How do I know if there's a 20mm incoming gas main?

[AWheating]

I was talking to a nat grid engineer the other day and he said the min they have to supply is something like 16mb!

This is correct as they can allow as low as 16mb at "peak demand". What they tend to fail to tell you is that this peak time is only supposed to be something like 5% of the day. So unless it's early morning or tea time they can't really argue this, although some engineers will use this figure to avoid doing anything for you.

 

[AssuredHeating]

Went back there today, I now have 19mbar working pressure on 38kw full rate. So all is finally good. Thier pipe work from the meter to the boiler was terrible though......cocks.