As I started this one about the W-B clip running, I ought to say something.
It appears that the pressure tapping point on the old boiler was at the burner. The guy doesn’t say where the point is, and the boiler isn’t identified, so if that is the case, I missed it (along with other posters, it seems). In any case, there doesn’t seem much point in taking readings on the old boiler as it’s coming out. The tapping point on the new boiler also isn’t mentioned, and can’t be seen on the clip. My guess is it’s at the boiler inlet, or maybe at the gas valve inlet, but not at the burner, whether or not it’s a zero-pressure gas valve, so 16.5mb isn’t a surprise. Nor is the difference from the old boiler figures. And we still don’t know where the 21.5mb mentioned in the clip comes from. There’s no data on pressure at the meter, and the 21.5mb might be at zero flow.
Also unless there’s big increase in boiler output, hence gas flow, it’s common sense to connect the new boiler using the existing gas pipe and check pressures to see if it’s OK, rather than install a bigger pipe just in case. Installers don’t need W-B to tell them that.
So I still think the clip is rubbish, and there appears to be some agreement.
