"Ed Sirett" wrote


By the book it usually possible to correctly design the pipework. In
practice the pipework in _most_ houses and flats (that I come across)
drops more than 1 mBar between meter and appliances.

The installer can't usually take the risk to reuse undersized (but
functional) pipework because the monitoring and inspection
process has real teeth.

By the book the meter supplies gas at 19-23 (used to be 20-22) mbar.
The pipework should take no more than 1 mbar so leaving 18mbar + at the
appliances.

The W/B will insist on 18mbar minimum inlet working pressure in the
manual.
IIRC this is a forced premix burner so will not readily tolerate poor
inlet pressures.

In practice the meter will almost certainly be giving 22 to 20 mbar at the
outlet depending on the rate of gas flow. This means that you will almost
certainly get your 18 mbar even with the fire on at the boiler. So you
have a functional but irregular installation just almost like everyone
else.


Thanks for the concise, informative response Ed.
Of course, the onus will be on the installer to check all this, but I didn't
want to go too far down a blind alley with my planning process.

Phil