Radiator valves

[MattN]

A few weeks back I removed a radiator in order to decorate. Last night I refitted the radiator and placed kitchen towel under each end of the radiator to highlight any leaks. Overnight, there haven't been any drips BUT one of the radiator valve tails is slightly moist. This is strange because I only disconnected the radiator from the pipes and took it off the wall, I didn't dismantle the radiator itself (maybe I should have done, though). What's the best course of action - leave it for a few days to 'settle', drain the radiator and wrap PTFE tap around the thread and replace, buy a new valve,....?

Any suggestions will be very welcome.

 

[masona]

Try using White Hawk Jointing Compound which is very good for this.

You sometime can get away with it if you're carefully undo the nut applying light pressure to stop it coming apart and put compound then tighten it up.Be prepare if it go wrong

 

[MattN]

Thanks for the suggestion.

So, I guess that I would close both the valves (to stop the flow), put a container underneath the tail to catch the spillage, loosen the nut, remove the old PTFE tape, wrap fresh PTFE tape around the thread, then apply some of this joint compound, then re-tighten the nut (how tight? As tight as possible??). Is it best to do this in-situ, or actually drain the radiator and remove it from the wall?

I only ask because I've had a few nasty shocks with plumbing recently (a lockshield valve that failed and wouldn't close, for example) so I'm pretty hesitant to tackle anything water-related at the moment!!

 

[masona]

Sorry I must've mis-read your post.

Can you tell us where is the leak on what part of the radiator valve?
The copper pipe side to the valve,the rad valve side connected to rad or the valve splindle etc.

If it's leaking round the thread then re-apply with ptfe tape.If you're not confident then drain the system down and shutdown all radiator valves.Do the valve tight but not overtighten

 

[MattN]

Ok - it would appear that the moisture is appearing on the nut that is closest to (virtually touches) the radiator (the nut that tightens the valve tail into the radiator's bottom?), not the nut the tightens the radiator to the copper pipe (well, the lockshield/wheelhead valve). I'm starting to wonder whether it's best just to drain the radiator and remove it - then replace the valve tail (better to be safe than sorry?).

Going back to draining the system, I guess I need to locate the drainage point (obvious!) - is this likely to be downstairs near the boiler? Do you just push a hose onto it and open it?

Also, some of the stopcocks are really tight - is WD40 the best lube to use in order to free these?

All these questions, eh! Sorry.....

 

[masona]

Sound like to me the rad valve not seated in correctly or not enough ptfe tape on the thread or the nut not tighten enough.You can try give it another little turn on the nut (don't cross thread it) and support the valve with a stillson to prevent twisting.

Draining the system you don't say what type of system you have combi,non-combi,gravity system etc..

And yes the stopcock can be right ******* to undo not sure if anything is better than WD40 ?

 

[Scoby_Beasley]

Plus gas (penetrating oil) is better than wd40 for getting into seized/locked threaded components, as it says, it penetrates, whereas wd40 is a moisture dispersant.
Another tip with siezed bolts/nuts (anywhere) is to try and tighten them slightly before undoing, this will help to break the grip that has built up.
When you can control your stopcock, open fully, then back it off just a tad, the taps then already going in the right direction the next time you need to touch it.
With regards weeping joints, the old way to fix them was with some hemp strands wrapped in the thread direction and then painted with a gloss paint (colour unimportant!!) then tighten the nut onto the wet paint.
On tightening the nut, do as much as you can by hand without forcing, then give the spanner a short sharp lean, this will be the correct torque setting !!!!

 

[ChrisR]

To help undo tight stop cocks etc, slacken the gland nut (on the shaft), & heat gently

 

[MattN]

Cheers for all the info.

The moisture 'weep' appears to have stopped - it'd be nice to know whether this is gonna prove to be a weakness in the future, but I'm not complaining right now!

I finally managed to hunt down the central heating (gravity hot water, pumped heating) drainage point - it has been partially covered with a wooden box, next to the boiler!! To gain access to it I'll need to remove this 'feature' off the wall. I've absolutely no idea why someone would do this..... So, if I ever need to drain the system it's gonna turn into a whole lot of fun.

On the stopcock front, it'd seem that it has freed but has a very slight weep from the spindle (which we've noticed for a while now). Is this simple enough to cure? The two stopcocks in the airing cupboard, however, look like they're ready to disintegrate if I dare to disturb them.

Thanks for your time guys,

MattN