On 02/12/2019 14:44, wrote:
On Monday, December 2, 2019 at 2:15:51 PM UTC,
wrote:
Plan was to use 22mm blanking nuts on the solar in/out, and then
chunk a compression nut and solve on a piece of pipe on every other
fitting. Googling shows the existence of cylinder unions e.g
https://www.bes.co.uk/22-mm-x-1in-fe...-end-feed-6794
- but I can't work out if these are simply a time saving device to
make it easier to align everything for soldering, or if there is
anything special about the connection.


Ignore that bit, I can see the difference now - 1" is not 22mm. But
I'm assuming that in general a 22mm compression nut is actually a
BSPP 3/4"?

Cylinders IME often have either a male threaded connection, onto which
some kind of coupling similar to that in your link can be screwed on. Or
often, the cylinder connection is just a protrusion of stainless /
copper pipe of appropriate size, onto which they expect the installer to
fix a compression fitting. If yours was previously installed and was of
the second type, you may now have a compression fitting with the
original outer compression nut and olive missing. That fitting might be
3/4" and not BSP. The outer diameter of 3/4" pipe is slightly smaller
than 22mm. That usually means that with some effort you can get a 22mm
compression fitting to mate with 3/4" pipe, but you can't get 22mm pipe
into a 3/4" compression fitting.

A photo of what you have would help...


--
Cheers,

John.

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