How to Cool a Radiator That Won’t Turn Off

by parker
YouTube video


Radiators are an essential part of heating systems, but sometimes they can become problematic. Many people know how to fix radiators that aren’t heating up, but what about those radiators that won’t turn off? In this article, we’ll be discussing why your radiator might be stuck in the “on” position and how you can safely cool it down. We’ll provide step-by-step instructions and useful tips to help you troubleshoot this issue and save energy in the process.

Understanding Thermostatic Radiator Valves

One common cause of a radiator that won’t turn off is a faulty thermostatic radiator valve (TRV). TRVs regulate the flow of hot water to the radiator based on the temperature in the room. They contain a pin or cartridge that expands and contracts with temperature changes, allowing or restricting water flow accordingly.

Step 1: Check the TRV Pin

If your radiator won’t turn off, the first step is to check the TRV pin. Start by removing the valve head by unscrewing it counterclockwise. You might want to turn the valve up fully before removing the head to make the process easier. Inspect the pin for any signs of damage or obstruction. If the pin is stuck or not functioning properly, it may be the cause of the issue.

Step 2: Adjust the Valve Setting

Before replacing the valve head, make sure the valve setting is correct. Turn the valve down to the frost setting, which is typically indicated by a snowflake symbol. This setting ensures that the radiator will only turn on if the room temperature drops below a certain level, usually around five degrees Celsius.

Step 3: Reassemble and Test

Once you’ve checked the pin and adjusted the valve setting, reassemble the valve head by screwing it back on clockwise. Make sure it is hand tight but not overly tight. Position the arrow on the valve head facing towards you for easy monitoring. Now, try turning the valve down to see if it successfully closes off the water flow. If the radiator still doesn’t turn off, it may be necessary to remove the radiator valve body.

Step 4: Draining the System (Advanced Option)

If you’re comfortable with plumbing and want to take further steps to cool your radiator, you may consider removing the radiator valve body. This process requires draining the heating system, so it’s important to have a good understanding of plumbing and the necessary tools. If you don’t feel confident in doing this yourself, it’s best to consult a professional plumber to avoid any potential water damage or system malfunctions.

Two-Way Flow and Noise Issues

Some people wonder whether it matters if the thermostatic radiator valve is placed on the flow or return side of the radiator. The truth is, as long as the valve is bi-directional, it doesn’t matter. Bi-directional valves are designed to work in either direction, and they usually have an arrow indicating the flow direction. However, if you hear noise coming from your radiator valves, it could be an indication that the valve is on the wrong way around, hindering the proper flow of water.

Understanding How TRVs Control Temperature

It’s important to note that thermostatic radiator valves do not directly change the temperature of the water flowing through the radiator. Instead, they control the flow of water, enabling it to either heat the room or stop the flow when the desired temperature is reached. Lowering the valve setting doesn’t decrease the water temperature; rather, it stops or reduces the flow of hot water to the radiator, allowing it to cool down.

The Self-Balancing Nature of Radiator Valves

One interesting aspect of TRVs is their ability to self-balance the system. When a radiator is turned off or the flow is reduced, other radiators in the system may receive more heat. This balancing effect helps maintain a consistent temperature throughout the house. However, if you notice that one radiator is receiving significantly more heat than others, you might need to balance your central heating system. There is a separate video available on how to balance your central heating system if you need further guidance.


Dealing with a radiator that won’t turn off can be frustrating and wasteful of energy. By following the steps outlined in this article, you can troubleshoot the issue and potentially save on heating costs. Remember to always prioritize safety and consult a professional if you’re unsure about any plumbing tasks. With the right knowledge and approach, you can ensure that your radiators operate efficiently and provide you with the desired level of comfort in your home. Stay warm and save energy!

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