I would like to increase the size of my initial radiator pipe to 22mm; to
do this I have to replace the ancient fitting on my H/W cylinder, and I'm a
There is what looks like a 28mm, more likely 1 1/8" stub comimg out of a
compression fitting that appears to be screwed in to the cylinder.
Could anyone tell me how to make this into a 22mm stub that I can plumb
away from; I guess I'll need to replace whatever fitting screws into the
tank, but I don't want to undo things I can't do up again !
Or will I need a new cylinder..... next year?
I'd be grateful for any help
Thanks for answering, Christian - I think the pipe stub is more likely to
be 1" from its age, but it looks bigger than that to me, (I can only see
about 1/2" of it)
And isn't 28mm considerably bigger than 1"? So are they compatible at all?
Could I just use a new olive?
Or the compression fitting that holds the stub seems to screw into the
cylinder, like a radiator fitting - would that have to be replaced, if so
I don't really know what fittings to even look for, but all my 7 (now) rads
are being driven through 1 15mm (1/2"?) pipe and it would be fairly simple
to improve if I can change the tank fitting.
Or is there a source of knowledge - I've tried the faqs and googled, but
not got any answers on this.
On Wed, 20 Aug 2003 18:29:41 +0000 (UTC), mike ring
You could try the Copper Development Association. I believe that
their web site has documents with tables of actual outside diameters.
You would either need a vernier caliper or perhaps a piece of thread
run round the pipe (then divide by pi) to get an accurate dimension.
Some of the imperial and metric sizes are fairly close.
In some cases you can transition with fittings, or different olives.
If your cylinder is of an age where the pipework was still imperial,
it may be nearing the end of its useful life, so if you are going to
do surgery, a backup plan would be prudent. This is not a job to
start after lunch on a Sunday......
To email, substitute .nospam with .gl
There's probably little point replacing the cylinder connection with more
than 15mm pipe. This is because if the cylinder is old enough for imperial
connections, the heating coil will be so low spec that it couldn't use the
additional heat transfer provided by the 22mm pipe. The reason the
connections are so large is because decades ago, installations were done
using gravity circulation of the water, which requires large unobstructed
passages. With a fully pumped system, 15mm is all you need. When you finally
replace the cylinder, you can then upgrade to 22mm, which may actually be
beneficial with a modern rapid recovery cylinder.
I'd be really surprised if the coil conection was anything other than 1"
The fitting that connects these usually have a brass back nut holding a
copper cone coupling into the coil pipe. The fitting then is a 28mm or
22mm socket suitable for soldering in a pipe or reducing fitting.
Ed Sirett - Property maintainer and registered gas fitter.
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