Soldering 28mm fitting

[Rick Hughes]

Have to replace a failed expansion vessel on boiler primary loop.

So at same time making use of drain down to fit in a 28 x 28 x 1/2" BSP tee to which I'll fit a 4" pressure gauge.

I have done 28mm fittings before, but these have just been the end feed type .. same thickness as pipe ... this Tee is obvioulsy a fair chunk of metal, any different technique needed, or just have cleaned & fluxed pipes in cleaned ends of fitting and use torch on fitting only. Feed in solder once fitting hot enough to melt it.

This will be with a hand-held lpg blowtorch, not a professional plumbers torch.

[newshound]

In my experience it is usually easier to get an even temperature in the more massive fitting (obviously the torch needs to be big enough but a standard "aerosol can" type torch should be OK). You can test when the fitting is getting up to temperature by touching the solder to the body. And even though the main heat goes on the fitting I would still "flick" the flame over the pipes intermittently prior to actually applying solder.

[BruceB]

You might just do it with an ordinary blowtorch if good access, but I found when I had a load to do that I had to go up to the mixed gas to get enough heat. Do not know what it stands for but screwfix call mit MAP/Pro.

[newshound]

If you are assembling the parts "loose" then just provide something insulating and heat-reflective to stop heat leaking away; rockwool, vermiculite, or even domestic bricks.

[Rick Hughes]

Nope ... will be cutting into the vertical drop to Thermal store. I'll be using an asbestos reflector mat so that will help.

[Roger Mills]

Soldering 28mm ain't easy without lots of practice, and you only really get one chance.

Have you considered compression fittings - or even copper pushfit - instead?

[Andrew Gabriel]

I've done 28mm with cheap blowlamps OK. It only got difficult when the disposable cylinder was running low. It hadn't run out, but I didn't realise until I swapped it for a new one what a difference that made.

For brass fittings, I start by playing the flame full pelt on that as it will take a while to heat, and you want to get it up to temperature as quickly as possible before all the flux has gone. Then play the blowlamp on each pipe-end for a moment before soldering; the brass will stay hot - indeed beware of not moving anything for a while as it will take a while for the solder to solidify and premature movement could easily break the joint.

Another option would be to use an end-feed 28-28-15 with a 15mm pipe stub connected to a 1/2" BSP fitting. Could use the stub to orientate the guage with bottom entry.

[Dave Liquorice]

Same here, one trick is to move the relatively small flame around the fitting and pipe as much as possible otherwise the back of the fitting/pipe will take an age to get get hot enough.

[Rick Hughes]

I'll have an asbestos reflector mat curled around pipe so should help that ... job on cards for tomorrow. One thing is .. once I cut into the 28mm ... I have to get the joint done :-)

[Dave Liquorice]

They aren't really reflector mats just summat to stop the heat getting where it's not wanted. I hope it isn't asbestos either...

Moving the flame around the pipe and fitting is by far the best way of heating it up. With the tip of the inner cone just clear of the metal.

[Rick Hughes]

as follow up ... this went fine .... once prepped actual soldering start to finish under 2 minutes. Handheld blowlamp was fine.

Had a bitch of a job on the Expansion vessel though .... which I thought would be easy.

Removed old one ... new one (same make & part No.) turns out to be different size ... so could not use existing bracket. Plus if fouled cupboard door.

They have these insane brackets that need to be clamped onto the vessel before you fix to the wall ... but you can't fix to wall when attached to vessel as it blocks screw holes. Plus the bracket clamp screw are angled towards the wall ... so you can't tighten them once fitted to wall .... Hours of fun !

Then I filled system ... and would you believe it only one to leak was the male thread stud onto top of pressure vessel into the filling valve ... the only one I could not fix by tightening ... had to take damn thing off and apply more PTFE tape.

Simply job stretched to 4 hrs.