towel rad - leaking from bottom valve tail fixing

[Tom]

Hi All,

The instructions with this towel rad merely said use PTFE tape around the tread of the value tail when screwing this into the rad.

But I can't stop it leaking (slow drip) - it purely replies on the thread of the valve tail to keep it water tight - there is no flange for the tail to but up onto. The blanking plug and bleed valve at the top don't have this issue as they have rubber seals that sit between them and the rad itself. this isn't possible with the valve tails.

I've tried leaking compound - no luck, it still leaks - slowly drips actually.

Any suggestions as to what might solve this?

Thanks, Tom

[Toby]

You did put the PTFE tape around the thread before you screwed it into the radiator didn't you, not at the bottom, afterwards!?

If so, how many turns of PTFE did you wrap around the thread (approximately)?

Toby...

[Roger Mills]

These things are *meant* to seal on the threads, and usually do! The tail is slightly tapered, and should go tight at a certain point without needing a positive end stop - but you need the right amount of PTFE tape to ensure that this happens. I find that gas grade tape - which is slightly thicker - is far better than the standard stuff. Make sure you wrap the tape the *right* way round the tail, so that it isn't forced out when you screw the tail in. If all else fails, use liquid PTFE - but that shouldn't really be necessary.

[Tom]

Thanks for all the replies - I'll give a thicker version of the PTFE tape a try when I get some.

The towel rad is new and splitting should not the case... I hope.

The tread of the valve tail I think is probably parallel rather than tapered, however I'll take a closer look when I get it off again.

I did try leak sealing stuff but it didn't work - I have seen that fail for others in the past. Getting the right PTFE tape is now obviously essential to the job going right - the cheap stuff just will not do.

Thanks for the help again. Tom

[Andrew Gabriel]

I usually use 10 turns of PTFE (thin stuff for water). If the tail is not getting stiff when screwing it in, strip it all off and redo with more.

[Rednadnerb]

It's not one of those special offers from Screwfix by any chance? It eventually took 50 turns of (normal thin) ptfe tape to get a seal on the one that I have just put in.

[Tom]

No its from B&Q, but its worth noting the chrome finish is truly appalling to boot. This has to be a parallel valve tail fitting not tapered.

btw. I have just had a cheap one from Screwfix installed by a professional plumber as part of a larger job and there where no problems with that - comparatively the Screwfix rad was one of unbridled excellence.

I have now used about 10-12 turns of PTFE (plumb centre stuff), marking the tail with marker pen so as not to loose track..... and it still leaks. You could well be right about the 50 turns. It wasn't offering nearly as much resistance when screwing in as it should. I'll experiment with more until there is more resistance on screwing it in.

Thanks for the help. Tom

[Andrew Gabriel]

My old (or rather, my dad's old) 1/2" rawlplug cold masonary chisel is an absolutely perfect fit for all the internal key radiator tails I've encountered.

[Tom]

Hi All again, No, getting the tail in and out is no problem - it has an external part that has flat sections that engage easily with and adjustable spanner. It is not the sort that has an internal hex style fitting that need what looks like a large allen key (rad key).

One of the two still leaks - I have tried up to 30 turns of standard PTFE tape (BS L type) and also used Fernox LS-X Leak Sealer on the inner thread - but it still leaks. Why on earth do they make this screw in fitting so utterly leak prone when a lot of plumbing is now push fit. On removal this morning (after leaving it all night to cure) I noticed that the LS-X sealant had been pushed right to the end of the screw in valve tail and was attached to the end like a little crown.

I note that poster Rednadnerb had a Screwfix rad that needed 50 (yeah, 50) turns of PTFE tape to prevent it leaking - mine must be in that league.

I'll give it one last go tonight and then I'll get the plumber back in that did the other one for us.... and guess what? that was a Screwfix rad! That read/valves appeared to have the small valve tail as the one I'm battling with. Tom

[Tom]

The problem with this rad appears to centre on the shallowness of the female screw thread on the rad (I will measure that and post here when its next off). As the valve tail is being screwed in it tears off the PTFE tape by pushing it off to the outside of the rad.

I'm now thinking that either LS-X or liquid PTFE (which is terrible for getting a screw fitting so it can be subsequently undone) may be the only answer. Tom

[Mike Clarke]

Or return it to B&Q as faulty and get a refund.

[Roger Mills]

If the tape is being pushed off, that suggests that you're winding it the wrong way round the tail. Are you sure you're not?

Have you tried the thicker gas-grade tape?

[Spamlet]

Bit late for my two pence worth, but I should think this was a job for ordinary 'RTV' (or any other cheap as you like silicone sealer). If it can hold fish tanks together your tap thread will be no problem. Why bother with ptfe etc when we all have tubes of this lying around. Just don't go mad and block anything up with it (like wot we used to do when 'liquid gasket' first came out...).

S

[Dave]

replying to Spamlet, Dave wrote: I'm having the same problem as the original poster. Got some Aluminium Designer Vertical Radiators, no matter what I do, I cannot stop the tails from leaking. I have tried regular PTFE Tape, Gas PTFE Tape, Joint Compound and Fernox Sealer. I have even tried types of tails, including extendable ones that have a short thread but a rubber seal on the end, thinking this will surely nail it but to no avail. A frustrating and costly mistake buying these rads.

[John Rumm]

Is the leak from the threaded part of the tail that goes into the rad, or when it joins the rad valve?

If its from the threaded section, then only way I can see all those methods failing is if you are not tightening them sufficiently. The tail sections are usually a tapered thread, and so need to be tight enough to bottom out in the socket and compress the sealing tape etc enough to make a proper seal.

[Dave Plowman (News)]

Are you certain they've not split open on a thread? Aluminium is nothing like as strong as steel.

[Rob Morley]

Or perhaps galled from over-tightening the tapered thread, so the sealing face is rough and the thread is stretched and no longer tapered.

[George Ross]

replying to Tom, George Ross wrote: Tom lve got exactly the same problem, b q towel rail, l took my wife with me and the rail l wanted was £30 dearer but she seen a cheep bargain, the threads at the bottom were so course l knew that l would have problems so lm going to follow the advice that you get, if that doesn't work back to b +q and get dearer one Good luck

[tabbypurr]

IME linseed putty always fixes such things, though at times you may also ne ed to pad it with either hemp or unravelled polypropylene rope (cheap rope) . Fill the threads with the linseed.

NT