WB 28I rsf low inlet pressure.

[Deleted member 32524]

Hello folks. P1 standing pressure 23mb drops to 15 when demand comes on (dhw) Tested meter gov standing 24mb drops to 20mb but maintains that. Gas line looks to not be too long a run but does drop to 15mm quite a bit from boiler.

I am thinking possibly blocked filter on GV or pipe. Can filter be cleaned easily?

Also GV does not modulate down when water reaches temp.

Any thoughts would be appreciated.

 

[TBServices]

I'd fit a test nipple before boiler to determine whether its boiler or pipework at fault.

 

[Deleted member 32524]

good idea!! I like that.

 

[Mike Jackson]

I wouldn't want much 15mm on the feed to a 28i. You'll need something like 2.6 cubic metres per hour and you'll get a 1 mbar drop from just over 3m of 15mm alone without taking into account any of the losses on the 22mm.

 

[mfgs]

Just sounds like undersized pipework. Are there any other gas appliances? Is combustion affected by the low inlet pressure? Can the max burner pressure at the appliance still be achieved?

 

[Deleted member 32524]

Burner pressure can not be reached. Combustion ratio is at 0.0002. CO2 low due to burner pressure. Gas pressure also seems not to modulate down when water reaches temp.

Gas hob. No visual difference to flame. notice a small drop again on p1 on boiler.

 

[Deleted member 32524]

Tested the pipework with a test nipple and the pipework tests the same as gas valve. so problem on pipework. ordinal installer has falsified documents to suit!!?? Thank you to all who answered.

 

[mfgs]

Original installer probably didn't care. Loads of boilers with gas supplies undersized out there.

 

[Pssst]

I reckon there is a good living in this..i.e upsizing internal installations to combis.

So many are fitted on undersized pipe and not achieving full output on HW. The issue is being exacerbated by more and more combis and higher output combis being fitted which is putting more strain on local distribution networks which in many areas are already running toward the lower end of the pressure scale.

 

[arran197]

Yes, in theory, but you'd have to have all the taps running at the same time. Usually on CH they only run at about 9 kw, so less than some old stuff anyway.

Good idea with the test point, I suppose it was fairly cheap & rules out the expensive gv. So are you just going to up size the 15mm or up size the 22mm too?

 

[Deleted member 32524]

Arron. yes upgraded off meter to 28 to 1st t and then to boiler in 22mm. Once I lifted floor boards it was a long run in 15mm to boiler and there was also a 5 burner hob and gas fire. I agree with PSST there is a living in under gassed pipework upgrades.

 

[gassafe]

Maybe there is a living off it! But the custards think we're just ripping them off when we say the pressure is too low, we need to upsize pipes at great expense!

The way they see it is there £500 worse off, and the boiler still seems to work the same as before!