Last updated on January 8th, 2025
Turning off a radiator might seem simple, but older heating systems can pose challenges. Unused radiator valves often seize, leak, or break when operated after years of inactivity. With over a decade of experience repairing and replacing radiators, I’ve handled all types of valves. In this guide, I’ll show you how to safely turn off a radiator based on my hands-on experience.
How to turn off a radiator
To turn off a radiator you must close one of the valves at either side of the radiator. You can close any of the two valves to turn it off or you can close both valves if you want to remove the radiator.
Having a good pair of water pump pliers is best for turning lockshield valves as it’s much quicker and easier than using an adjustable spanner. Water pump pliers can also grip rounded-off valves or manual valve handles when they are too stiff to turn with your hand.
Thermostatic radiator valve
To turn a radiator off with a thermostatic valve you must turn it clockwise until it’s on ‘off’ or ‘0’. You can also turn it to frost setting (if you have one) which means the radiator will stay off unless the temperature drops to below 5 degrees in that room.
Manual valve
With a manual valve, you need to turn it clockwise with your hand as far as it will go. You might need to start it off by using some water pump pliers as they can be tight when they haven’t been turned for years.
Lockshield
For lockshield valves, you must remove the cap and turn the valve clockwise as far as it will turn with an adjustable spanner, water pump pliers, or some valves will need a hex key to turn it. You should be able to pull or screw the cap off with your hand, but some will have a screw in the middle that needs to be removed first.
Towel radiator valve
Turning off a towel radiator is usually easy as they mostly have manual valves. You can turn either one of the valves clockwise as far as it will turn. You might need to use some water pump pliers to get it going.
How to turn down a radiator
Turning down the temperature of radiators is different from turning down the temperature of the room thermostat. The thermostat feels the temperature of the room and cuts the boiler (or radiator using TRV) off when the room reaches the set temperature.
Turning down the temperature of the radiators turns down the heat of the radiators to touch, the hotter the radiators the quicker the room will reach the temperature set on the thermostat. The typical temperature of radiators is 65°C whereas a typical room thermostat is set around 20°C.
Turning down a radiator:
At the boiler
To turn the temperature of a radiator down you can turn the heating/radiator dial on the boiler down, but this will turn down all of the radiators.
Thermostatic valves
You can also turn the thermostatic radiator valve down to a lower setting but the temperature of the radiator will remain the same as before. The radiator will turn off when the temperature of the room has reached what the thermostatic valve is set to.
Lockshields
The best way to turn a radiator down properly is to partially close a lockshield radiator valve. This is how to balance radiators. You must turn the valve clockwise as far as it will turn and close it using some water pump pliers or an adjustable spanner. Then open it a quarter turn, keep opening it slightly until it’s at the temperature you want.
How to check radiator valves are open
One radiator not working is sometimes caused by the valve being closed without knowing that it’s closed. To check radiator valves are open you need to turn the valves anti-clockwise as far as possible.
If the radiator valve does not turn anti-clockwise then try turning it clockwise to see if it’s moving. If it doesn’t move either way then it must be stuck and you’ll need to force it to free it. The best way is with a decent pair of water pump pliers.
Summary
Turning a radiator off is very simple most of the time, especially if you have thermostatic radiator valves. Just remember to turn any valves clockwise to turn them off and anti-clockwise to turn them on.
There are times when turning off a radiator goes bad like when it causes a radiator valve to leak because it hasn't been touched for so long. In which case you'll need to replace the valve.
Feel free to ask any questions in the comments below, and I’ll do my best to help. If you found this post helpful, please consider sharing it.
Really appreciate the clear instruction and explanation on this page Steven. I’ve just had a radiator leak on my Lockshield valve and you’ve saved me a lot of trouble before I can get a plumber into to replace parts. Thank you very much!
Hi Steven, When my heat is on high about 27 all radiators are hot if I turn it down to about 19 the last 4 in the system won’t heat up why.
Hi David,
That’s a strange one. I’m assuming it’s a large system. The only thing I can think of is it takes a long time to heat up the full system properly so by the time the heat has reached the last radiators, the room which the thermostat is in has already reached 19 degrees so it cuts the boiler out.