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Radiator valves are easy to overlook until they stop doing their job.

Whether one has started leaking, seized up or simply isn't controlling the temperature properly anymore, replacing it can often restore your radiator to full working order without replacing the whole unit.

This guide explains the different types of radiator valve, how to replace them safely, and when it's worth calling in a heating engineer instead.

Quick answer: Can you change a radiator valve yourself?

Replacing a radiator valve is a DIY job that many confident homeowners can tackle, particularly if you're replacing like-for-like and only working on one radiator.

For the best chance of success:

• Turn off the heating before you start

• Isolate the radiator or drain the system if needed

• Count the lockshield valve turns before closing it

• Use PTFE tape on new threaded connections

• Bleed the radiator once you've finished

• Check carefully for leaks before leaving the system running

Types of radiator valve

Before you start, it helps to know which valves you're actually dealing with. Every radiator has two, usually of different types:

• Manual valve: Turned by hand to control the flow of hot water into the radiator. They're common on older heating systems

• Thermostatic radiator valve (TRV): Recognisable by its numbered dial, a TRV automatically adjusts the flow of hot water to help maintain the room temperature you've selected

• Lockshield valve: Usually hidden beneath a plastic cap on the opposite side of the radiator. It's used to balance the heating system rather than for everyday temperature control

Reasons to change a radiator valve

People usually replace radiator valves because:

• The existing valve is leaking

• It has become stiff or seized

• The radiator no longer heats properly

• They're upgrading to thermostatic radiator valves (TRVs) for better temperature control

• They're refreshing the look of older radiators during decorating

Make sure you choose the right size, style, and function for your radiator before buying. Not all valves fit all radiators, and TRVs come in straight or angled versions depending on your pipework.

What you'll need

• New valve (and TRV head, if upgrading)

• Radiator bleed key

• PTFE tape

• Hose (for draining, if needed)

• Adjustable spanner and grips

• Old towels

• Cloth or wire wool

• Bucket or container

How to change a radiator valve (draining the system)

If you're replacing several valves at once, draining the heating system is usually the simplest approach. Before you begin, allow the system to cool completely to avoid working with hot water.

1. Turn off your central heating and allow the system to cool completely. If necessary, isolate the heating system following your boiler manufacturer's instructions before draining the radiator

2. Lay down towels, then connect a hose to the radiator's drain cock and run the other end outside

3. Open the drain cock and use your bleed key to help all the water drain out

4. Hold the valve body steady with grips while you unscrew the retaining nuts with a spanner

5. Remove the old valve and clean any debris from the connection with a cloth or wire wool

6. Wrap the new valve's connection threads with PTFE tape

7. Fit the new valve, aligning the cap-nut over the pipe along with the sealing components

8. Tighten both cap-nuts – the one joining the valve to the adapter, and the one securing it to the pipe

9. Turn the water supply back on and bleed the radiator again to clear trapped air

10. Turn the central heating back on and let the system refill

11. Repressurise your boiler if needed, following your boiler's instructions

How to change a radiator valve without draining the system

Draining a full central heating system is time-consuming and messy. If you're only replacing one valve, you can usually avoid it. But while this method can save time, it does leave less room for error. Have plenty of towels and a container ready before loosening any fittings.

1. Switch off your water supply and central heating

2. Remove the cap on the lockshield valve and turn the spindle clockwise as far as it will go – count the turns so you can return it to the same position afterwards and keep your system balanced

3. Close the valve on the opposite end of the radiator (turn a manual valve clockwise fully, or a TRV to its lowest setting)

4. Lay down towels and have a container ready to catch drips

5. Remove the head from the old valve, undo the retaining nuts, and wrap the new valve's threads in PTFE tape

6. Open the bleed valve briefly to let trapped air escape, then close it again

7. If your lockshield valve has a drain-off point, open it to drain just that radiator into a container

8. Loosen the top nut nearest the radiator on the valve you're replacing, using a wrench and spanner, and let the remaining water drain out

9. Remove the old valve by unscrewing both nuts once drained

10. Fit the new valve, tighten both cap-nuts, and screw the valve head into place

11. Turn the water supply back on and reopen the lockshield valve to the same number of turns you counted in step 2

12. Bleed the radiator and repressurise the system if needed

Can you change a radiator valve yourself — and should you?

Replacing a radiator valve is well within the abilities of many confident DIYers, especially if you're working on just one radiator and the existing pipework is in good condition.

DIY is usually suitable if:

• You're replacing a single valve

• The radiator and pipework are in good condition

• You're confident draining and bleeding a radiator

• You have the right tools

It's usually worth calling a heating engineer if:

• The valve is badly seized

• The pipework is corroded

• Several valves need replacing

• You're fitting multiple TRVs

• You're unsure about repressurising or balancing the system afterwards

Replacing the valve is often the easy bit. It's making sure everything stays leak-free afterwards that can catch people out.

Thinking about hiring a professional?

Replacing a radiator valve is usually a fairly quick job for an experienced heating engineer.

They'll make sure the new valve is fitted correctly, check for leaks, and confirm the radiator is heating properly before they leave.

If you're replacing valves throughout your home, they can also rebalance the heating system so every radiator warms up as it should – something that's easy to overlook when doing the work yourself.

Perhaps most importantly, you'll have the reassurance that everything has been installed correctly, without wondering whether a small drip might turn into a bigger problem later.

Radiator valve replacement checklist

• Turn off the heating before you start

• Identify which valve type you're replacing

• Count the lockshield valve turns before closing it

• Have towels and a container ready

• Use PTFE tape on new threaded connections

• Bleed the radiator afterwards

• Check carefully for leaks

• Repressurise and rebalance the system if needed

Find checked and reviewed heating engineers near you

If you'd rather leave your heating system in experienced hands, a local heating engineer can replace faulty radiator valves quickly, safely and with minimal disruption.

With Checkatrade, tradespeople are:

• Checked - Every Checkatrade member must pass up to 12 checks and commit to upholding the Checkatrade Standard

• Reviewed - Over 6.2 million reviews have been published on Checkatrade about real jobs, on everything from communication, tidiness, timekeeping, and quality of work

• Guaranteed - Jobs booked through Checkatrade are covered up to £1,000 (T&Cs apply)

Whether you're replacing one faulty valve or upgrading your whole heating system with TRVs, search for checked and reviewed heating engineers near you and get the job sorted with confidence.

FAQs

What's the difference between a TRV and a manual valve?

A thermostatic radiator valve (TRV) automatically adjusts the flow of hot water to maintain the room temperature you've selected. A manual valve simply controls whether the radiator is on or off, with the room temperature managed by your central heating controls.

Do I need to change the lockshield valve too?

Not usually. The lockshield valve balances water flow between radiators and rarely needs replacing unless it's damaged. If you do replace it, count how many turns it takes to close so you can return it to the same balanced position.

Can I change a radiator valve without draining the whole system?

If you're replacing a single valve, you can often isolate that radiator without draining the whole heating system. If you're replacing several valves, draining the system is normally the easier option.

How do I know if my radiator valve needs replacing?

Common signs include leaks around the valve, a valve that won't turn, or a radiator that doesn't respond properly when you adjust the temperature. If you're unsure whether the valve is at fault, a heating engineer can diagnose the problem.

Do I need to bleed the radiator after changing a valve?

Yes, bleeding removes any air trapped in the system while you were working, which can otherwise cause cold spots or noisy radiators.

Will changing radiator valves affect my boiler's pressure?

It can. Draining and refilling part of the system often drops the boiler pressure slightly, so check your boiler's pressure gauge afterwards and repressurise if needed, following your boiler manual's instructions.

Can I upgrade just one radiator to a TRV?

Yes. Many homes have a mixture of manual valves and TRVs, so it's perfectly fine to upgrade them one at a time if that's what suits your budget.

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