Altering central heating

[DIYer]

I need to move a couple of radiators. For neatness, I would prefer to use end feed or solder ring fittings on the pipe alterations but how do you expel all the water to ensure a good joint?

Thanks

[charles]

with difficulty

[Dave Liquorice]

Well you have to drain down and provided there is no water arriving(*) at the joints due to gate valves not shutting off properly a bit of damp inside the pipe very quickly evaporates when you get the blow lamp close.

(*) "No" as in none at all. Even a drip a minute is enough to stop a successful soldered joint being formed. It's also worth making sure that the air/steam from damp pipe has somewhere to expand to the open air, otherwise the pressure build up will blow the solder out of the joint

[Dave Plowman (News)]

If you have a reasonably powerful vacuum cleaner that will blow as well as suck, blow through the pipes for a while - obviously only if you have a drain point at the lowest part open elsewhere. Works for me. I actually use a turbine compressor for a LPHV spray set.

[fred]

In article , Dave Plowman (News) writes

If you just want to clear a branch then a car tyre compressor will do at a pinch, just close off the rads you don't want to empty and watch the pressure. It'll take a few minutes but it does work.

[Andrew Mawson]

[The Natural Philosopher]

This is true

I generally find that horizontal sections can be bent down to darin then up long enough to solder before the drip arrives.

freeze spray works allegedly. as well.

>

[robgraham]

(snip)

+1 to those. I had to add isolators and drain downs to a CH branch and used the freezer spray. I found the pipe stayed frozen for quite a bit longer than the tin said it would.

Rob

[Bash]

In extremis you can ram some crusty bread up the pipe using the tang of a file. This will stop the odd drip enough to get the solder to melt. The bread will flush out easily when the system is refilled. This has saved my bacon several times when that drip just won't stop.

[Andrew Gabriel]

I designed/installed my CH with all pipes sloping towards one of two pairs of drain points.

[ARWadsworth]

Yes, but you are not a pro:-)

[Dave Plowman (News)]

Very difficult here as all pipes are under the floors etc. And they're just as likely to slope the wrong way. ;-)

[Andrew Gabriel]

Mine are all under the floors too. I didn't want the not-quite-horizontal runs to be visible.

[ARWadsworth]

You just need more drain points:-)

When I did last CH system I had to accept that there was going to be a U shaped section under a steel girder that could not have drain off points.