How to replace a broken radiator valve

How to replace a broken radiator valve

Valves are a small but very important part of a central heating system as they are responsible for allowing water to flow in and out of radiators. At some point during the life of most radiators, there comes a point where a valve needs replacing. This could be due to the fact it has become damaged in some way or it might simply be old and worn due to years and years of use. Additionally you might have decided to upgrade to a thermostatic radiator valve (TRV) or it could be that your old valve no longer matches your interior decor.

Whatever your exact reason, knowing how to correctly replace a radiator valve is a really useful skill to have. It's rarely a hugely complicated task and, with a little guidance, it's a job that you are capable of carrying out yourself. In this article, we'll take you step by step through replacing a radiator valve so that you can get your radiators and central heating system running as efficiently and effectively as possible.

Why you might replace a radiator valve

As hinted at in the introduction to this article, there are usually just a few main reasons why you might have decided that your existing radiator valve needs replacing. We'll touch on those most likely scenarios below.

The valve is old and worn out

Over time, the wear and tear on old radiator valves can lead to worsening performance and functionality. Continuous usage, exposure to varying temperatures, and the natural aging process can cause components within the radiator valve to deteriorate. This can result in issues such as leaks, inconsistent heating, or difficulty in adjusting temperatures. Corrosion and mineral deposits can also accumulate within the valve, causing it to become stiff or seize up completely. These factors collectively contribute to the degradation of the valve's effectiveness over time, making replacement of the valve a necessary step to ensure your radiator is performing effectively and efficiently. 

The valve has become damaged or broken

Due to their position on the outside of a radiator, radiator valves are susceptible to damage or breakage due to things like accidental impact, corrosion, or faulty internal components. Physical damage, whether from knocks, bumps, or other incidents, can cause cracks or fractures in the valve body, compromising its integrity and leading to leaks. Additionally, exposure to moisture can accelerate corrosion, weakening the valve and causing it to deteriorate over time. Faulty internal components, such as worn seals or malfunctioning pin mechanisms, can result in issues like leaks, erratic temperature control, or complete valve failure. In such cases, replacing the damaged or broken radiator valve with a new one is essential to ensure efficient and reliable operation of the heating system, preventing further damage and maintaining optimal comfort levels in your home.

You're changing to a thermostatic radiator valve (TRV)

Upgrading from an old manual valve to a new thermostatic radiator valve is very common as TRVs offer several benefits that justify the switch. Firstly, TRVs provide enhanced control over room temperatures by automatically adjusting the flow of hot water based on the desired temperature setting, ensuring a more comfortable and consistent heating experience. This automation eliminates the need for manual adjustments throughout the day, optimizing energy efficiency and potentially reducing heating costs. Additionally, TRVs offer greater precision in temperature regulation, allowing homeowners to customise heating levels according to individual preferences and usage patterns. 

You're updating your old valves to match your decor

Updating a radiator valve to complement the decor of a room is a popular choice among homeowners seeking to enhance the aesthetic appeal of their living spaces. By selecting a valve that look great with the overall style and theme of the room, such as modern, traditional, or minimalist, you can elevate the visual appeal of your home while maintaining functional heating capabilities. With a wide variety of styles, finishes, and designs available in the market, ranging from sleek chrome finishes to classic brass or ornate designs, there are ample options to suit diverse tastes and preferences.

How to replace a radiator valve

Tools you'll need

  • Adjustable spanner
  • Pair of grips
  • Old towel or sheet (to protect the floor)
  • Water receptacle (just in case)
  • WD40

Step 1 - Switch off your central heating

Make sure your whole central heating system is turned off. You don't want to be dealing with any hot water water spilling our or your heating system trying to come on when there is no water in the system. Ensuring everything is off befor you start the job will simply make everything safer and easier.

Step 2 - Drain your heating system

After your heating system has been switched off and allowed to cool for around 30mins, you will need to drain the system of water. If you have a combi boiler you can follow the following steps:

- You will be able to drain the water from the system by locating the drain cock and securely attaching a hose to it.
- After ensuring that you have covered the floor in rags or towels to catch any leakage, you should close the valves.

If you have a conventional cylinder tank, it is best to seek professional help.

Step 3 - Remove the old valve

Securing the body of the valve with grips you can then unscrew the capnuts and remove the valve. Then unscrew the valve cap nut to remove the old valve. At this point, it's a good idea to take the opportunity to thoroughly clean the pipe with wire wool to remove any rust or grime.

Step 4 - Fit the new valve

Unscrew the valve adaptor from the radiator. Wind PTFE tape four or five times around the threads of the new adaptor and screw it into the end of the radiator.

You can then fit the new valve, but do not tighten the cap-nut just yet. Holding the valve body with a spanner or grips, line it up with the adaptor and tighten the cap-nut. After this, you will be able to tighten the cap-nut that holds the valve to the water pipe.

Step 5 - Refill the system

Now that your broken radiator valve has been replaced you will need to refill the system before you can get it back up and running.

To refill the system find the filling loop beneath the boiler and turn the valve. Increase it until the pressure gauge reaches 1 ½. Follow our advice on how to bleed a radiator then once you have bled your radiators, turn the filling loop valve on the boiler again. Increase it until the pressure gauge reaches 1 1/2.

Remember not to carry out any work without being sure of what you will be doing. It can be dangerous and may end up causing greater problems with your central heating system. If you are in any doubt seek professional help.

How to change a radiator valve without draining the system

It takes time to drain your central heating system down, so that part of the process can be a bit frustrating if you're in a hurry to get the job done. While we recommend that you drain your system if you are replacing valves across multiple radiators, if you only need to change one valve then you can get away without needing the drain your system.

If you aren't experienced with plumbing tasks then you should drain your system or consult a professional. However, if you are confident in your abilities, please follow the instructions below on changing a valve without draining your heating system.

Tools you'll need

  • Radiator bleed key
  • Adjustable spanner
  • Pair of grips
  • Old towel or sheet (to protect the floor)
  • Water receptacle (just in case)

Step 1 - Turn off heating

With your equipment arranged nearby, it's time to begin. Start by ensuring both your heating and water supply are completely turned off. This precautionary step helps avoid accidents or unwelcome spills. Additionally, set all thermostats to 0 to prevent any system activation during your work.

Step 2 - Protect the floor

To mitigate potential water spillages, it is advisable to place towels or old rags beneath the radiator and surrounding pipes to safeguard the flooring. This preventive measure helps contain any leaks, spills or drips, maintaining the cleanliness and integrity of the area during the task.

Step 3 - Prepare your valves

Preparing your valves is a simple step can effectively prevent any potential leaks. If you're replacing a TRV, start by removing the heads from both the old and new valves. Next, dismantle the nuts and connectors from the new valve to ready it for attachment to the radiator. Prior to installation, apply jointing compound to the parts that will connect to the radiator. For added leak prevention, consider wrapping PTFE tape around the connector approximately eight to ten times. 

Step 4 - Bleed the radiator

Use your bleed key to open the radiator bleed valve and release any trapped air. Once the air has escaped, close the valve securely. You can read more on doing this in our guide on How to Bleed a Radiator

Step 5 - Open the old valve

Begin by opening the existing thermostatic or manual valve. Secure the valve body with a grips while using a spanner to loosen the top nut. This action will initiate the flow of water and air from the radiator. Ensure you have a suitable container nearby to capture the water, as it will continue to flow for a few minutes until the radiator is fully drained.

Step 6 - Remove the old valve

To avoid any spillages, wait until the water has completely stopped flowing out of the radiator. You can then remove the old valve completely.

Step 7 - Fit the new valve

Begin by unscrewing the valve adaptor from the radiator. Next, wrap PTFE tape around the threads of the new adaptor four or five times before securely screwing it into the end of the radiator. Proceed to install the new valve, ensuring not to tighten the cap-nut immediately. Hold the valve body with grips, align it with the adaptor, and then tighten the cap-nut. Finally, tighten the cap-nut securing the valve to the water pipe.

Step 8 - Refill the system

Turn your water supply back and and allow water back into the system. Make sure to reopen your lockshield valve so that water can flow into the radiator.

Step 9 - Bleed your radiator

This process may have caused air to form in the top of your radiator, so go through the step of bleeding your radiator until all the trapped air has escaped.

Step 10 - Repressurise (if necessary)

If you have a pressurised heating system (for example, you have a combi boiler) then you will probably need to repressurise your system. For more information, you read our guide on How To Repressurise a Central Heating System.

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