Advice on gas usage, incorrect billing and checking please

molerat

eclareb wrote: »

HI

Im sensing from the OMG that this is not good.
Thanks for the info, Ive tried to read it, but its not making a lot of sense to me. Does the table show the max lengths of pipe that should be used?

Yes. Use Table 1, a bit easier to understand. On the left hand side it shows the tube size, you have said it is 22mm. Look along that row to find the gas usage of your boiler, jalexa has quoted 3.25, find the closest figures, which are 3.6 - 2.8, and go up the columns giving a max pipe length of 15 - 20 metres. This is in a straight line, below it gives what to add to your actual length for each bend and tee fitting.

molerat

eclareb wrote: »

Hi, yes its in the back of the book.
States:
system has been flushed: yes
cleaner was used: x400
inhibitor was used : x 100

Central Heating measure and record:
Gas Rate: no entry
Burner Operating pressure: no entry
Central Heating Flow Temp: 68 dec C
Central Heating Return Temp: 55 deg C

Domestic Hot water Mode
Gas Rate: 2.76m3/hr

CO2 9.7%
CO 29 ppm
CO/CO2 Ratio: 0.0003

Does this suggest incompetency in installation - that the gas rate and operating pressure have either been missed or left off intentionally?

The DHW test gives a figure from Table 1 on the borderline of 20m straight line 22mm pipe so possibly why the CH figure has been left off. Guard that piece of paper well.

eclareb

molerat wrote: »

Yes. On the left hand side it shows the tube size, you have said it is 22mm. Look along that row to find the gas usage of your boiler, jalexa has quoted 3.25, find the closest figures, which are 3.6 - 2.8, and go up the columns giving a max pipe length of 15 - 20 metres. This is in a straight line, below it gives what to add to your actual length for each bend and tee fitting.

Thanks for that. Can see now why the 28mm pipe is needed.

From where the meter is, at best its a minimum of 8 bends, but without knowing exactly where the pipe runs, its not easy to say exactly.

Needless to say, no call from the boiler company yet.

jalexa

eclareb wrote: »

From where the meter is, at best its a minimum of 8 bends, but without knowing exactly where the pipe runs, its not easy to say exactly.

Needless to say, no call from the boiler company yet.

Another thing for completeness. Given the very low supply pressure reported by the WB engineer, it is not impossible that the regulator is defective.

But please treat that as a red herring until the gas pipework design adequacy has been demonstrated. That is a matter of fact which cannot be fudged.

penrhyn

The initial problem was excessive gas consumption.
Surely the inadequate gas supply to the boiler would decrease the overall amount of gas used or am I wrong?

jalexa

penrhyn wrote: »

The initial problem was excessive gas consumption.
Surely the inadequate gas supply to the boiler would decrease the overall amount of gas used or am I wrong?

My requested "rate-test" returned a DHW input rating of approx 26kW (assuming an accurate meter:D). I speculated about that number being a tad low for a 30CDi but I think the DHW gas-rate recorded on the Benchmark may explain that. So I don't think the boiler is getting less gas than its setting, the problem is that having taken its required gas the pressure ends up low which would be a problem for other burners, particularly non-FSD hobs.

But you are right, there seems to be multiple, not well understood problems, not excluding user unfamiliarity.

eclareb

jalexa wrote: »

My requested "rate-test" returned a DHW input rating of approx 26kW (assuming an accurate meter:D). I speculated about that number being a tad low for a 30CDi but I think the DHW gas-rate recorded on the Benchmark may explain that. So I don't think the boiler is getting less gas than its setting, the problem is that having taken its required gas the pressure ends up low which would be a problem for other burners, particularly non-FSD hobs.

Can you please clarify for me, does the above mean that the 5 is left pressure once the boiler has taken the gas it needs to function? So its running ok on what it needs?

But you are right, there seems to be multiple, not well understood problems, not excluding user unfamiliarity.

I dont have any other gas appliances so the hob prob isnt a risk.

Yep you are right about the user unfammiliarity!

Spoke to Gas Safe technical dept who initially said that the information i was giving to him meant nothing to him!!! I tried to explain that what ever units the WB engineer was measuring in, he said the boiler was reading 5 and should be 24.( Have to say, I found it a little obstructive to say the least. )
He eventually said that if they come out and inspect it and find it to be incorrect they would contact the company and make them put it right. He did verify that it should all have been checked by them at installation. So at least Im armed with that info when the intaller comes out in the morning - which he has agreed to do, although the subject of meeting the cost has yet to be discussed.

(oh yes and he also said that when they do fit the correct pipe the boiler will use MORE gas, so not solving the inital problem.

But then when the boiler gas correct supply, it should be working more efficiently?
Would it not having sufficient supply mean it would burn for longer before getting up to temp? or never getting up to temp? so in real terms cost more?

eclareb

jalexa wrote: »

My requested "rate-test" returned a DHW input rating of approx 26kW (assuming an accurate meter:D). I speculated about that number being a tad low for a 30CDi but I think the DHW gas-rate recorded on the Benchmark may explain that. So I don't think the boiler is getting less gas than its setting, the problem is that having taken its required gas the pressure ends up low which would be a problem for other burners, particularly non-FSD hobs.

/QUOTE]

Can you please clarify for me, does the above mean that the 5 is left pressure once the boiler has taken the gas it needs to function? If thats the case, should the WB guy have turned it off?

macman

Yes, because it's inherently unsafe and he is legally obliged to disconnect. If he does not, then he is potentially liable for the consequences should a device go out, and a leak and explosion occur.
It's the equivalent of wiring an electrical circuit in a gauge of cable that cannot take the maximum likely load.

jalexa

eclareb wrote: »

I tried to explain that what ever units the WB engineer was measuring in, he said the boiler was reading 5 and should be 24.( Have to say, I found it a little obstructive to say the least. )

I don't totally understand the 24/5 numbers myself. The meter regulator output pressure should be about 20mbar and the maximum pressure drop 1 mbar at the boiler. BTW I stand to be corrected by practicing gas engineers. Dunno why they are all silent.

If the WB engineer is trying to say the pressure was 5mbar than that is very low. Whether 24m + bends of 22mm would result in 5mbar I can't say. But it is not necessary to say because 24m + bends of 22mm pipe is not adequate from a design perspective for the rated output of a 30CDi.

I'm slightly worried there might be hidden sections of 15mm.

And the meter regulator being faulty can't be excluded. Again, academic until after the pipework design is proved adequate.

Sorry your lack of hob makes no difference for the reasons given by macman.