On 08/11/2019 18:10, John Rumm wrote:
On 08/11/2019 17:02, newshound wrote:
On 08/11/2019 12:47, John Rumm wrote:
On 08/11/2019 10:16, wrote:
On Friday, November 8, 2019 at 10:12:17 AM UTC,
wrote:
Is the connection between a radiator tail and the actual valve any
sort of standard?

This bit is a stupid question isn't it. It must be either 3/4 or 1/2"
because why would anyone bother setting up for anything else.

Well its not as daft as it sounds...

The tail socket into the rad is almost always 1/2" BSP female.
However the other end of the tail varies. Traditionally it was a cone
fitting retained by a 3/4" BSP nut that was captive on the tail.
However more commonly these days the tail is often just a length of
15 mm pipe, and the valve has a 15mm compression fitting that then
connects to that (ultimately leaving a 1/2" BSP not captive on the
tail, but retained by the olive rather than the cone fitting).


Definitely do not assume standard threads, you may have to remove the
fitting that goes into the radiator, rather than just swapping the
"valve" bit. This needs a big allen key and they are sometimes very
tight from corrosion. In my experience you can usually get away with the

Some of the modern ones seem to use a couple of flats on the stem to
allow them to be turned with a spanner, rather than having the hex inner
profile... Personally I prefer the hex versions.

slightly different dimensions by using the flexibility of the copper
pipes, provided they are not too constrained close to the radiator.
One of those jobs that usually takes longer than expected, IME.

Yup, although sometimes you get lucky...



The original rads in my 1976-built house have 3/4 inch female
BSP socket, and the valves were fitted by a Gorilla using
boss white and hemp.