Discussion in 'Plumbers' Talk' started by Harriet Davies, Jan 12, 2018 at 4:28 PM.
Thanks for your advice, I have contacted the original installer and coming to inspect next week
If the pressure is 24 milli bars (mb) at the meter and 13 at the boiler, then the pressure drop is 11 mb. The pressure drop is not allowed to be more than 1 mb at any working appliance. However:
a. 24 mb is high for pressure at the meter. The regulator is meant to keep it in the range 19 to 21 mb although it has been known to be a bit higher.
b. What needs to be measured is working pressure at the meter and working pressure at the boiler with the boiler running full blast. The difference between pressure at the boiler and pressure at the meter should not be more than 1 mb. If it is more, then the pipe is under-sized or there is an obstruction.
c. Working pressure at the boiler should be between 15 and 23 mb measured at the test point. Can't remember, but I think Vaillant's pressure at test point is usually a few mb less than if the pressure were actually measured at the gas pipe as it enters the boiler.
d. It is possible for the gas meter regulator to be faulty. Be suspicious if the standing pressure reading fluctuates. It can be caused by water in the mains, but can also indicate a faulty regulator.
Performance readings were fine when installed
The meter has been changed, 18 months ago - could this be the reason?
Should i call British GAs to check the meter regulator?
The Gas Engineers on here should be able to offer better advice...when they come along.
Do you have the paperwork for the boiler, and has the the benchmark check at the back been filled in?
What are the recorded values for gas pressure at the meter and boiler when it was commissioned?
I take it this fault hasn't been happening since it was installed ?
13 is to low for that boiler according to their website, they say 15 minimum and 23 max.
This is from their (Valiant) web site.
Natural gas (G20)
Minimum pressure at reference test point in mbar 15
Minimum pressure at reference test point in mbar
Separate names with a comma.