Joining galvanised to copper

[BillP]

Anyone have any ideas to join galvanised steel pipe to copper on a central heating system (other than threading the pipe). Philmac UTC 15-21 does the join the data says it's only cold water rated

[Bob Eager]

Over 30 years ago I had exactly the same problem. The local (knowledgeable) plumbers' merchant sold me the solution, as as far as I know it's still in there (we moved, but know the people who bought the house as we only moved 50 yards).

A Johnson Coupling...

[BillP]

Over 30 years ago I had exactly the same problem. The local (knowledgeable) plumbers' merchant sold me the solution, as as far as I know it's still in there (we moved, but know the people who bought the house as we only moved 50 yards).

A Johnson Coupling...

[fred]

Interesting things but I'm struggling to find full information.

Are they really ok to use on heating? The closest data I can find is for larger diameter stuff (Viking Johnson Megafit couplings - 2" min) and while there is a nitrile based seal version for use to 100degC, it does say, "Not suitable for fluctuating temperature, e.g. heating systems" on that range.

Searching through Primofit branded variants eventually leads to a datasheet but it's brief to say the least and does not mention temperature or cycling.

[Bob Eager]

I think ours was a nitrile seal (but it was a long time ago) so I may just have been in blissful ignorance...

[fred]

I suppose they might be worried about wear on the seal elements from repeated expansion/contraction cycles but as you say, if it has worked for you/them all this time then it can't be all that bad.

Not cheap though.

Thanks for pointing them out.

[Andrew Gabriel]

When I've needed to do this, I've taken the iron out back the the nearest coupling, and then used a BSP to compression fitting.