Advice on gas pipe run

[andrewstokes87]

Hi,
Sorry if this has been mentioned before but I am knew to this forum. I am currently working as a sub contractor and I have been asked if there is a limit on the size of the gas run I can install as the person I am working for is not gas safe registered but he believes that I can only install upto a certain length as the volume of gas will be too large for my domestic tickets, but I was under the impression that I can install upto 35mm pipe and a limit on the length was unaware to me aslong as we got the correct pressure on the outlet. Basically the job is 5 new flats and a shop and the gas run to each flat will be in 28 mm and will basically need to travel a fair way to the outlet. Please can someone clarify if my intrepretation is correct or if my boss is correct please can someone tell me where I can find the information which relates to the max distance.

Thanks
Andrew

 

[GQuigley67]

there is a limit on the volume of the gas, then your tightness test and purging changes and requires commercial ticket.

 

[kirkgas]

the max criteria for a domestic engineer is 0.035m3 for the total IV (Installation Volume) incl all pipes and meter,
Total IV = IV of meter + (IV of all pipes +10% for the fittings)

U16 has 0.025m3
U6 has 0.008m3
E6 has 0.0024m3

35mm copper has 0.00084m3 per 1m
28mm copper has 0.00054m3 per 1m
22mm copper has 0.00032m3 per 1m
15mm copper has 0.00014m3 per 1m

so to work out max pipe length:
0.035-your meter IV, then divide answer by pipe value above this will tell you roughly how many meters of pipe you can use, (remember to work in the 10% for fittings)

U16 and approx 10m of 35mm pipe
E6 and approx 54m of 28mm pipe
E6 and approx 90m of 22mm pipe

obviously a real job will have a mixture of different pipe sizes, but im not doing all your work for you haha
PS remember if you end up with pipe runs at the max end you prob wont get enough m3/hr delived to an appliance, check tables in BS6891 for flow per meter length

 

[andrewstokes87]

Ok, thanks, do you know the maximum length I can run a 28mm gas pipe then? I have only ever done it on domestic houses so this is something I need to find out ( which is usually 6 metres max), any help would be much apreciated.

 

[andrewstokes87]

kirkgas thanks, ignore my last post lol, basically there has been a designer do all the drawaings for the building, the person I am sub contracted to just wants me to find out wether I can to the gas runs on my domestic ticket or if he needs to get someone else in.

 

[kirkgas]

kirkgas thanks, ignore my last post lol, basically there has been a designer do all the drawaings for the building, the person I am sub contracted to just wants me to find out wether I can to the gas runs on my domestic ticket or if he needs to get someone else in.

you will get a rough max length from my ramblings, but remember to confirm gas flow so you need to know HI of the appliance (multiply max HI x 0.094 to give gas flow, then check tables to see max length of pipe you will get this flow from)
eg 28kw boiler needs 28x0.094=2.63m3/hr, then check table to see that you can use up to 30m of 28mm pipe or up to 20m of 22mm

 

[andrewstokes87]

Yes I understand its all coming back to me now, thanks.