Specific Radiator Leak Problem

[mjm22]

A friend of mine (no, honest) had a leaking radiator valve. A work colleague of hers fitted a new valve but she still has a problem with it so I said I'd take a look.

The new valve is ok on the fit to the 15mm up-pipe (even though the existing olive was used) but there is a constant leak where it connects to the radiator.

On the radiator end there is a large brass knuckle like ball with an nut around it that screws onto the new valve (bit like a large version of an olive really). I have cleaned off the thread of the nut as best I could with a wire brush (It was very corroded) and access is difficult, applied PFTE tape and reconnected the radiator. Although the rate is reduced it still leaks from this connection. I repeated the dis-assembly, clean and re-assembly a couple of times but could get it no better.

I suspect that the thread of the nut on the radiator side may be damaged (she has said she has had a few problems with it over the years resulting in it being disconnected a few times and tightened many others). The leak seems to be coming through the thread side of the nut rather than the end which butts up against the knuckle.

Now I have committed to helping I feel I owe her to get it sorted so wonder what the next step would be.

Often the radiator connectors come away from the radiator (as they are normally shipped without them) so I am thinking that replacing this would do the trick. Though with this one there seems to be no immediately obvious way of unscrewing it. Do some of these connectors need some special tool to undo them from the radiator? Also can you buy the connectors from general plumbers merchants?

Any other ideas from anyone would be useful. Thanks in advance.

 

[JohnD]

I bet when your friend bought the new radiator valve it came in two parts, one of them being the part that goes into the radiator. Has she lost it?

This bit (the "tail") screws in, some of them have a square shank that you can get a spanner round, most of the old ones have a hexagonal throat inside that you fit a sort of big allen key into. You will be able to see this hex inside the rounded end of the tail. You will find these wrenches in the plumbing tools section. there are various other tools that will fit (sump plug spanner, hex keys or squares in a socket set, you might even be able to hire a set from a tool hire co in case the old one is a funny size). You clean out the old thread, and then fit the new part having wound PTFE tape round the thread, or smeared it with Boss White, Plumbers Mait or similar. I don't know if we have a picture of the tails being fitted, that would make it very clear. As the old tail is probably stuck in very firmly, you want someone to hold the rad while you unscrew it, so it doesn't come off the wall and damage the copper pipe at the other end.

BTW if you try to use an old tail and captive nut on a new valve, it is quite likely not to fit as it will be a different make and model, this is the most likely cause of the drip. Consider changing the valves at both ends while you're at it, taking off the old nut and olive from the copper pipe as well. Warning: If the pipes come up through a concrete floor and have no movement to them, you may have another problem if the new valves are not exactly the same length as the old.

 

[mjm22]

Yeah I guess she should have the tail part for the new valve, I will check and find out if she still has it.

It was how to get the old tail out that is really helpful, thanks. There is nowhere I could get a spanner on it (like mine at home) so I guess it must be the internal hex throat type.

I was surprised when I realised that the old olive was still on the up-pipe as I would have replaced this. However at that point I was torn between my original 'Yeah, I'll just come along, add some PTFE tape and tighten that valve up for you" and the horror of having to spend a lot more time and effort on it.

Thanks for the info, very helpful. I think that the most important thing I have learned is not to volunteer to help out with other people's plumbing troubles, just stick to my own.

 

[ChrisR]

The proper key isn't expensive http://www.plumbworld.co.uk/241-0000 (L shaped ones at the bottom)
and don't use plumbers mait (useless muck imho!) but Fernox LS-X or similar, which is a silicone type goo in a tube. It works well on rust old threads if you get it tight first with ptfe tape. Roughen the male threads and wind lots of tape on tight then force it in with your thumbnail.