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Jul 18, 2016
22
1
3
Southend-on-Sea
Member Type
General Plumber
Hi,
writing up my last report for my gas portfolio and have come up against something i can't work out whilst doing the gas rate figures!!
Data plate shows Hot water pnw 34kw and qnw 34.7kw (hi)
manual shows gas rate norm level 3.78m3/h minimum 3.4m3/h maximum 3.97m3/h
If i fudge a gas rate level to 3.78m3/h that is equivelant to 40.67kw gross which is 36.64nett.
They don't match up? are the data plate figures nett?
I even called valiant, they were useless............
Reason i am asking is that I don't want to mess up my portfolio by making a mistake! my gas rate came out at 3.42m3/h which is too close in my opinion to the MI docs minimum allowance....
Any ideas?
 
What was the inlet pressure at the boiler?

What did Vaillant say when you spoke to them?
 
Vaillant weren't of much use, only asked CO2 levels from a safety point of view... He said i could email them but they will take ages to reply.. LOL. I just wanted to try and understand the levels in MI's against data plate on the boiler......
Inlet pressure was ok 19.5mb
 
just to be clear, my issue isn't really with my personal gas rate obtained. Its with Vaillants quoted figures!
Ive attached the data plate........ and as stated the norm gas rate is 3.78m3/h +5% -10%
what would you say the max input is from the data plate and is that a nett figure?

IMG_5844.jpg
 
I'm not sure what the issue is? You've gas rated it and it's within the MI range. If the MI allows you that range then it's correct. TBH i've never had a Vaillant over read that much anyway, they're usually slightly under the nom.
 
Installer level, codes in the book. Then p.01 with tap on full. After 10 minutes start p.01 again then take gas rate.
 
Ok.....
Install was with official Vaillant installer..... Gas rate obtained by putting boiler into installer modes and running hot water!!
my point as stated..........
vaillant instructions show 3.78m3/h as norm with tolerance of +5%/-10%
boiler data plate (as shown in picture) shows max heat input pnw 34kw and qnw 34.7kw.
gas rate is a formula..... if i work out a gas rate of 3.78m3/h gross this gives you a kw level of 40.67 gross or 36.64nett NOW.... if you look at data plate. that means that the norm expected for this boiler is 34kw or 34.7kw (data plate)
the point i am making is, i don't think the vaillant figures can tally up correctly...
I know my gas rate obtained is within guidelines, i just don't get the manufacturers levels.....
 
Didn’t think you could put the hot water on in P1 on the new Vaillant’s? As it is just like running a tap normally?
 
Tbh I always find Vaillants to be on the low side. They can be next to the meter, with correct pressures etc. and still be low!
 

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