Old Imperial Radiator Valve Replacement

[shaungr]

I've search on the internet for many hours but cannot find the solution I need.

I have got a very old radiator in my house that fell off the wall. I have managed to take it off completely but the valve that connects to the copper pipe is damaged and needs replacing. It is an old style on and the threads on it are about an inch in diameter.

I have taken out the tail pipe to the radiator using a very large allen key and the hole in the radiator is 3/4 inch. I have searched the internet for hours for a solution but cannot find a product to buy without replacing the whole radiator (but then there is the issue of imperial to metric sizes). I thought I might be able to buy a tail pipe connection that has a 3/4 thread on one side and 1/2 pipe on the other, but cannot find them. I also thought I would simply be able to buy a valve with the old connectors but I cannot seem to find one.

Can anyone help me with a solution?

Thanks

 

[oz-plumber]

Can you post a pic of the valve.
The pipe and the connection to the radiator.

You never know, someone may have one lying around

 

[steadyon]

1. The thread (female) inside the radiator is almost certainly 1/2" BSP. This is the standard thread used in the vast majority of radiators of any age, with very few exceptions. The inside diameter of a 1/2" BSP thread is 19.1 mm or 3/4"
2. The part you have taken out of the radiator is called a tail. New valves come with new tails.
3. Measure the diameter of the copper pipe, accurately, approximations are not good enough. It will most likely be 15 mm. If not it will probably be old 1/2" pipe, but the half inch refers to the inside bore. The outside diameter of 1/2" pipe is a around 15.1 to 15.2 mm.
4. The connection of the valve to the radiator tail can be one of two sorts:
4a. A compression fitting. The unthreaded end of the tail is 15 mm in diameter. The nut then the olive are slipped onto this and the nut tightened.
4b. A union fitting. The tail has a large outer end which is also threaded around a dished joint. They are relatively uncommon nowadays, but can be useful if there is little play in the pipes. Little play can make it difficult to get the valve(s) over the tail(s) to do up the compression nuts.
5. Make sure you get valves with the correct type of tails.
6. The tails themselves screw into the radiator, and will need a good few wraps of PTFE tape to seal. Start with 12 wraps. If the tail screw in too easily, remove, remove the PTFE, re-wrap with 15 turns and try again. Always wrap in the direction of screwing in, otherwise the action of screwing in unravels the PTFE.

 

[shaungr]

Thank you so much for your in depth reply. It has been causing me a world of pain. I will give everything you have suggested a try

 

[Deleted member 120897]

As oz plumber said, photo wouldn’t help us a little better.