In article , Bob Eager
writes
On Sat, 21 Jun 2014 13:25:38 +0100, fred wrote:

In article , Bob Eager
writes

A Johnson Coupling...

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.

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

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.
--
fred
it's a ba-na-na . . . .