Broken Radiator valve

[diy-newby]

Last night I turned off the rad valve in preparation to remove the rad for decorating the room. Once I turned off the manual valve it started leaking. Basically, the valve itself has sheered off. I had to drain the entire CH system last night to stop the water.

Question is, is it possible to buy just the valve or do I need to buy the entire rad valve inc the housing?

If I want to replace the manual valve with a TRV, is it a direct replacement, or do I need to remove the tail from the rad?

Thanks

[John]

Perhaps best to take the complete valve into a Plumbers Merchants. For examples see:

there a makers name?

[diy-newby]

Thanks, had a look on screwfix earlier. They seem very cheap compared to B&Q, but others have said the B&Q ones are utter rubbish - what does that make screwfix ones then?

I may just replace the whole assembly with a TRV? Just not sure if I need to remove the rad tail first?

[Owain]

Probably the same as B&Q, but sold cheaply by mail order to the "trade" instead of being an impulse buy for people going into a B&Q shed for some fluffy cushions.

Owain

[Dave Plowman (News)]

It depends on the make of TRV you choose and the valve it's replacing. But bank on replacing it - it's not difficulty. You'll need the special tool, though (allen key) - anywhere that sells TRVs etc should have it.

[Roger Mills]

There are at least two different systems used for connecting a radiator tail to the valve. You may get away with using an old tail with a new valve if they use the same system - otherwise, you've no chance! One system uses a shouldered male conical outer end on the tail, in conjuction with a back-nut - and a corresponding female cone on the valve. The other system uses a conventional compression joint in the valve, and the tail is effectively a piece of 15mm plain pipe with a thread on one end to screw into the rad. [1]

The compression fitting approach means that the inlet and outlet of the valve are interchangeable so that - particularly with TRVs - you can mount the valve so that its gubbins are either horizontal or vertical (as long as it's also bi-directional).

[1] You can see the two types by going to the above Screwfix reference and scrolling down to the tails (adjustable in this case), where one is described as Union Type and the other as Compression Type.

[diy-newby]

Many thanks for this. I am going to buy the the following TRV from Screwfix, Quote No 64739. I think the tail on the picture looks like the one I have. Currently, nut on the tail screws onto the valve (Union type??)

[John Rumm]

Yup, that is a union type. Note just to add a little more confusion there are two different sizes of union fitting commonly used. The pegler one you have mentioned uses the smaller size. Hence it may be still be possible that you need to replace the tail on the rad to get it to match valve.

If you do need to replace the tail, this is not that difficult. The pegler one has a flat on the outside that enables it to be turned with a spanner. The other common type is larger and uses a large allen key type affair to turn it[1] - although for removal where you have no need to reuse the old tail a pair of mole grips would get it out. Just use plenty of PTFE tape on the new valve tail before screwing it firmly into the rad. There is an article here that shows replacement of a valve that may help:

[Roger Mills]

It's difficult to tell from the Screwfix picture which type it is. All the union type valves which I have seen have union nuts which are considerably bigger than the compression nut for the supply pipe. Both nuts look the same size in the picture - and a compression type looks just like that when assembled.

I know that John Rumm thinks it's a union type - but I'm not totally convinced!

It's not totally clear from the installation instructions

, which say that the 15mm valve can be used in either orientation - implying compression fittings both end, but I don't know about the 10mm variety. Maybe a call to Pegler would be a good idea?

[John Rumm]

Hmmm, you have got me thinking now... ;-)

I just had a look at my screwfix order history, and the ones I used were quote number 19052. AFAICT these look the same except have 15mm pipe connections.

The tail fitting worked like the normal cone type tail, in that the nut remained captive on the tail. Without actually going and dismantling one now however I can't remember whether the end of the tail was a flat mating surface or had a spigot on it that would simulate a pipe end with olive over. For the purposes of this discussion though, I am not sure it makes any difference. They are notable however for being a smaller connection than normal, which is why I commented on it before. They are also smaller tail connections than those used on the pegler lockshield valves, so you can't swap the valve from one side of the rad to the other so easily.

[Clint Sharp]

In message , diy-newby writes

Part of the B&Q group of companies IIRC?