KingDoey

    KingDoey Plumber GSR

    Correct me if i am wrong chaps but is this not AR? The boiler clearly has undersized pipework? Worcester allow 2.5 mbar from meter to inlet on gasvalve.
  4. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Aslong as it doesn't adjust the figures out of spec they say it's fine down to 14.5 mbar
    • Agree Agree x 1
  5. firemant

    firemant Plumber GSR

    Unless you can find anything to the contrary, undersized pipework is only the old NCS. Unless it is proved to be affecting the safety of any appliance, in which case it is ID. So either poor combustion resulting in CO to a room, or burner outage on, say, a cooker ring, when the boiler kicks in
  6. Inverness

    Inverness Plumber GSR

    I'm getting confused now... if Worcester says 14.5 mb at the inlet and the gas meter working pressure 19mb. From meter and gas inlet valve is greater than 2.5 mb drop.
  7. AWheating

    AWheating Trusted Plumber GSR

    Think worcester say 16.5 mb. 19 at meter minus 1mb on pipe work minus 1.5 on gas line of appliance. 14.5 mb on sum ideals I believe.

    In this situation always test hob on low flame and turn hot water/ boiler on full rate.
    • Agree Agree x 1
    • Informative Informative x 1
  8. johnduffell

    johnduffell Member

    Good idea, would be worth testing the hob with 3 rings on high and one on min, just to be on the safe side.
  9. Inverness

    Inverness Plumber GSR

    I can't thank you guys enough for your helpful advise
  10. kasser

    kasser GSR

    To continue with this pipe-sizing thread, isn't it highly likely the pipework will be undersized if it is a 22 mm pipe from the meter feeding several appliances throughout the house?

    I've just come across a house with the meter at the front and the boiler and hob at the back and the 22 mm pipe at meter was undersized by my calculations and also after measuring the pressure drop.

    Another property I've seen was a meter at the front + 2 small fires + gas hob + gas oven + non-condensing boiler with a 22 mm pipe from the meter to feed all this. Kitchen & boiler were at the back. Thinking back now, this would have been severely undersized?

    Last e.g: meter in outhouse, hob + boiler on 3rd floor flat, 22 mm pipe from meter to feed this. So if pipework was undersized in the first e.g, it's most likely going to be severely undersized here?

    Yet you rarely see 28 mm pipe from the meter in houses.
  11. dween

    dween New Member

    16.5 on pretty much all worcesters
  12. kris

    kris Trusted Plumber GSR

    He's only got 4m of 22mm plus 4 bends so 6m of 22copper. Having 22mm copper gives you press absorb of 0.4mbar so absolutely fine for gas rate of 3.35m3 so you pressure drop must be @ gas valve / inlet .
    But just thinking if you've a hob then your missing hob output and tee piece etc.
    Inverness what's the total length of copper as Well as how many gas appliances etc
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