Vailliant ecotec pro 28 low gas rate

[sammathias]

Alright guys, just a quick one. Fitted a vailliant ecotec pro 28 today and upon commissioning the gas rate was slightly lower than 10% of the nominal, which baffled me because ive probably fitted 20 of these boilers and they have all been within range.
All of my other checks where fine so i was just how it was so low?

meter working pressure 21mb
working pressure at boiler 20mb
gas rate was 2.70m3/h at full rate which is slightly lower than 10%
All FGA readings where accepible 87ppm 9.1% with casing removed 0.0010 etc etc.

Pipework run is literally 5m of 28m pipe with 1m of 22m.

If anyone could give me a reasonable answer i would be grateful.

cheers

 

[GrahamM]

What is your working for this?
Is the Pro 28 badge output not 28.0kw on DHW? If so I am working it out as well within the 10%.
You defo getting tap flow on full?
What type meter?

 

[Scott_D]

How did you gas rate it?
Service mode with a tap open?

 

[sammathias]

Cheers for the quick responee as usual! Boiler was in full rate mode p.01 with two taps open.
Well in the M.I it states nomial rate of 3.10m3/h.
+5% being 3.25 and 10% being 2.79. My measurement fell slightly below the 10% and not sure how?
Used a gas rate app at first then double checked by doing normal calculator which gave the same reading...its a G4 meter. Done the rate 4 times.

 

[Scott_D]

Best to ring Vaillant. If they say it's not acceptable they will have to send out an engineer

 

[JAH HEATING]

Are you putting the boiler into P01?

 

[sammathias]

yes pal, have a read above..all info is there.

 

[IND_Nick]

Have you checked the inlet pressure at gas valve while on full. Could be meter is slow, I spoke to a NG lad who said they can slow down when they get older so don't record quite as accurate as before.
If gas pressure is 20 and you are getting correct hot water rise in wouldn't worry just note it on
Benchmark.