Why Won’t My Radiator Turn Off? Tips to Fix the Issue

by parker
YouTube video


In this article, we will explore a common issue faced by homeowners – radiators that won’t turn off. As we strive to save energy and keep unused rooms cool, it is important to have functional thermostatic radiator valves that allow us to control the temperature. In this discussion, we will uncover the main causes behind this problem and provide step-by-step instructions on how to fix it. So, if you’re tired of a radiator that won’t shut off, read on!

Understanding Thermostatic Radiator Valves

Thermostatic radiator valves (TRVs) are designed to regulate the flow of hot water into a radiator, based on the desired room temperature. These valves consist of a pin inside the valve body, which is actuated by a wax-filled or gas-filled cartridge. As the room temperature increases, the cartridge expands, pushing the pin down and closing off the valve.

Checking and Replacing the Thermostatic Radiator Valves

  1. First, try turning the existing valve down to its lowest setting, referred to as the “frost set.” If this doesn’t solve the issue, proceed to the next step.
  2. To replace the valve head, turn it all the way up to the highest number before removing it. This step ensures that the pin is fully extended for easy unscrewing.
  3. Check the condition of the plastic pin on the valve head. Over time, these pins may deteriorate and cause the valve to malfunction. Gently push the pin down to check its responsiveness. If it feels stiff or unresponsive, it may be time to replace the valve head.
  4. When installing the new valve head, make sure it is screwed on tightly. Position the arrow on the front for easy monitoring of the valve’s position.
  5. If replacing the valve head does not resolve the issue, it may be necessary to remove the radiator valve body. This step typically involves draining the heating system, so it is best left to professionals or those experienced in plumbing.

Do Radiator Valve Positions Matter?

A common question that arises is whether the thermostatic radiator valve should be placed on the flow or return side of the radiator. In reality, it doesn’t matter as long as the valve is bi-directional and has an indicator arrow showing the direction of flow. If the arrow is present, it must align with the flow of water for proper functionality. However, if you notice noise coming from the valve, it may indicate that the valve is installed incorrectly.

Understanding Temperature Control

It is important to note that thermostatic radiator valves do not directly control the temperature of the water flowing through the radiator. Instead, they control the flow of water into the radiator, which ultimately affects the room temperature. When the valve is set to a lower temperature, it cuts off the flow of water until the room temperature drops. Conversely, when the valve is set higher, it opens and allows a full flow of water to heat the room. The actual temperature control occurs at the boiler, which turns on, off, or reduces the flow of hot water based on the valve’s demand.

Achieving Radiator Balance

In some cases, adjusting the thermostatic radiator valve may impact the heat distribution in other radiators within the heating system. This effect is known as self-balancing. When one radiator is turned on more than others, it may result in unequal heat distribution. To address this issue, a process called radiator balancing can be performed. This involves adjusting the lockshield valve on each radiator to achieve a balanced flow of water throughout the system. Refer to our video on how to balance your central heating system for a detailed guide.


Dealing with a radiator that won’t turn off can be frustrating, but understanding the workings of a thermostatic radiator valve and following the steps outlined in this article can help resolve the issue. Remember to check the valve head, replace it if necessary, and ensure the proper flow direction. If all else fails, seeking professional assistance is recommended to avoid any potential plumbing mishaps. By taking the necessary steps, you can regain control of your radiators and maintain a comfortable and energy-efficient home.

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