How Do Thermostatic Radiator Valves Work

By Trinity

11th Nov 2022

4 mins read

DIY & Technical

Thermostatic Radiator Valves are a helpful way to maximise the control you have over your home heating. Find out how they work and why you need them!

chrome radiator valve

What is a Thermostatic Radiator Valve?

There are plenty of ways to make your heating more efficient and TRVs are a great place to start.

TRV stands for Thermostatic Radiator Valve. They’re valves that can be added to specific radiators in your home so that you don’t have to rely on a general thermostat to control the entirety of your heating. It’s fairly easy to install a TRV too!

Thermostatic radiator valves are a helpful way to maximise the control you have over your home heating. They allow you to control the heat from an individual radiator, meaning that you can vary the heating settings room to room in your home. They’re essentially the old school version of smart heating systems.

white radiator valve

How Do Thermostatic Radiator Valves Work

Thanks to a sensor fitted into the valve, TRVs are self regulating. They can adjust the flow of hot water into your radiator in relation to what temperature you have set your valve to. The sensor detects changes in room temperature, causing the valve head to either expand or contract. This movement adjusts the spring, causing the valve to open or close.

When the temperature of the room increases, the valve head expands. This causes the valve to close so that less hot water can make its way into the radiator to prevent an increase in heat.

radiator valve diagram

So, when the room temperature drops, the valve contracts. This results in the valve opening to let more hot water in so that the room temperature can be maintained at the level you set it to.

It’s worth noting that this is why it’s not recommended to use a TRV in your bathroom. Temperature changes created by the use of a shower or bath will have an impact on the overall room temperature. Therefore, its ability to self regulate would be compromised.

TRVs typically have a setting range from 0-5. Each number on the valve roughly represents the room temperature you wish to maintain:

  • 0 = Off
  • * = 7°C
  • 1 = 10°C
  • 2 = 15°C
  • 3 = 20°C
  • 4 = 25°C
  • 5 = 30°C

Benefits of TRVs

There are two types of TRV: wax TRVs and liquid TRVs. Each comes with their own advantages.

Wax TRVs

Wax TRVs are typically found on older radiators. Whilst they are often less expensive than liquid TRVs, the wax is less sensitive to changes in temperature. This means they make take longer to adjust to the temperature in the room.

Liquid TRVs

Although a slightly more expensive option, liquid TRVs are more sensitive to temperature change. Therefore, they’ll adjust the temperature of your radiator much more efficiently.

Black radiator valves

One of the best features of TRVs is that because they adjust to internal temperatures according to the setting you have chosen, you don’t have to adjust them when outside temperatures change. So come winter or summer, your TRVs should keep your home at your desired temperature.

Due to their ability to self regulate, TRVs are actually a very cost and energy efficient solution to heating. The sensor is a TRV will mean that your radiator won’t overheat, or continue to heat your room for too long. As a result this can save you energy and money.

So TRVs as it turns out can be super helpful when it comes to controlling the heating in your home! If you’re looking for a way to optimise your heating that also requires minimal effort, why not give TRVs a go?



Trinity is one of our expert bloggers in bathroom design and DIYs. Read her blog posts for the latest coverage of style trends and easy-to-follow guides.

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