Pressure at gas meter

[Alex (YMG)]

Dear all,

I had Transco round today as when I measured the operating pressure (38kw boiler & gas hob on full) at the test point on the meter (a G4 meter) I was getting a reading of between 16-17mbar.

He adjusted the governor so that I now get 21mbar operating pressure (lovely!). He stated however, that I was wrong when I said that I thought the specification was 21mbar +/- 1mbar, and that they were only obligated to supply 19mbar (I take that as meaning 20mbar +/- 1mbar).

My reason for asking is that Glow-worm state a minimum inlet pressure of

20mbar on the 38Cxi, so allowing for a 1mbar permissible drop in the internal supply pipework - if Transco were operating at their lowest 'obligated pressure', even with no pressure drop in my internal pipework, I wouldn't be able to meet this requirement.

Or have I completely misunderstood something??

Many thanks

Alex

[Paul Barker]

Only Transco can tell you what they work to. I had heard it wa different to our (corgi) guidelines.

Just a small point you are referring to operating pressure when wha you are talking about is working pressure.

In the event that working pressure is not exactly what the manufacture require what to do depends on whether the appliance is workin satisfactorily, it's a judgement you can't make. In the evnt you hav obtained the necessary raising of your govenor by Transco so in you case the situation is resolved

-- Paul Barker

[Ed Sirett]

AIUI he is partly wrong and partly right. The meter should be set to 21 mBar. However the governor is not perfect and a small variation over the range of gas rates (from just one hob ring, say, through to all appliances on) is acceptable so 21 +/- 1 mBar

With a maximum drop of 1 MBar for pipe work this means that appliances will be delivered gas at 19-21 mBar. Some appliances will state that they can be supplied at less (eg. Keston and Vaillant boilers only require

18mBar and some gas fires are happy with 17mBar). An appliances that states it requires gas at 20 means 19-21.

In addition to this there are times and places where due to an inadequate supply or an incident (say involving a JCB) Transco can't supply at a pressure which proved for 20-22 mBar so in that case they are allowed as a temporary measure to go down to 15mBar. To compliment this all appliances are certified as safe (cf. effective) down to 14mBar (or presumably lower for those that specify 18 or 17.

[Alex (YMG)]

Dear Ed & Paul,

Thank you both for your replies - much appreciated.

Best wishes

Alex