Purging gas pipes?

Harry Stottle

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Mar 15, 2009, 9:23:30 AM3/15/09

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I have just had a combi boiler installed and now need to remove a gas fire.
The gas fire supply will be blanked off at the main gas pipe running through
the house, not at the fire itself, and there is a gas cooker also fed from a
branch off this main pipe. After the feed to the gas fire has been blanked
off, I can easily purge the air from the pipe to the gas cooker, but this
will leave about a 3 metre feed to the boiler unpurged, and I don't really
want to disturb any boiler connections. My question is, will the boiler self
purge itself through its starting process, or is there anything else I
should be aware of before restarting the boiler?

A.Lee

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Mar 15, 2009, 10:28:44 AM3/15/09

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Harry Stottle <thiswo...@nowhere.uk.co> wrote:

I worried about this too when I fitted my boiler, but it didnt seem to
be a problem at all, the boiler lit far faster than I woudl have
expected - the pipe is maybe 4 metres long from meter to boiler.

The gas hob on the other hand took far longer than expected.
I had done neither before, so had no prior knowledge of how long they
take.
Alan.

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To reply by e-mail, change the ' + ' to 'plus'.

Ed Sirett

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Mar 15, 2009, 3:56:59 PM3/15/09

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If your just capping a gas fire then you won't get any air into the rest
of the pipe work.

--
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

TheScullster

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Mar 16, 2009, 4:36:28 AM3/16/09

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"Ed Sirett" wrote

>
> If your just capping a gas fire then you won't get any air into the rest
> of the pipe work.
>

Are you assuming that he will use a compression blank rather than a soldered
cap here?

Phil

Harry Stottle

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Mar 16, 2009, 4:40:27 AM3/16/09

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"A.Lee" <alan@darkroom.+.com> wrote in message
news:1iwmirz.ebepcp1bz0i9mN%alan@darkroom.+.com...

> Harry Stottle <thiswo...@nowhere.uk.co> wrote:
>
>> I have just had a combi boiler installed and now need to remove a gas
>> fire.
>> The gas fire supply will be blanked off at the main gas pipe running
>> through
>> the house, not at the fire itself, and there is a gas cooker also fed
>> from a
>> branch off this main pipe. After the feed to the gas fire has been
>> blanked
>> off, I can easily purge the air from the pipe to the gas cooker, but this
>> will leave about a 3 metre feed to the boiler unpurged, and I don't
>> really
>> want to disturb any boiler connections. My question is, will the boiler
>> self
>> purge itself through its starting process, or is there anything else I
>> should be aware of before restarting the boiler?
>
> I worried about this too when I fitted my boiler, but it didnt seem to
> be a problem at all, the boiler lit far faster than I woudl have
> expected - the pipe is maybe 4 metres long from meter to boiler.
>

Thanks for the replies, and even more reassuring, the lack of warnings :-)

Ed Sirett

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Mar 16, 2009, 1:40:58 PM3/16/09

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If the joint remains accessible and it's done right it makes no
difference to me.

A.Lee

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Mar 16, 2009, 5:15:43 PM3/16/09

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Ed Sirett <e...@makewrite.demon.co.uk> wrote:

> On Mon, 16 Mar 2009 08:36:28 +0000, TheScullster wrote:
>
> > "Ed Sirett" wrote
> >>
> >> If your just capping a gas fire then you won't get any air into the
> >> rest of the pipe work.
> >>
> > Are you assuming that he will use a compression blank rather than a
> > soldered cap here?
> >
> >
> If the joint remains accessible and it's done right it makes no
> difference to me.

Does the gas burn off when you try to solder a joint without first
purging it out?
or would you always try to purge out the gas before capping a pipe?
Ta

Harry Stottle

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Mar 16, 2009, 3:22:10 PM3/16/09

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"Ed Sirett" <e...@makewrite.demon.co.uk> wrote in message
news:Kawvl.187986$Dz4.1...@newsfe20.ams2...

> On Mon, 16 Mar 2009 08:36:28 +0000, TheScullster wrote:
>
>> "Ed Sirett" wrote
>>>
>>> If your just capping a gas fire then you won't get any air into the
>>> rest of the pipe work.
>>>
>> Are you assuming that he will use a compression blank rather than a
>> soldered cap here?
>>
>>
> If the joint remains accessible and it's done right it makes no
> difference to me.
>

Soldered cap, now done and tested with no problems, thanks again.

Ed Sirett

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Mar 17, 2009, 3:13:50 PM3/17/09

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You obviously have to turn off the gas. 8-).

You have put the cap on the end and it is already more or less gas tight
with the flux. The soldering process will not set light to gas which has
little or no oxygen in it and which is inside the pipe.

However you should not solder any gas pipes within in 2m of the meter.
Disconnecting the meter etc is a more advanced topic.