[SOLVED] Sticking Thermostatic Radiator Valves (2026 Update) Solved

Found this old thread by Googling the problem and slackening off the brass nut worked a treat. Many thanks Andy, what a relief not having to replace the valve.

Just been grappling with this problem. We have a red hot rad’ and l’ve not been able to release the valve following plumbers’ advice on You Tube vids. Been hesitant to touch the brass nut but will give it a go as it seems to have worked for others. Thanks Andy Bennet for the advice.

Just been grappling with this problem. We have a red hot rad’ and l’ve not been able to release the valve following plumbers’ advice on You Tube vids. Been hesitant to touch the brass nut but will give it a go as it seems to have worked for others. Thanks Andy Bennet for the advice.

When Thermostatic Rad Valves stick, they tend to stick closed. The usual ‘tapping’ trick is to open them.

If the rad is hot, the valve is open.

Either the head isn’t fitted correctly or the head is damaged. The temperature sensitive bit is in the head, it presses on the pin.

If the pin is ‘up’ the valve is open. Use something metal to push it down. If it moves, it isn’t stuck. I’ve never seen one stick open. A ‘tap’ on the side of the body normally frees a stuck closed / down pin. ( Remove the head first.)

One of my TRVs has just developed a drip from the centre pin area - I say developed, really it's a problem we had last winter that I thought I had fixed by working the pin up and down and adding WD40. Now it's back and quite a lot worse, so I've had to put a bowl under it.

I don't think I can replace the valve myself as there is no way of shutting off the water to the rad without draining the system.

Or you can do it without freezing or draining down. I have used the method described in this video twice and no floods.

Richard

May not work too well when close to a massive amount of water/metal such as a radiator. The use always seems to be demonstrated on a length of copper with no nearby fittings that act as a heat store (albeit at ambient temperature)

I can assure you that i have had an entire radiator freeze and split...:-)

Probably climate change. Or Brexit. Or some 'far right' plot.

-- “it should be clear by now to everyone that activist environmentalism (or environmental activism) is becoming a general ideology about humans, about their freedom, about the relationship between the individual and the state, and about the manipulation of people under the guise of a 'noble' idea. It is not an honest pursuit of 'sustainable development,' a matter of elementary environmental protection, or a search for rational mechanisms designed to achieve a healthy environment. Yet things do occur that make you shake your head and remind yourself that you live neither in Joseph Stalin’s Communist era, nor in the Orwellian utopia of 1984.”

Vaclav Klaus

With a single 300ml can of freezer spray @ £30 ?

Rarely necessary to drain a whole system. If it’s a sealed system with an expansion vessel and pressure gauge, just depressurise the system, close off the lockshield valve and drain the radiator down from the other end with something to catch the water. Once the radiator is drained down, very little water will come out of the rest of the pipework. If you can get the same TRV (or at least one with he same fittings and dimensions) you should be able to swap the old one out.

If you have an open vented system, you will need to seal the feed and expansion pipes with suitable bungs. Then proceed as above.

Tim

UPDATE - Tried Andy B’s suggested solution and pleased to say it worked. The half turn on the brass nut released the pin, allowing movement up and down. Re-tightened the nut and the rad seems to be working fine maintaining the set temperature. Thanks Andy.

UPDATE - Tried Andy B’s suggested solution and pleased to say it worked. The half turn on the brass nut released the pin, allowing movement up and down. Re-tightened the nut and the rad seems to be working fine maintaining the set temperature. Thanks Andy.

Best thing to catch the water -

Paint roller trays have always done it for me.

Might get one of those for next time - but £10 for a bit of plastic . . .

Agreed, but the one shown is getting too full to empty without spillage.

Agreed, but the one shown is getting too full to empty without spillage.

A wet’n’dry vacuum cleaner is your friend in these situations. ;-)

Tim