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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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central heating combi boiler
hi there i have just purchased a central heating kit from Band Q the usual 7 radiators plus combi boiler valves flue etc .
on the boiler it has the gas inlet at 15 mm, i have been told by a lay man that it has to be 22 mm to feed the gas i am not doing the gas side of things but was wondering if this is true to have 22mm does this have to go all the way back to the meter . any info would be appreciated |
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"Paul Barker" wrote in message ... pickled_magpie Wrote: hi there i have just purchased a central heating kit from Band Q the usual 7 radiators plus combi boiler valves flue etc . on the boiler it has the gas inlet at 15 mm, i have been told by a lay man that it has to be 22 mm to feed the gas i am not doing the gas side of things but was wondering if this is true to have 22mm does this have to go all the way back to the meter . any info would be appreciated The rule of thumb is 22mm pipe to within 1 metre of the combi, then use 15mm to connect up. This is purported to be a practical rule of thumb for the average combi. If you have a really powerful model I expect you might need to go to 28mm. It also depends on the length of gas pipe you are running, there is more to the rule-of-thumb than I have mentioned, in that you can only have up to a certain length of 22mm, and you have to take into account any right-angle copper fittings as subtracting a certain amount from the max allowed length etc. Can't remember what the specifics are, you'll have to google for it or look in the u.k.d-i-y archives. I can tell you my 28kW boiler is fed by 22mm pipe to within a metre of the inlet, that the 22mm pipe is about 20 feet long with 2 right angle joints ( gentle curves don't count ) and ISTR that that was within the allowed rule, and the pressure at the boiler measured OK when operational, so that was a good reality check. DYOR. Andy. |
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andrewpreece wrote:
The rule of thumb is 22mm pipe to within 1 metre of the combi, then use 15mm to connect up. This is purported to be a practical rule of thumb for the average combi. If you have a really powerful model I expect you might need to go to 28mm. It also depends on the length of gas pipe you are running, there is more to the rule-of-thumb than I have mentioned, in that you can only have up to a certain length of 22mm, and you have to take into account any right-angle copper fittings as subtracting a certain amount from the max allowed length etc. Can't remember what the specifics are, you'll have to google for it or Chapter and verse he- http://www.cda.org.uk/megab2/build/p...0Tube%20Sizing long with 2 right angle joints ( gentle curves don't count ) and ISTR that Depends on whay you mean by gentle... a "swept" bend does count, just less than an elbow (i.e. adds 0.3m rather than 0.5m to the effective length of the pipe for the purposes of calculation) -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
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On Mon, 24 Jan 2005 19:07:27 +0000, pickled_magpie wrote:
hi there i have just purchased a central heating kit from Band Q the usual 7 radiators plus combi boiler valves flue etc . on the boiler it has the gas inlet at 15 mm, i have been told by a lay man that it has to be 22 mm to feed the gas i am not doing the gas side of things but was wondering if this is true to have 22mm does this have to go all the way back to the meter . any info would be appreciated See the Gas Fitting FAQ. -- Ed Sirett - Property maintainer and registered gas fitter. The FAQ for uk.diy is at http://www.diyfaq.org.uk Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html |
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