How does this adjustable radiator vlave tail work? All aspects of plumbing questions and answers, help, tips and information

[nitro23456]

Before I buy can someone advise me on how this works:

http://www.awin1.com/pclick.php?p=22508 ... 071&m=1228

Does the nut with the washer shown, screw into the actual radiator (well the threaded part, and the nut is used to tighten it in)? and does the straight bit of pipe then need an olive and compression nut to hold it onto the valve thread of the actual valve it connects to at the other end?

Any advice welcome

[plumbbob]

I have used these before.

The 1/2" flange with the rubber seal screws is the male fitteng that screws into the radiator. The tail has to be fitted with an olive and fits into the valve assy.

The flange has a integral rubber seal and is free to slide anywhere along the length of the tail - hence adjustable.

Trouble is I have had these weep after fitting, and if they are fitted to a pressurised system, the tail is always forced out to it's full extension so I wouldn't really call them adjustable.

Hope this helps.

[Steve the gas]

Hi,
You are bang on -yes.

[nitro23456]

Thanks for your replies.

How do I know if I need the tail above, or this one?:

http://www.screwfix.com/sfd/i/cat/00/p1054000_l.jpg

It will fit between the rad and a TRV and/or between the rad and the lockshield on my application - a 600mm wide rad replacing a 650mm one.

[thedoctor]

They seem to be the same fitting but the last one you posted (imnage only) already has the compression nut and olive in place. See the DIY Doctor projects section to understand more about copper compression joints.

[nitro23456]

I was just under the impression that the nut is 'part of' the rad and not the valve. I have bought a new 600mm rad to replace a knackered 650mm one and was expecting when undoing the 650mm one, for the nut that connects to the TRV, and likewise the lockshield, to be part of the rad.

Its just the new rad hasnt come with anything (no tails at all) and so now I am slightly confused. Unless all new rads come with no tails nowadays and you have to buy them...... in my case ones that also make up the 50mm gap.

I just need this clarifying before I undo it - I know how compression joints work, I have done bathrooms and showers.

The two images show two different products from screwfix. I dont understand why they sell one without the nut.

[thedoctor]

The second link you posted is only an image, can you post the link to the actual product. Both products in fact and we can check it with Screwfix for you. We are pretty sure they are the same product but its better to check.

[nitro23456]

I cannot find the second one on the screwfix website but its in their catalogue.

I presuming the difference is the union nut. What is a union nut and how does it differ from a compression join?

The radiator I am replacing has a TRV on the flow which looks like a compression join and the lockshield on the return has a bigger nut that I am presuming is a union nut. Question as above. Radiator virgin here.

[thedoctor]

Weve had a good look round and it seems the union type is no longer available so the compression type is the one to go for.

[plumbbob]

The difference between the two are the first 1/2 male thread screws directly into the radiator and the other free end is just like a piece of pipe so needs a 15mm nut and olive to join it. This one would normally connect to the side of a 15mm TRV.

The second screws into a radiator the same but has a 3/4" flange at the other end that would normally connect to a lockshield or a standard type valve.

[nitro23456]

cheers plumbob - that is the answer I was looking for!

thanks everyone for your help.