Radiator valve size

11 May 2015
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United Kingdom
Hi all. This is my first post on the website so please do not start shouting if I make some mistakes. I have read some amazing posts and I think I can help in some instances as well but I am sure you will be able to help a novice DIYer as I am.

I am buying a house now and planning to replace all radiators with aluminium ones. I am buying them from Germany but I need some help. Is the tail on the following valve 1/2"? I know the pipe it fits on is 15mm but the side that connects to the radiator confuses me. http://m.screwfix.com/p/drayton-rt212-white-chrome-trv-15mm-angled-l-s/53581 I am not trying to advertise but this is the type of valve I will want. The radiator comes with 1" 'holes' and 1' to 1/2" bushes and just wondered whether the valve would fit. Cannot get hold of my plumber unfortunately.
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First you need to understand what is meant by 1/2 bsp and other bsp sizes..It all starts with steel steam and water pipe,before copper came on the scene.
1/2 inch pipe has a bore of 1/2 in. The outside diam being about 0.8 in so when threaded with a standard pipe thread it's much bigger than 1/2in and this causes some confusion.
My understanding is that radiators have a threaded hole usually 1/2in bsp.
No doubt some could have a larger size.
Into this threaded hole, a radiator tail is fitted.
The tail will be threaded to match the radiator at one end.
The other end will depend on the valve.
It would appear the valve you intend to fit is 15mm so your tails will be 15mm diam at the opposite end and a olive will make a compression joint to the valve.
If the threaded hole in your radiator is too large, then that's where reducer would be used
Why do some posters start with "don't shout at me if I make mistakes"
Believe it or not we don't expect you to understand plumbing terminology,
just like we probably wouldn't understand if we asked a question about your job. Don't worry there's no such thing as a daft question ;)
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Thank you very much for your replies. Helped a lot.

I don't know why some users start with saying this but I know why I wanted to mention this. I am glad you do not think questions can be daft but I wish all people on forums think like that. I am currently discussing on 5 forums and you would be surprised how many people sometimes say "ohhh that's silly, how can you ask this" (I have to say it never happened to me but I can imagine how that feels for the people who asked the question/s initially). Anyway, I am very happy to see that people on this forum have a brain and use it. I am sure it will be a pleasure to ask questions and also answer questions where possible.

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