Your radiator’s seemingly simple numbered radiator control is more significant than you might think. Known as TRV radiators or thermostatic radiator valves, these devices are crucial to managing the heat management of your home’s rooms. Adjusting the water flow into the radiator ensures the temperature varies ideally with your settings and the room’s needs. Whether you’re considering Drayton thermostatic radiator valves, Danfoss thermostatic radiator valves, or traditional thermostatic radiator valves, they’re all about saving energy and enhancing comfort. Yet, like any radiator regulator, they can encounter issues, such as a thermostatic radiator valve being stuck or leaking. For these common radiator valve problems, considering a radiator valve replacement might be wise. Understanding how thermostatic radiator valves work is essential for efficient Heat Management and avoiding the frustration of a thermostatic radiator valve not working.

Why do thermostatic radiator valves stick?

The top of the valve consists of a wax capsule that is heat sensitive and, therefore, expands and contracts. As it swells and shrinks, it pushes down on a pin within the lower section of the valve body. The pin pushes down on the washer that regulates how much water flows through the valve and into the radiator.

In the summertime, when your central heating is turned off, the valve head or the wax capsule will become hot through the increased summer temperatures and will push down on the pin. The consistent warmer summer temperatures often mean the pin remains in the same position for the entire summer. When winter comes, it is not uncommon for the washer to be stuck within the valve, preventing the radiator heating up.

To prevent the TRV from sticking, the best thing to do at the end of the heating season would be to open the valve so that it is fully open. You can then turn the heating system off.

How to fix a stuck thermostatic valve

Identify the Issue: Confirm if the valve’s pin is stuck. This is a common issue, but one that can be resolved with some know-how.

  • Remove the Valve Head: Carefully detach the valve head to access the problematic area. This step is crucial for getting to the heart of the problem.
  • Gentle Tapping: With the head off, lightly tap the centre pin. This action helps in freeing the washer, ensuring the valve control mechanism works smoothly.
  • Avoid Complete Closure: Never fully close the heating valve. Keeping it slightly open prevents unwanted moisture build-up.
  • Prevent Moisture Damage: A fully closed valve can lead to dampness. This not only harms your valve exhaust system but can also cause mould, discolouration and pose health risks.

For comprehensive insights into plumbing fixes, including DIY solutions for a leaking shower, visit our dedicated section on plumbing fixes.

Other thermostatic valve
problems include


Avoid putting TRVs on radiators that are in the same room as the room thermostat.
It is possible to put a TRV on every single radiator in your house. However, it would be advisable to not put one on radiators within the room where the room thermostat is sited. This room is sensing the temperature and you want the temperature to rise and spread throughout the house. When the room temperature reaches the level you have selected on the room thermostat controls, it will then shut off all the radiators. Because the room thermostat controls the valve, that controls the whole of the central heating system.


Avoid putting TRVs inside radiator covers.
If you have got radiator covers, you should not place thermostatic valves inside the covers. The covers will trap a certain amount of heat, meaning you will get a higher temperature reading inside the cover than inside the room. Instead, consider purchasing a TRV that can protrude through the side of the cover. Depending on how your cover has been designed, it may be possible for you to have an external sensor (to ensure it senses heat outside the cover). External sensors are simply a very small rectangular box (approx. 5cm high and 1cm deep) that sit outside the radiator casing.

How To Fit a Thermostatic Radiator Valve 

Replacing traditional radiator valves with thermostatic ones (TRVs) can significantly improve your home’s heating efficiency and comfort. Here’s a straightforward guide to making the switch: 

  • Turn Off the Heating: Ensure your heating system is off and completely cool to avoid burns or leaks. 
  • Drain the Radiator: You’ll drain the specific radiator to replace the valve. Open the bleed valve and catch any water that comes out. 
  • Remove the Old Valve: Use an adjustable wrench to loosen and remove the old radiator valve. Be prepared for residual water by having a towel or bucket handy. 
  • Clean the Valve Area: Before installing the new TRV, clean the pipe threads and the area around the valve connection to ensure a smooth installation. 
  • Install the TRV: Thread the new thermostatic valve into place by hand to avoid cross-threading, then tighten it with a wrench. Ensure the TRV points in the correct direction for airflow and control accessibility. 
  • Refill the Radiator: Close the bleed valve, then slowly refill the radiator, checking for leaks as you go. This step is crucial to avoid air pockets and ensure efficient operation. 
  • Test the System: Once installed and the radiator refilled, turn your heating system back on. Adjust your new TRV to different settings to ensure it is effectively controlling the temperature. 

For those interested in broader plumbing knowledge, such as understanding the expert strategies for water stop valve operation or tackling other plumbing issues, call Maintracts at 020 8131 5245. 

Importance of Regular Radiator Valve Maintenance 

Regular maintenance is critical to preventing radiator valve issues. Routinely checking your heating valve and valve control systems can ward off inefficiencies, leaks, and the need for costly repairs. This proactive approach optimises your heating system, ensuring a warm and comfortable home environment.  

For those looking to delve deeper into maintaining their home’s plumbing system effectively, understanding and operating the toilet isolation valve can be incredibly beneficial. 

All in all, thermostatic radiator valves are great devices if you are looking for ways to save energy at home. For instance, let’s say you live in a large house over three floors. We all know heat rises, so you might find the top floor rooms getting too hot. In which instance, a thermostatic valve would mean you could turn the radiators in those rooms down to a very low setting. Then, if the room started to get a little chilly, the radiator would come on. Essentially, you will only be using heating energy when and where it is needed, rather than blasting out heat all over the house when you only need it in one or two rooms.

Malcolm Osmore
Managing Director at Maintracts Services

If you are unable to get your radiator working properly and prefer to leave the hard work to the professionals, you know where to find us. We’re here for all your radiator and heat control needs.