BSP sized lockshield

[alangla]

I think I’m going crazy. Unblocked a section of my heating system at the weekend, but when I was checking the rogue radiator the lockshield was seized. Attempting to free it off resulted in the brass tab on the top snapping off. Fine thinks I, I’ll replace it, I’m sure I’ve done it before. So far I’ve tried 3 different lockshields, Drayton 15mm, Flomasta 10mm and Made4Trade 10mm, none fit. The pipe connection seems to be an old style speedfit type elbow with a captive nut on it, but the nut is too big to fit the 10mm valves and too small for the 15. That tends to suggest it’s a 12mm or 1/2 inch, measuring the bust valve with a ruler seems to confirm this. I can’t find imperial size lockshields anywhere though! System is only about 25 years old, so surely the parts should be available. What am I doing wrong?

[richhead]

alangla said:

I think I m going crazy. Unblocked a section of my heating system at the weekend, but when I was checking the rogue radiator the lockshield was seized. Attempting to free it off resulted in the brass tab on the top snapping off. Fine thinks I, I ll replace it, I m sure I ve done it before. So far I ve tried 3 different lockshields, Drayton 15mm, Flomasta 10mm and Made4Trade 10mm, none fit. The pipe connection seems to be an old style speedfit type elbow with a captive nut on it, but the nut is too big to fit the 10mm valves and too small for the 15. That tends to suggest it s a 12mm or 1/2 inch, measuring the bust valve with a ruler seems to confirm this. I can t find imperial size lockshields anywhere though! System is only about 25 years old, so surely the parts should be available. What am I doing wrong?

Im sure ive got 1/2 inch lockshields from screwfix before.

[.:ian:.]

Probably easier to just replace the bit that goes into the radiator as well, then it will fit. Though it may also be longer or shorter so hopefully theres slack in the pipe too

[ARH]

Show us some pics of what's is not fitting. 1/2 inch pipe is 15mm pipe, or certainly close enough to make no difference, 1/2 inch is the bore size 15mm is the external size. At least as far as I know i could be wrong.

[alangla]

I honestly can’t find them! Looked through Screwfix, Toolstation and spent about 15 minutes knelt on the floor of the local B&Q last night (should probably have tried a church, might have been more successful). The big problem is that the search function on the various apps finds the BSP outlet, but it’s the pipe connection I need in an imperial size.
I found 1 item in City Plumbing that looks to be imperial at both ends, but surely there must be more than that out there.

[alangla]

ARH said:

Show us some pics of what's is not fitting. 1/2 inch pipe is 15mm pipe, or certainly close enough to make no difference, 1/2 inch is the bore size 15mm is the external size. At least as far as I know i could be wrong.

System has been refilled with the broken lockshield back in place to get the hot water running so I can’t photo it dismantled, but I’ll post some pics of what I have in a couple of hours.

[ARH]

Its a bit confusing as the bit that screws into the radiator is a 1/2 inch thread, and the bit the feed pipe goes into is 15mm or 10mm if small bore pipework. Imperial pipework and threads are classified by the bore size, so a 1/2 inch thread is nearly 3/4 inch diameter or so. Pipe is now measured by outside diameter, Don't even think about BSP, BSPT, NPT or any one of the other specs. It's all very confusing.

As far as I am aware the tails on rads have not changed for as long as I have known. It must be nearly 50 years ago I first helped my Dad fit a rad.

Disclaimer, I am not a plumber, but I have done plenty of plumbing at home and whilst developing various machines.

[.:ian:.]

When I added TRVs to all the rads I had to replace the tails on that side as the threaded nuts on the old (1990s) tails were too large for the valves I bought.