I have installed a new boiler - ( taking into account everything
posted on the news group :) )
The old boiler rating plate was 100,000 BTU, fed from 22mm pipe.
The new boiler 80,000 BTU, is fed in exactly the same way. ( except
small run of 15mm at the last 1/2 m )
The hob pressure now fluctuates when the boiler lights, whereas it
didn't with the old boiler. I can't think why.
The input gas pressure is well over 20mbar (minimum required by
boiler) The burner pressure is 13mbar ( as spec ). The boiler takes
the correct amount of gas ( from timed meter reading ).
The boiler is about 4m from the meter.
The hob is fed from a T down to 15mm over a run of about 12m. T is
about 1m from the boiler.
I cant obviously re-fit the old boiler and see whats going on. One
thought is that the old boiler simply never switched off and we never
Presumably the hob has no local regulation - I havent checked if
there's any pressure test points on it.