Our Guide to Thermostatic Radiator Valves

Radiator valves are an essential part of how our homes are heated. They control the flow of hot water through pipes and ensure your radiator heats up efficiently and effectively. 

Thermostatic radiator valves do this exact job, however they are one of the many heating controls that can be used for modulating radiator temperatures within different rooms.

What are smart TRVs?

Smart TRVs are designed to provide the same room by room heating control, connecting to your thermostat to create the zoned heating system. 

However, smart TRVs can be electronically controlled through apps for smartphones, tablets and computers. This means whether you’re at home, or out and about, you’ll be able to control your home’s heating from a simple app.  You are also able to adjust each room individually at different times and different temperatures using the app.

Are TRVs a legal requirement?

As part of the new rules in England, in newly built homes or homes which have had a boiler replaced, TRVs must be installed in every room. 

This is part of the UK government’s mission to increase the energy efficiency of new and existing homes. 

How do thermostatic radiator valves work?

TRVs are made up of two parts: the thermostatic head and the valve body. 

The thermostatic head contains an actuator that expands and contracts as temperature rises and falls. The valve body has a sprung plunger inside that closes and opens the supply of water into the radiator.

Expansion as the room heats blocks the valve to receive less hot water into the radiator. 

Contraction as the room cools opens the valve to receive more hot water in the radiator. 

How do thermostatic radiator valves connect to your radiator?

TRVs attach to the top of your radiator’s flow pipe valve body, which is the pipe which pumps the water into your radiator. 

You will need a qualified Plumbing & Heating Engineer to fit new thermostatic radiators valves for you as your heating system may need to be fully drained and refilled. 

Can I put TRVs on all of my radiators?

You can put TRVs on most radiators in your home, however, there must be a suitable bypass  installed between the flow and return. There must also be a suitable system interlock which shuts off the heating once a desired temperature has been reached. 

You don’t need to put a TRV on any radiators which are in the same room as your room thermostat. Your heating engineer will be able to advise you on this.

Where should thermostatic radiator valves go?

Most modern TRVs are bi-directional, meaning they can be fitted on the flow or return pipe of your radiator. 

However, it is always best to fit the TRV on the flow pipe that enters your radiator. 

How to set thermostatic radiator valves

Thermostatic radiator valves have numbers or symbols on them representing how much heat the radiator is putting out. 

When correctly fitted, the TRV will automatically detect the temperature in the room and let more or less hot water into the radiator depending on what setting you have the valves on.

What do the settings on thermostatic radiator valves mean?

The numbers on thermostatic radiator valves refer to the temperature in the room, not the temperature of the radiator. When the temperature drops below these temperatures, the TRV will allow hot water to flow to the radiator. 

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

Fully functional TRVs will detect the temperature of the room and automatically adjust the amount of hot water in the radiator accordingly. 

Cost benefits of thermostatic radiator valves

Thermostatic radiator valves can help you to save money by allowing you to adjust the temperature on different radiators in your home. 

TRVs have been known to reduce energy bills by around 40%, since you only heat up rooms in your home that need to be heated, rather than turning on every radiator in your home. 

However, how much you can save with TRVs will depend on several factors including your insulation, the performance of your radiators and the number of rooms you regularly heat. 

How long do thermostatic radiator valves last?

Ordinary thermostatic radiator valves last around 15 years, but some more expensive, higher quality ones may last longer than this.