Drip, Drip, Drip: What to Do When a Radiator Springs a Leak

Is there anything as annoying as finding a pool of water that’s collected underneath a radiator, soaking right through your carpet and into the floor and possibly the floorboards? And making an unsightly distraction in the corner of the lounge right when you’re about to have family or friends over to your home?

Well, either way, it’s clearly irritating and makes for rather a worrying development, at that. Why has your radiator started leaking? Has it developed a fault and if so, what can you do about it before any major damage is done to your home?

Get Prepared

Before isolating the problem and moving on to fix it, you’ll first need to make sure you’re prepared for what’s to come in the next steps. That means preparing for the worst-case scenario – water potentially gushing out your radiator as you investigate and / or try to fix the problem. So, first, it’s imperative you lay down on the floor under and around the radiator in question some towels or other absorbent material. You’ll also definitely want a bucket to hand – safety first!

Repairing a Leaking Valve

So, if you discover it’s a radiator valve to blame, how do you go about fixing it? Well, like it or not, you’re going to have to start off by draining down the system to a level below where the leak itself is occurring. Start off then by switching off the supply valve (where water’s allowed into the radiator) and also the Lockshield valve (the one that should be sited on the side of the device and is topped by a plastic cap). Be sure your towels (and, if necessary, a bucket) catches any water that’s emitted at this stage.

Now, by deploying an adjustable spanner, undo the nut to be found between the feeder pipe and the radiator itself (this is a union nut) and then open the bleed valve, so the radiator can be drained of the rest of the water it contains (which should be collected in the bucket).

So, to actually repair the faulty valve, locate the male end of its valve tail and, with care, wrap around it PTFE tape up to 15 times to securely cover over – and make water-tight – the gap through which the leak’s occurring. Then re-tighten the union nut, reopen both the bleed and Lockshield valves and, once water’s been restored to the system, check there are now no leaks and close fully the bleed valve.

Replacing a Radiator Valve

First things first; if you discover you’ve no alternative than to remove your faulty valve and replace it with a new one, you’re going to have to choose and purchase a new valve. It may be obvious, but you’ll have to do your homework first; be sure, whatever the radiator model you have – whatever the brand; whether it’s among their vertical radiators, say, or towel radiators – that the valve is right for the unit and will align correctly with the water pipe.

With a replacement valve in your possession; again, you must drain the radiator – and the central heating system of all its water (of course, if you’ve any electric radiators in any rooms of your home, it’ll be possible to use these still; as they’ll run independently of the system).

Then, unscrew the nuts that connect the faulty valve to the pipe, remove the valve and clean the threads at the radiator’s end before you install your new valve. Now wrap PTFE tape around the valve’s adaptor threads before screwing it into the radiator’s end – without over-tightening it and so not harming the fixing (before you’ve even used it!). And, over the pipe’s end, slide the valve’s cap-nut and an olive to help hold it in place, then connect the valve.

You’ll now be able to fill up the system once before – but don’t forget to bleed this radiator and the others in the system to remove any unnecessary, built-up air.


What If the Valve Gland Is Leaking?

Now, it might be you’ve found the gland, which is located under the valve’s plastic cap, is the trouble-making source of the leak. How to put this right? Quite easy, actually; with PTFE tape. So, turn off the valve and turn off the Lockshield valve too if water’s still leaking.

Remove the cap, carefully unscrew the gland nut with your adjustable spanner and wrap about 20cm of PTFE tape around the valve’s spindle – the bit of the valve that’ll now be obviously sticking up. Taking a (small, ideally) flat-headed screwdriver, push the tape down in the valve and, using silicone grease, screw the gland nut back on and tightly into place, before putting the cap back and switching on the valve once more. Hey, presto!

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