What is a Thermostatic Radiator Valve (TRV)?

‘TRV’ might sound like a model of car, but it actually stands for Thermostatic Radiator Valve. It’s an improved version of a manual radiator valve and using TRVs can give you greater control of your heating so you only use the energy you need. Here’s how they can help you go greener.

How does a thermostatic valve work?

A thermostatic radiator valve is that little thing on the side of your radiator, and if you’ve ever wondered what a TRV is and how it works, then rest assured that it’s pretty simple. Essentially, by fitting TRVs to your radiators, you can control the temperature in each room individually. Thermostatic radiator valves detect the temperature of the room, then adjust the radiator so that the room is as warm as you want it. TRVs have a numbered dial, usually from 0 to 5, with each number corresponding to a temperature range, typically:

  • 1 = 10°C
  • 2 = 15°C
  • 3 = 20°C
  • 4 = 25°C
  • 5 = 30°C

So you can have a toasty lounge set to 3 or 4, with the empty spare room set to 1 or an already oven-warmed kitchen set to 2, for example. All you need to do is turn the dial on the TRV in each room so it is only as warm as you want it. This greater control over your heating can help reduce the amount of energy you use, which can in turn save money.

Okay, but how does a thermostatic valve really work?

Ah, you want the nitty gritty. A TRV comprises a head and a body and it controls the flow of water to your radiators. When the room reaches the set temperature, it stops radiators from getting any hotter.

  • When the room temperature changes, the head expands. It then moves a pin into the valve body
  • If the temperature’s too hot, the valve closes and stops the hot water coming to the radiator
  • If it’s too cold, the valve opens and lets more hot water in to reach the set temperature

Do I need a room thermostat with thermostatic radiator valves?

Nope! TRVs do the same job as a room thermostat so you don’t need both.

What’s the difference between a manual radiator valve and a TRV?

Manual radiator valves can only switch radiators on or off, while thermostatic radiator valves can set the temperature to a specific range. Smart TRVs go one better and let you select the exact temperature you want.

What are the benefits of thermostatic radiator valves?

Greater control of your home

With a TRV, you can set the temperatures low for rooms that aren’t used a lot, while regulating the temperature in the main rooms.

Make use of natural heating

If you’ve got big windows that let in a lot of natural light, you’ll get some extra heat too. So when there is additional heat in the room, be it from light or lots of people, the TRV will detect it and turn the radiator off accordingly.

Reduce energy use and bills

The key benefits of TRVs is that they can help you stop heating parts of your home that you don’t need to. Which means you’ll be reducing your energy usage and saving money.

How do I fit thermostatic radiator valves?

Switching to thermostatic valves is nothing to worry about. They can be changed quite easily, or of course you could get us to kit the whole house out for you.

If you want to get thermostatic valves installed in your home, book a free appointment and one of our trusted engineers will come round to discuss it and give you a fixed-price quote.

What are smart radiator valves and are they worth it?

With smart radiator valves, you can enjoy all the benefits of thermostatic radiator valves, but with even more functionality. The first main difference between thermostatic radiator valves and smart radiator valves is that you can select the exact temperature of your room, rather than a range. And the second is that you can control your heating right from the palm of your hand with smart TRVs, as they can be managed remotely through a smartphone app.

If you have a Hive Thermostat or Hive Mini, then you can use the familiar Hive app to control all your radiators fitted with Hive Radiator Valves. There’s no need to adjust each individual TRV in your home, you can do them all while sitting on the sofa. Or while riding the bus or waiting in line in the Post Office.

But you don’t need a Hive Thermostat to benefit from Hive Radiator Valves – you can still save energy and money controlling them manually rather than via the app.

Don't forget to check out our guides for more DIY tips and help on how to improve your home's efficiency. 

Frequently Asked Questions

How do you change a thermostatic radiator valve without draining the system?

You can do this if you’re getting a smart replacement, such as a Hive Radiator Valve, or only replacing one valve. It’s simple, just unscrew the existing valve and replace it with the Hive one.

Is it easy to fit a thermostat on a radiator?

Yes, with Hive Radiator Valves you simply unscrew your existing radiator valve and put the new one on. However, if you’re kitting out your home with all new TRVs, it’s worth draining the system first:

  • Drain the system and let the air out. Bleed your radiators and once you’re done, you can remove the old valve
  • Pull the cover off the valve using grips and an adjustable spanner to reveal the pipework underneath
  • Loosen the pressure fitting on the bottom of the valve and then take off the valve
  • Fit on the new thermostatic valve and start putting it all back together
  • If the TRV doesn’t fit on the valve insert, you may need to remove this. Use a hex tool, adjustable spanner, and PTFE tape to remove it, wrap it up and install the new insert that comes with the TRV

Don’t fancy the DIY option? We can do it for you, just book a free quote.

Which side does the thermostatic valve go on a radiator?

Although nowadays it could go on either side, a thermostatic valve should go on the side of the radiator where the hot water goes into it.

How does a thermostatic radiator valve work?

Once the temperature in your room reaches the level set on your thermostatic radiator valve, the radiator stops heating up the room. You can set different temperatures for different rooms.

Is it worth fitting thermostatic radiator valves?

Definitely. Thermostatic radiator valves are a good investment to keep tighter control over your heating and so reduce your energy use – and our carbon footprint. Smart thermostatic radiator valves will take the savings up a level.

How accurate are thermostatic radiator valves?

Very! They’re precise in regulating radiator temperature and can sense the temperatures you set and maintain them.

Are smart radiator valves worth it?

Of course! Like anything, sometimes a thermostatic radiator valve might cost more than a regular one but in the long run, you’ll be saving money.

What are the best smart TRVs?

It all depends on what type you’re after. If you want TRVs that you adjust manually, there are many to choose from. But if you thrive in the digital age and want a smart thermostatic radiator valve, then the Hive Radiator Valves could be perfect for you. Of course, there are other smart valves out there which will be compatible with your smart device, so it’s always worth shopping around.