A radiator valve is an important component of a central heating system. It regulates the flow of hot water to the radiators and can be found near the boiler or under-floor heating systems. If your radiator valve isn’t working properly, it could cause major problems for your home. In this guide, we will explain everything you need to know about changing a radiator valve.

What are the two valves on a radiator for?

Radiator systems in homes and buildings have two essential valves. They play distinct but equally important roles in controlling the flow of hot water and regulating the temperature within a room.

Thermostatic radiator valve (TRV)

The thermostatic radiator valve, often referred to as the TRV, is the valve you’ll typically find at the top or side of a radiator. Its primary function is to control the temperature of the radiator itself. This valve contains a thermostatic head that can sense the ambient temperature of the room. Based on this temperature, it adjusts the flow of hot water into the radiator.

Temperature control: The TRV allows you to set a desired temperature for the room. When the room is colder than the set temperature, the TRV opens, allowing more hot water to flow through the radiator, which in turn heats up the room. Conversely, when the room reaches the desired temperature, the TRV begins to close, reducing the heat output.

Energy efficiency: One of the significant benefits of a TRV is its ability to enhance energy efficiency. It prevents rooms from overheating, which can occur with non-thermostatic valves, ultimately saving energy and reducing heating costs.

Lockshield valve

The lockshield valve, on the other hand, is often located at the opposite end of the radiator from the TRV. This valve serves a different purpose entirely. While the TRV controls the temperature, the lockshield valve is used for hydraulic balancing of the heating system.

Balancing the system: Balancing is essential to ensure that all radiators in the heating system receive an equal amount of hot water. It prevents some radiators from getting too hot while others remain too cold. A properly balanced system ensures even heating throughout the building.

Adjusted by a professional: Unlike the TRV, which homeowners can adjust to their desired room temperature, the lockshield valve should be adjusted by a heating professional. They will make sure that each radiator in the system receives the right flow of hot water, preventing issues like uneven heating and energy waste.

When do you need to change your radiator valve?

You might consider changing your radiator valve for several reasons:

  • Leakage: If you notice water seeping from the valve, it’s a clear sign that a replacement is in order.
  • Noisy or stuck valve: Radiator valves can sometimes become noisy or get stuck in one position. This can affect the radiator’s performance and your comfort.
  • Upgrading to a TRV: If you want more control over the temperature in a room, you may want to upgrade to a thermostatic radiator valve.

Is it easy to change a radiator valve?

Yes, changing a radiator valve only requires some basic tools and knowledge of how plumbing works. You don’t need any special training or experience! However, it’s essential to follow the proper steps to ensure a safe and effective replacement.

How to change a radiator valve?

Now, let’s change a radiator valve according to the following 6 steps.

Step 1: Switch off heating system and shut off water.

Before you start, it’s crucial to ensure your safety and prevent any accidental scalding or water damage. Follow these steps:

Turn off the heating system: Locate your boiler or heating system and switch it off. This prevents hot water from circulating through the radiator while you work on it.

Shut off the water supply: Locate the isolation valves on both the flow and return pipes connected to the radiator you intend to work on. These valves are typically located on the pipework leading to the radiator. Turn both valves clockwise to shut off the water supply to the radiator. This step is essential to prevent water from spilling out during the valve replacement.

Step 2: Locate the drain off.

Next, you’ll need to drain the water from the radiator. To do this, follow these steps:

Prepare a container: Place a bucket or container under the radiator’s drain-off valve. This valve is usually located at the bottom of the radiator and resembles a small tap.

Open the drain-off valve: Using a radiator key or an adjustable wrench, carefully open the drain-off valve by turning it counterclockwise. Allow the water to flow into the container. Be prepared for some water spillage and have towels or rags handy to clean up any spills.

Step 3: Remove the old radiator valve.

Now, you’ll replace the old valve with a new one. Here’s what to do:

Use a wrench: Carefully use a wrench to loosen and remove the old radiator valve. Turn it counterclockwise to unscrew it from the radiator. Be prepared for some water to come out during this process.

Step 4: Fit the new radiator valve.

With the old valve removed, it’s time to install the new one:

Apply PTFE tape: Wrap some PTFE (polytetrafluoroethylene) tape around the threads of the new valve. This tape helps create a watertight seal.

Screw in the new valve: Carefully screw the new radiator valve into the radiator’s outlet. Use a wrench to tighten it, ensuring it’s securely attached. Be cautious not to over-tighten, as this can damage the valve or the radiator.

Step 5: Turn the mains water back on.

Now that the new valve is in place, it’s time to restore the water supply:

Check for leaks: Before turning the water supply back on, double-check for any leaks around the new valve and connections. Ensure everything is secure.

Open the isolation valves: Turn the isolation valves on the flow and return the pipes counterclockwise to open them. This will allow water to flow into the radiator.

Observe for air: As the radiator fills with water, you may notice air escaping through the bleed valve at the top. This is normal and part of the process.

Close the bleed valve: Once water flows steadily from the bleed valve, close it to prevent further air from entering the radiator.

Step 6: Bleed the radiator.

To ensure optimal performance, you need to bleed the radiator to remove any trapped air:

Use a radiator key: Attach a radiator key to the bleed valve, usually located at the top of the radiator. Turn the key counterclockwise until you hear a hissing sound. This means air is escaping. Keep turning until water starts to flow steadily, then close the valve.

How to change a radiator valve without draining the system?

If you want to replace the radiator valve without draining the system, there are a few extra steps. Here’s a detailed guide:

Tools and Materials You’ll Need

  • Adjustable wrench
  • PTFE tape (polytetrafluoroethylene tape)
  • Towels or rags
  • Bucket or container
  • Plastic bags and zip ties (optional)

Step 1: Turn off the heating system

Locate your boiler or heating system and turn it off. This is crucial to prevent hot water from circulating through the radiator you’re working on.

Step 2: Prepare for water leakage

Understand that there may still be some water leakage during this process. Place towels or rags around the base of the radiator to catch any water that might escape.

Step 3: Loosen the lockshield valve

Identify the lockshield valve, typically located on the opposite end of the radiator from the thermostatic valve. Using an adjustable wrench, carefully loosen the lockshield valve by turning it counterclockwise. Be prepared for a small amount of water to escape.

Step 4: Attach a hose

Take a length of hose and securely attach it to the now-loosened lockshield valve. Use a hose clamp or zip tie to ensure a tight fit. Place the other end of the hose into a bucket or container to catch the water that will come out.

Step 5: Remove the old radiator valve

Similar to the first procedure, use a wrench to unscrew and remove the old radiator valve. Expect some water to escape during this step.

Step 6: Replace with the new valve

Wrap PTFE tape around the threads of the new radiator valve. Carefully screw the new valve into the radiator outlet and tighten it with a wrench. Again, avoid over-tightening to prevent damage.

Step 7: Close the lockshield valve

Once the new valve is securely in place, close the lockshield valve by turning it clockwise. This will prevent any further water from flowing into the radiator.

Step 8: Remove the hose

Carefully remove the hose from the lockshield valve, being mindful of any remaining water in the hose. Seal the end of the hose with a plastic bag and a zip tie to prevent any drips.

Step 9: Turn on the heating system

Turn the heating system back on. This will pressurize the system and allow hot water to flow into the newly installed valve.

Step 10: Bleed the radiator

As the radiator fills with water, you may need to bleed it to release any trapped air. Use a radiator key on the bleed valve at the top until water flows steadily, then close the valve.

Step 11: Check for leaks

Inspect the area around the newly installed valve for any leaks. If you notice any, carefully tighten the connections.

Changing a radiator valve without draining the system can be more complex due to the potential for water spillage and the need for precise valve adjustments. If you’re not comfortable with these steps or have any doubts, it’s advisable to seek the assistance of a professional plumber to ensure a successful and safe valve replacement.

Alternatives to changing a radiator valve.

If you don’t want to replace your radiator valve, we have some alternatives to solve the problem.

Servicing and maintenance

Before jumping into a full replacement, it’s often a good idea to have a professional plumber or heating technician service and clean your existing radiator valve. Over time, valves can accumulate debris, which can affect their performance. A thorough cleaning and maintenance check may resolve issues like sticking or noisy valves.

Radiator valve repair kits

There are repair kits available for some types of radiator valves. These kits typically include replacement seals and components that can help fix common issues like leaks or drips. If your valve is serviceable, this can be a cost-effective option.

Balancing the system

If you’re experiencing uneven heating in your home, it may not necessarily be a problem with the radiator valve. Instead, it could be an issue with the balance of your heating system. A professional can assess and balance the system by adjusting lockshield valves on all radiators to ensure even heat distribution.

Radiator reflectors

Radiator reflector panels can be installed behind radiators to reflect heat back into the room. This can improve the efficiency of your radiator and reduce heat loss through external walls, making your heating system more effective without changing the valve.

Radiator boosters

Radiator boosters are devices that can be fitted to radiators to improve heat circulation in the room. They use a small fan to distribute warm air more effectively, making your radiator work better without altering the valve.

Is your new radiator valve the right size?

Before you purchase a new radiator valve, it’s important to measure the size of your current one. You can do this by placing a piece of paper under your radiator and measuring its height from top to bottom (in millimeters).

If your current valve does not match up with what’s recommended for your new radiator, there are two options:

  1. You can choose a different style of valve that will work well with your existing setup.
  2. You can install an adapter kit that allows you to use two different-sized valves at once.

How much to change a radiator valve?

The cost of changing a radiator valve can vary based on factors such as location, labor rates, and the type of valve you choose. On average, it costs between $30 and $60 for an experienced technician to replace a single radiator valve with no other work involved. Replacing all two valves will cost you anywhere from $50 – $100.


In conclusion, changing a radiator valve can be a manageable task with the right guidance. However, if you’re unsure or uncomfortable with the process, it’s always wise to seek professional assistance to ensure safety and efficiency. If you want to learn about the details of changing a radiator valve, please contact us at 0086 186-2391-5479.


Why change your radiator valves?

Changing radiator valves can address various issues, including leaks, noise, or the desire for better temperature control. Upgrading to thermostatic radiator valves can also enhance energy efficiency and comfort in your home.

Can I change a radiator valve myself?

Yes, changing a radiator valve is a DIY project for those with basic plumbing skills. Just ensure the heating system is off, shut off the water supply, and follow the step-by-step guide to do it safely.

How do you remove a radiator valve?

To remove a radiator valve, first, turn off the heating system and water supply. Then, use an adjustable wrench to carefully unscrew the valve counterclockwise. Be prepared for some water to escape, so have towels or a bucket ready to catch it.

How to replace a radiator valve leaking?

If you have a leaking radiator valve, start by turning off the heating system and water supply. Drain the radiator, ensuring it's tightly sealed to prevent leaks.

How do you replace a radiator vent valve?

To replace a radiator vent valve, use a radiator key to unscrew the old vent valve counterclockwise. Replace it with a new vent valve, ensuring it's securely tightened. This can address issues like hissing or trapped air in your radiator.

How often should you replace your radiator valves?

Radiator valves typically last many years, but consider replacement if they start leaking, become noisy, or if you want to upgrade to thermostatic valves for better control.

About the author

About the author

Yunchong Shang

Yunchong is a seasoned boiler expert with over five years of hands-on experience in the boiler industry. He has expertise in various types of boilers, including fire-tube, water-tube, and steam boilers, while also staying up-to-date with the latest technological boiler.

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