In article ,
Mike Armstrong writes:
Hi all,

I'm fitting my new boiler this weekend.

In order for the gas supply pipework to be sufficiently sized I am
replacing the final section of 15mm with 22mm.

The 22mm pipe runs under the concrete floor, through a swept bend
vertically up the wall to about 500mm from the floor where it is
reduced by a soldered 22-15 reducing connector to 15mm pipe. it
continues from here to the boiler.

The original installer has hacked a channel in the plasterboard
dry-lining and the pipe is set into this channel with a few mm
clearance to the blockwork wall behind.

This is all going on behind by kitchen units and I have created an
access hole to get at the joint.

I would normally cut the pipe and use a 22mm connector to extend the
22mm pipework, however access is extremely difficult. There is little
or no flex in the pipe to use my pipe splitter and the fact that it is
recessed behind the plasterboard makes using a hacksaw pretty
impossible.

I am wondering whether it would be easier to apply heat to the
reducing connector to 'un-make' the joint. The question is how hard
is it to clean up the 'un-made' end in preparation for the new 22mm
straight-through connector?

Redoing a joint like this which was done OK originally is not difficult.
You don't have to clean the pipe end up, just make sure the pipe end is
tinned all the way round (i.e. that it was a good joint originally).
You might not be able to push the coupler over the solder. In this case,
you will have to heat the pipe end in order to push the cleaned/fluxed
coupler on, and then heat the joint as normal until solder flows and add
a little more to make up for that lost in the reducer.

Redoing a joint when the original was not OK is harder, and would require
the pipe end to be cleaned up (and a new fitting as it's generally not
worth cleaning up an old one which failed to solder correctly in the
first place).

Once cleaned up would another soldered joint be necessary?
Compression would be easier!

Not allowed for gas in an inaccessible or confined space.
Are you sure you are competent to do the gas side?
Don't forget to do a soundness test before and after (so you know if
you've introduced a leak, and/or if there was originally a leak which
you need to go and find).

--
Andrew Gabriel