Radiator Valve Sizes

[AWJD]

My radiator came with the tail/unions already in place and that is what I was trying to connect a new valve to. What I was trying to understand is what are considered standard union thread sizes for these types of valve and why Screwfix do a 1" threaded connection to the union but proper plumbing merchants don't?

Fortunately, I've now got a replacement valve from Screwfix and so the problem is solved!

 

[rpm]

My radiator came with the tail/unions already in place and that is what I was trying to connect a new valve to. What I was trying to understand is what are considered standard union thread sizes for these types of valve and why Screwfix do a 1" threaded connection to the union but proper plumbing merchants don't?

Fortunately, I've now got a replacement valve from Screwfix and so the problem is solved!

Hurrah! :hurray: arty:
I think the merchant was messing with you tbh.

 

[PlumbBobBob]

it is called 3/4" not 1" that's why

 

[rpm]

it is called 3/4" not 1" that's why

Which makes BSP so confusing to the unexperienced.

 

[Stoney Ground]

My radiator came with the tail/unions already in place and that is what I was trying to connect a new valve to. What I was trying to understand is what are considered standard union thread sizes for these types of valve and why Screwfix do a 1" threaded connection to the union but proper plumbing merchants don't?

Fortunately, I've now got a replacement valve from Screwfix and so the problem is solved!

What was the screwfix part number in case one of us guys come up against the same problem.

 

[AWJD]

I bought part 36552 from Screwfix. As said, I took the original valve into the 2 x plumbing merchants and neither had a size that matched. I'm going back to Screwfix tomorrow to get another valve for the other end of the radiator without the drain.

 

[AWJD]

it is called 3/4" not 1" that's why

I was referring to the diameter of the tread which was 1". And yes, this is also referred to as a 3/4" BSP thread- and the plumbing merchants still didn't stock it!

 

[rpm]

I bought part 36552 from Screwfix. As said, I took the original valve into the 2 x plumbing merchants and neither had a size that matched. I'm going back to Screwfix tomorrow to get another valve for the other end of the radiator without the drain.

Glad you got it sorted in the end however left wondering exactly what words you used ie did you say 1" for the radiator in which case I can understand the response you got.

 

[AWJD]

I needed to sort out the issues with my radiator valves because this summer I will need to get all the valves changed (TRVs included this time) and didn't want any nasty surprises in terms unavailable parts. My final understanding is the following:

1. All my old radiators and modern radiators use tails which all have a 1/2 BSP male tapered threads going into the radiator.

2. Therefore, since replacement valves come with a tail, it should be possible, worst case, simply to replace the old tails (and valves) with the new tails (and valves).

3. The old standard for valves was to use a 3/4 BSP union connection ('O' ring or fibre washer seal) to the radiator tail.

4. The new standard for valves is to use a 15mm compression connector to the radiator tail.

5. Many plumber merchants don't appear to stock radiator valves with union connections any more - fortunately, other outlets, such as Screwfix do stock them still.

This has been a bit of a steep learning curve for me, not helped by not knowing what correct terminology to use at times! However, I got there in the end!