I have a house built in the 70's Sometime between then and 1980 it had central heating fitted. I came to change a radiator. the connections on the pipes say 15mm but they dont fit standard 15mm fittings, looking at the connections they seem to have a different thread pitch. Any experienced plumbers out there who can help? Will I just have to drain system and replace these fittings?
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When is a 15mm thread not a 15mm thread
- Thread starter boothstownbopb
- Start date
The 15mm refers to the outside diam of the pipe, not to the size of the threads.
I found some years ago, when I removed some 15mm couplings the thread on the coupling and the compression nut were slightly differrent from standard.
The diameter was the same but the pitch was different.
I think there was one extra thread over an inch, making it a finer thread.
It's not clear which thread you refer to, or what the problem is?
If your replacing a radiator the threaded holes in both the old and new radiator would be standard 1/2 pipe (1/2in meaning bore diam not thread diam), so all you would need to do is transfer the tails from the old radiator to the new one and use the existing valves.
If your also changing the valves, then you would have to drain down and if the thread is different then you would have to replace the compression nut and to do that the existing olives would also have to be removed.
I found some years ago, when I removed some 15mm couplings the thread on the coupling and the compression nut were slightly differrent from standard.
The diameter was the same but the pitch was different.
I think there was one extra thread over an inch, making it a finer thread.
It's not clear which thread you refer to, or what the problem is?
If your replacing a radiator the threaded holes in both the old and new radiator would be standard 1/2 pipe (1/2in meaning bore diam not thread diam), so all you would need to do is transfer the tails from the old radiator to the new one and use the existing valves.
If your also changing the valves, then you would have to drain down and if the thread is different then you would have to replace the compression nut and to do that the existing olives would also have to be removed.
Just about all - if not all - 15mm compression threads - including Conex - is 1/2" BSPP thread.
All 22mm and above are b'stard threads.
Conex and Prestex used to do adaptors for their 22mm threads to 3/4" BSPP thread.
Many moons ago Prestex did do their own thread for 1/2"/15mm - and I do mean maaaaaaannnny moons. Might even have been pre metrification.
It's been 1/2" BSPP for as long as I can remember. (Which is about 2 weeks.
)Much metrification commenced in 1970 and the coinage was February 1971.
I think the 1/2" to 15 mm and the 3/4" to 22 mm pipe changes were 1970 too!
Tony
That's when I started in the game. For a few years we carried both imperial and metric ranges of all copper fittings.
Then there was the leaded to potable solder changeover for solder ring fittings where we carried both YL (leaded) and YP (potable) Yorkshire fittings.
The good old days.
Counter boys don't always have it cushy. There is no thread size specified within the BS and BS EN standards for compression fitting.
You should not therefore assume that the threads are BSPP without manufacture reference. They might be the same TPI, but the thread depth, radius and major diameter might all be different.
Without any manufacturer's reference, the only way of assuring compatibility is to use the original nut supplied with the fitting, and a blanking piece.
You should not therefore assume that the threads are BSPP without manufacture reference. They might be the same TPI, but the thread depth, radius and major diameter might all be different.
Without any manufacturer's reference, the only way of assuring compatibility is to use the original nut supplied with the fitting, and a blanking piece.
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