Compression nut thread sizes.

[davidb08]

Hello everyone.
I live in Australia and will be visiting the UK this christmas. I have noticed that central heating motorised valves are much cheaper than they are in Australia and I am considering buying a few while I am visiting.

In Australia we use BSP thread sizes so there will be no compatibility issues with threaded fittings. However on ebay valves with compression fittings are much cheaper then threaded ones. Here we commonly use 1/2", 3/4" and 1" copper tube which are assigned nominal metric sizes of 15mm, 20mm and 25mm. I have checked pipe size tables and our tube sizes are clearly incompatible with your ones. On Australian compression fittings the compression nuts use the corresponding bsp thread, 15mm compression fittings are compatible with 15mm bsp threads.
Are your 22mm and 28mm compression nuts using bsp threads and if so is that common to all manufacturers?
Thanks
David

 

[Paul Barker]

Mid pos and s plan valves use a finer thread than our 22mm compression fittings (which in any case are not 3/4" bsp.

You can buy 3/4" olives which will allow your 3/4" pipe to fit our 22mm valves. these are slightly fatter than standard 22mm olives.

1" pipe we have changed to 28mm the 1 " version is larger outside diameter, and has to be redused with emery cloth/tape and lots of elbow grease. In this instance we solder a 1" by 22mm endfeed converter in. You will probably just have to use elbow grease.

15mm nuts for compression fittings are 1/2" bsp. your 1/2 " pipe should go in with brute force or again sand it down a little.