A radiator valve question

Because of the dire weather I turned on our bedroom radiator t'other night - I don't suppose it's been used more than two or three times in the last three years. It's one of those old simple screw valve jobs, not thermostatic. It's started leaking from under the cowl on the knob, so I guess it's a problem with a sealing gland.

Does anyone know of a cunning way of fixing this without draining down the (pressurised) system? I have a dim memory of a method involving freezing the pipe below the valve, but have never tried it.

Robin.

You should be able to just tighten the gland nut. Phil

If you remove the knob you should be able to tighten the gland nut that is hidden under it. It squashes down on the gland washer / o-ring. No need to drain anything.

If the worst comes to the worst, draining down a pressurised system isn't difficult. The volume of water involved is less than for a header tank (unpressurised) system.

Those freezer systems sort of work but are an expensive way to do the job.

Murray

If per chance you have to drain down, don't forget to add anti corrosion liquid when you re-fill. best done by a funnel and a tube in one of the upstairs rads by removing the air valve and putting it in there. Something like "Fernox" ?
BobH

Most modern radiator valves do not have an adjustable gland nut. When they start leaking you have to replace them.

Mine's a sundial Y plan system with a header tank, so not pressurised (much). Any time I've needed to do jobs of this type I minimise the amount of water drained down by putting a cork in the header tank outlet and locking off all the radiators by shutting down both valves. The amount of water drained from the pipework then 3/4 fills a 2 gallon bucket. I usually return this to the roof tank to preserve the inhibitor content. I can also vouch for the effectiveness of an Adey Magnaclean, which in addition to filtering out any ferrous debris etc also allows for an annual addition of Sentinal X100 direct into the system, with any left overs added to the header tank.

Don Cox

When you drain down you will still get a bit of water out of the rad so a wet & dry vacuum cleaner hose held under the pipe whilst you slowly undo it does help to catch most of the water. Be aware that Fernox in the system will rot the carpet over time so be careful of spillage

I have used the freezing kits to good effect with soldering in new sections of pipe; I suspect the dissatisfaction expressed earlier was down to rushing the job and not letting a proper ice plug develop in the pipe.

I don't think I am breaking any national secrets by saying that a variation of the method is applied to nuclear submarine repairs, using liquid CO2 as the freezing agent. This is a dockyard job to replace components such as a faulty valve in the reactor system, for those operations they install a manned watch to be quite certain a leak in the primary circuit does not take place.

The rest of the system is still kept pressurised for reactor cooling purposes to about 1200 psi and close to 180 degrees centigrade. The ice plug itself is maybe 12 to 15 inches long in these jobs

These repairs are carried out on thick walled stainless steel piping of about 1 inch wall section and the new components are welded into the circuit; all a very far cry away from domestic operations in copper pipe

Brian.

Thanks. There's no obvious way of getting the plastic knob off the valve to expose the innards, which is why I thought i'd have to replace the whole thing. .. Maybe I'll chisel it off and see!

Otherwise I guess I'll have to drain the system and fit a new valve- probably overdue anyway.

Robin

The plastic knob should just pull of, although I have seen them with a screw in the top that has to be removed first - this might be hidden under a glued-on ali disc.

I as suggested seal the header overflow with a 20mm push fit fitting then using a seling kit which is conical rubber bung inserted into the header tank outlet you will create a vacume ,and using a black bin liner fitted around the valve relese the nut and there will be about 1ltr of water which will drain into the liner do not open the bleed valve.You will be able to remove the valve and replace if neccessary.Nerves of steel required.

Frank

Oh dear - spot on. Didn't think of that . Stupidity I suppose! There was indeed a much crudded-up nut underneath, which I have tightened . Thanks - I'd have been pretty sick if I'd got a plumber in, seen him pull the cap off, put on an eighth turn on the nut then charge me 50 quid.

Frank - your method sounds scary! Not sure if I even have a header tank - I thought combi boilers just took water from the main supply without any ancillary gubbins, but plumbing is dark mystery to me, so maybe there is one somewhere...

Robin