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?
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.
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.
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.
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.
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.
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