You may encounter a nasty surprise with the radiator valves when you turn on your heating, but also during use at full capacity in the winter months. 

How radiator valves are made 

These radiating elements have two valves: an inlet and an outlet (“return”) for water. The main valve is controlled by a radiator knob which can simply be a handwheel or a thermostatic valve. The latter is a normal shut-off valve screw that is opened and closed with a screwdriver. 

What problems can radiator valves have? 

After sitting for a few months while the heating is turned off, these valves may be difficult to both open and close as a consequence of hardened limestone, ferrous or other powder deposits. It is fundamental to avoid forcing the rotation of handwheels and valves because the consequences could be disastrous: there is a lot of water in the heating system and it could cause leaks or drips whose repair would require emptying the system and calling a plumber. 

A handwheel that doesn’t turn 

This is one of the most frequent problems, especially if was closed forcefully at the end of the last winter. We can initially unscrew the handwheel by acting on the screw that locks it to the control shaft. Remove the handwheel and the plastic ring nut below. You should see the movable pin which activates the closing valve. Apply a little WD-40 Specialist Fast Release Penetrant, which quickly penetrates the mechanism and lets the parts move freely, with remarkable effectiveness. Its formula is also suitable for difficult cases of gripping and oxidation. It is water-resistant and therefore very suitable for taps. Then replace the ring nut and the handwheel. 

The thermostatic valve won’t turn 

This repair is similar to the previous one. The only difference is that you must remove the thermostatic valves. You usually just have to unscrew the metal ring nut that fixes it to the threaded connection of the radiator. Also in this case, the control shaft can be seen and you can do as described above. It’s also possible that it won’t rotate due to the locking of mechanisms inside the valve. In this case, look for access areas where you can spray WD-40 Multi-Use. Otherwise, the valve probably needs to be replaced. 

The screw shut-off valve is blocked 

After having unscrewed its protective cap, try using a screwdriver to loosen or tighten it. If it doesn’t move, apply some WD-40 Specialist Fast Release Penetrant. Once unblocked, apply WD40 Specialist High Performance PTFE Lubricant spray, which provides lubrication and protects the mechanism, significantly reducing friction. Ideal for components or mechanisms exposed to water, it can be applied after the Super Unlocking spray (or instead of it) on handwheels as well as thermostatic valves. 

Want more DIY tips and tricks? Why not read more of our blogs such as how to remove silicone sealant, how to remove rust from a bike or how to fix a squeaky hinge.