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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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#1
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Gas pipe fitting Q's
A couple of questions regarding extending gas pipework:
1) It is illegal to run gas pipe in a cavity wall because of the possibility of gas build-up, does this mean it is preferable where I have the choice to run gas pipe along a wall rather than under floorboards? 2) How do I clear the existing pipe of gas before soldering the new pipe on? The pipe comes down from the meter, under the floor (presumably horizontally but I've got no way of telling) and then up in a cupboard which is where I will be making the join. So I would imagine most gas will escape once I open up the old pipe - but with things like this it is best to make sure! Should I open up the test nipple at the meter to aid dispersion? I don't have any gas analysis devices. N.B. I am fully aware of the need to purge air from the new installation. Thanks Pete. |
#2
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Gas pipe fitting Q's
"PM" wrote in message ... A couple of questions regarding extending gas pipework: 1) It is illegal to run gas pipe in a cavity wall because of the possibility of gas build-up, does this mean it is preferable where I have the choice to run gas pipe along a wall rather than under floorboards? Under boards is fine as it is ventilated on the ground floor and enough space under on suspended floors too. 2) How do I clear the existing pipe of gas before soldering the new pipe on? The pipe comes down from the meter, under the floor (presumably horizontally but I've got no way of telling) and then up in a cupboard which is where I will be making the join. So I would imagine most gas will escape once I open up the old pipe - but with things like this it is best to make sure! Should I open up the test nipple at the meter to aid dispersion? I don't have any gas analysis devices. N.B. I am fully aware of the need to purge air from the new installation. Turn off the gas and undo the meter outlet union. Between the meter horn and the union insert a lid from say a flux tin. This prevents any flashbacks down the pipe from blowing the meter. There is no need to get rid of the gas in a small copper gas pipe. In larger systems the gas has to be pumped from the pipe via a flame trap hose to outside. In reality a flame trap hose is needed on an installation when purging too. Few are ever used on domestic systems. |
#3
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Gas pipe fitting Q's
On Wed, 14 Jun 2006 13:23:40 +0100, PM wrote:
A couple of questions regarding extending gas pipework: 1) It is illegal to run gas pipe in a cavity wall because of the possibility of gas build-up, does this mean it is preferable where I have the choice to run gas pipe along a wall rather than under floorboards? 2) How do I clear the existing pipe of gas before soldering the new pipe on? The pipe comes down from the meter, under the floor (presumably horizontally but I've got no way of telling) and then up in a cupboard which is where I will be making the join. So I would imagine most gas will escape once I open up the old pipe - but with things like this it is best to make sure! Should I open up the test nipple at the meter to aid dispersion? I don't have any gas analysis devices. N.B. I am fully aware of the need to purge air from the new installation. As always if you need to ask you probably shouldn't be doing it... 1) Through cavity is fine but there are extra rules. See BS 6891 2) No need to purge gas from the pipes. You will need to seal the meter outlet if working within 2m of the meter. The gas can only burn if comes into contact with air. Even when unsoldering fittings the most you even get is a small flame which goes out in a few seconds. -- 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 Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards |
#4
Posted to uk.d-i-y
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Gas pipe fitting Q's
"Ed Sirett" wrote in message news On Wed, 14 Jun 2006 13:23:40 +0100, PM wrote: A couple of questions regarding extending gas pipework: 1) It is illegal to run gas pipe in a cavity wall because of the possibility of gas build-up, does this mean it is preferable where I have the choice to run gas pipe along a wall rather than under floorboards? 2) How do I clear the existing pipe of gas before soldering the new pipe on? The pipe comes down from the meter, under the floor (presumably horizontally but I've got no way of telling) and then up in a cupboard which is where I will be making the join. So I would imagine most gas will escape once I open up the old pipe - but with things like this it is best to make sure! Should I open up the test nipple at the meter to aid dispersion? I don't have any gas analysis devices. N.B. I am fully aware of the need to purge air from the new installation. As always if you need to ask you probably shouldn't be doing it... 1) Through cavity is fine but there are extra rules. See BS 6891 2) No need to purge gas from the pipes. You will need to seal the meter outlet if working within 2m of the meter. The gas can only burn if comes into contact with air. Even when unsoldering fittings the most you even get is a small flame which goes out in a few seconds. I have seen a flash dow 6 metres of pipe and a boom as the guts of the meter blew. |
#5
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Gas pipe fitting Q's
In message ews.net,
Doctor Drivel writes N.B. I am fully aware of the need to purge air from the new installation. As always if you need to ask you probably shouldn't be doing it... 1) Through cavity is fine but there are extra rules. See BS 6891 2) No need to purge gas from the pipes. You will need to seal the meter outlet if working within 2m of the meter. The gas can only burn if comes into contact with air. Even when unsoldering fittings the most you even get is a small flame which goes out in a few seconds. I have seen a flash dow 6 metres of pipe and a boom as the guts of the meter blew. I bet you have -- geoff |
#6
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Gas pipe fitting Q's
"raden" wrote in message ... In message ews.net, Doctor Drivel writes N.B. I am fully aware of the need to purge air from the new installation. As always if you need to ask you probably shouldn't be doing it... 1) Through cavity is fine but there are extra rules. See BS 6891 2) No need to purge gas from the pipes. You will need to seal the meter outlet if working within 2m of the meter. The gas can only burn if comes into contact with air. Even when unsoldering fittings the most you even get is a small flame which goes out in a few seconds. I have seen a flash dow 6 metres of pipe and a boom as the guts of the meter blew. I bet you have Maxie, I did. Boom, then meter not working. I have also seen one blow as a blowtorch was passed over a meter horn and the meter was disconnected. Maxie, I have seen many things. |
#7
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Gas pipe fitting Q's
AIUI it is sometimes safer to ignite the gas in the pipe deliberately after
disconnecion from the meter. An aquaintance of mine was blanking off a connection when the gas in the pipe ignited and blew the cap across the room. Phil |
#8
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Gas pipe fitting Q's
The message ews.net
from "Doctor Drivel" contains these words: Maxie, I have seen many things. Attack ships on fire off the shoulder of Orion? -- Skipweasel Pay no attention to that man behind the curtain. |
#9
Posted to uk.d-i-y
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Gas pipe fitting Q's
On Wed, 14 Jun 2006 22:16:24 +0100, Doctor Drivel wrote:
"Ed Sirett" wrote in message news On Wed, 14 Jun 2006 13:23:40 +0100, PM wrote: A couple of questions regarding extending gas pipework: 1) It is illegal to run gas pipe in a cavity wall because of the possibility of gas build-up, does this mean it is preferable where I have the choice to run gas pipe along a wall rather than under floorboards? 2) How do I clear the existing pipe of gas before soldering the new pipe on? The pipe comes down from the meter, under the floor (presumably horizontally but I've got no way of telling) and then up in a cupboard which is where I will be making the join. So I would imagine most gas will escape once I open up the old pipe - but with things like this it is best to make sure! Should I open up the test nipple at the meter to aid dispersion? I don't have any gas analysis devices. N.B. I am fully aware of the need to purge air from the new installation. As always if you need to ask you probably shouldn't be doing it... 1) Through cavity is fine but there are extra rules. See BS 6891 2) No need to purge gas from the pipes. You will need to seal the meter outlet if working within 2m of the meter. The gas can only burn if comes into contact with air. Even when unsoldering fittings the most you even get is a small flame which goes out in a few seconds. I have seen a flash dow 6 metres of pipe and a boom as the guts of the meter blew. What was the pipe diameter? Pure gas can't go 'boom' as it's concentration is way above the UEL. -- 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 Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards |
#10
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Gas pipe fitting Q's
"Ed Sirett" wrote in message news As always if you need to ask you probably shouldn't be doing it... First time for everything! I've read up a lot (including your FAQs) but there are some areas such as this where I'm not sure. My mind has been made up to DIY mainly because of the incompetence and obvious dishonesty of the "tradesmen" I have had round for gas work in the past, and for quoting for a new boiler. 1) Through cavity is fine but there are extra rules. See BS 6891 Through cavity yes, along length of cavity no because of gas build-up. So is it better to avoid under floorboards if possible or is it fine as Drivel says? I have the choice of running the pipe in the corner of the ceiling (unsightly) or under floorboards. 2) No need to purge gas from the pipes. You will need to seal the meter outlet if working within 2m of the meter. The gas can only burn if comes into contact with air. Even when unsoldering fittings the most you even get is a small flame which goes out in a few seconds. Thanks! |
#11
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Gas pipe fitting Q's
On Thu, 15 Jun 2006 08:49:44 +0100, PM wrote:
"Ed Sirett" wrote in message news 1) Through cavity is fine but there are extra rules. See BS 6891 Through cavity yes, along length of cavity no because of gas build-up. So is it better to avoid under floorboards if possible or is it fine as Drivel says? I have the choice of running the pipe in the corner of the ceiling (unsightly) or under floorboards. A link to BS 6891 can be found under 'gas fitting standards' below. If the under floor space is ventilated then there is no problem, this is common practice. It is quite awkward to get the pipes under the floor in these circumstances. Compression joints should not be used. -- 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 Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards |
#12
Posted to uk.d-i-y
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Gas pipe fitting Q's
"Ed Sirett" wrote in message news On Wed, 14 Jun 2006 13:23:40 +0100, PM wrote: A couple of questions regarding extending gas pipework: 1) It is illegal to run gas pipe in a cavity wall because of the possibility of gas build-up, does this mean it is preferable where I have the choice to run gas pipe along a wall rather than under floorboards? 2) How do I clear the existing pipe of gas before soldering the new pipe on? The pipe comes down from the meter, under the floor (presumably horizontally but I've got no way of telling) and then up in a cupboard which is where I will be making the join. So I would imagine most gas will escape once I open up the old pipe - but with things like this it is best to make sure! Should I open up the test nipple at the meter to aid dispersion? I don't have any gas analysis devices. N.B. I am fully aware of the need to purge air from the new installation. As always if you need to ask you probably shouldn't be doing it... 1) Through cavity is fine but there are extra rules. See BS 6891 2) No need to purge gas from the pipes. You will need to seal the meter outlet if working within 2m of the meter. The gas can only burn if comes into contact with air. Even when unsoldering fittings the most you even get is a small flame which goes out in a few seconds. When I cut the old pipe ready to solder the new pipe on, won't the gas mix with air at that point? The old pipe is vertical up a wall and I will be cutting it about a foot from the floor. Won't the gas will rise out of the existing pipe so could be in the 5-15% concentration either above the pipe, or within the pipe? |
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