Gas system question (Corgi types/ Home DIY people)
Discussion
We have had a boiler service just done and they have turned off our boiler.
It's a standard boiler, not a combi boiler.
Apparently there is a pressure drop greater than 1mbar from the meter to our boiler. He says this is due to the pipework from the meter being 15mm instead of 22mm.
Now, if he said that the flow was not enough then that makes sense. But if we have a set pressure before the meter then surely fitting a larger bore pipe will only increase the differential pressure between pre meter and boiler?
Am I missing something obvious?
Dave!
It's a standard boiler, not a combi boiler.
Apparently there is a pressure drop greater than 1mbar from the meter to our boiler. He says this is due to the pipework from the meter being 15mm instead of 22mm.
Now, if he said that the flow was not enough then that makes sense. But if we have a set pressure before the meter then surely fitting a larger bore pipe will only increase the differential pressure between pre meter and boiler?
Am I missing something obvious?
Dave!
Its not BS but he hasn't explained it properly to you.
Basically, the standard for domestic supply states that "the pressure drop along the pipeline at periods of max. demand should be less than 1mbar." This is because there is a danger that if you use an undersized pipe, the pressure at the burner might be less than is required for complete combustion. I.e. carbon monoxide is produced. This = SUPERBAD!
Now, the longer the length of pipe you use, or the more 'T' pieces or elbows in the pipe run, the greater the pressure loss. The pressure loss is less with larger diameter pipe. As the price diff. between 22mm and 15mm is f
k all, I am surprised the main branch wasn't specced correctly in the first place.
You size the pipe by taking into account the max. demand required [i.e. boiler & oven on] and the pipe layout needed to supply those devices from the meter. The CORGI guy will have done this [or really knows from experience] and found 15mm to be insufficient. Oversizing is always good if you think you may need to add other branches in future or fit larger appliances.
Take a look at this document:
http://www.ukcopperboard.co.uk/literature/pdfs/Ins...
I used this to spec. and install the pipe run for my build. You can do the pipe run yourself which will save £££ but need the CORGI guy to connect and commission.
Does the pipe run through a solid floor or suspended? If its a solid floor you will be told a load of conflicting advice about how it should be installed. Most of this will be bks but I can advise you on this if required.
HTH. I used capitals and punctuation and everything
Basically, the standard for domestic supply states that "the pressure drop along the pipeline at periods of max. demand should be less than 1mbar." This is because there is a danger that if you use an undersized pipe, the pressure at the burner might be less than is required for complete combustion. I.e. carbon monoxide is produced. This = SUPERBAD!
Now, the longer the length of pipe you use, or the more 'T' pieces or elbows in the pipe run, the greater the pressure loss. The pressure loss is less with larger diameter pipe. As the price diff. between 22mm and 15mm is f
k all, I am surprised the main branch wasn't specced correctly in the first place. You size the pipe by taking into account the max. demand required [i.e. boiler & oven on] and the pipe layout needed to supply those devices from the meter. The CORGI guy will have done this [or really knows from experience] and found 15mm to be insufficient. Oversizing is always good if you think you may need to add other branches in future or fit larger appliances.
Take a look at this document:
http://www.ukcopperboard.co.uk/literature/pdfs/Ins...
I used this to spec. and install the pipe run for my build. You can do the pipe run yourself which will save £££ but need the CORGI guy to connect and commission.
Does the pipe run through a solid floor or suspended? If its a solid floor you will be told a load of conflicting advice about how it should be installed. Most of this will be b
ks but I can advise you on this if required. HTH. I used capitals and punctuation and everything
^ ^ ^ ^ ^
Just about sums it up.
The running pressure does indeed drop if that pipe twixt meter and appliance is undersized. It's important to realise that with 21mB available at the meter you need to do your utmost to avoid pressure drop.
Just as an aside to the info above. Many people choose to use leccy ovens..we test gas pressure at the boiler with 2 or three hob rings on. (and a gas fire on low if there is one)
Just about sums it up.
The running pressure does indeed drop if that pipe twixt meter and appliance is undersized. It's important to realise that with 21mB available at the meter you need to do your utmost to avoid pressure drop.
Just as an aside to the info above. Many people choose to use leccy ovens..we test gas pressure at the boiler with 2 or three hob rings on. (and a gas fire on low if there is one)
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