What are Thermostatic Radiator Valves and do I need them?

A Thermostatic Radiator Valve, or TRV, is a clever little device that fits onto your radiator and lets you control the temperature of each room individually. Instead of your whole house being one set temperature, TRVs sense the air temperature around them and automatically adjust the flow of hot water to the radiator.

This means you can save energy by not heating rooms you aren't using, or by keeping spaces like bedrooms slightly cooler than your living room.

Do I need to have Thermostatic Radiator Valves?

If you're getting a new boiler, then yes. Government regulations in England are designed to improve the energy efficiency of our homes. According to the official guidance, any home having its boiler replaced should also be fitted with thermostatic room controls.

This means every room should have either:

• A thermostat to control that specific room or zone.
• A radiator with a Thermostatic Radiator Valve (TRV).

The most common and cost-effective way to meet this requirement is to have a main thermostat in a central location, with TRVs fitted to radiators in all other rooms. Your main thermostat, ideally placed on an interior wall away from direct sunlight or draughts, will work with your boiler and the TRVs to keep your home perfectly comfortable and efficient.

It's important to note that you should not have a TRV on the radiator in the same room as your main thermostat. The two controls would essentially fight each other; the TRV might shut the radiator off when the room is warm, but the main thermostat could still be telling the boiler to keep running to heat other areas, leading to an inefficient system.

How do Thermostatic Radiator Valves work?

It's simpler than you might think. The head of the TRV contains a capsule of wax or liquid that expands when the room warms up.

As it expands, it pushes a pin that closes the valve, reducing the flow of hot water into the radiator. This stops the radiator from getting any hotter.

When the room temperature cools down, the substance in the head contracts. This releases the pin, opening the valve and allowing hot water to flow back into the radiator to warm the room up again.

What are the benefits of Thermostatic Radiator Valves?

When used correctly, TRVs are a small change that can make a big difference.

Save money on bills

By not wasting energy heating empty rooms, you can make significant savings. The Energy Saving Trust estimates that installing and correctly using TRVs could save a typical household in Great Britain around £110 per year. A study by BEAMA found TRVs could cut energy use by up to 41% under certain temperature conditions, with an average energy saving of 18%. 

Save energy and reduce your carbon footprint

Because your boiler doesn't have to work as hard to heat the entire house to one high temperature, it uses less fuel. This not only lowers your bills but also reduces your home's carbon emissions, which is better for the planet.

A more comfortable homea

Being able to set different temperatures in different rooms means everyone can be comfortable. You can keep the living room cosy for a movie night while leaving the spare room on a low, frost-protection setting. It also means you can set the optimum comfortable temperature for each space, like keeping your bedroom slightly cooler for a more restful night's sleep without getting too hot.