Want to know more about TRV's.


So we all walk past them all the time, but do we really know what they are, what they do and how they do it? 

Stick with us and we’ll turn up the heat on the subject!


A Thermostatic Radiator Valve, or TRV is the part on your water filled radiator that opens to allow flow into your radiator, in turn allowing it to heat. 

The TRV is made up of two major parts, the “Valve Body” and the “TRV Head”. 


The Valve body is the metal part Shown in Red on our image. 

This has a Pin at the top which when pressed down stops flow into the radiator, this is spring loaded and returns to the Open/Raised position when no force is applied, allowing flow. 

The pin on Valve bodies tend to stick when not actuated for a long period, such as through the summer, so come the winter you may find your radiators stuck in the “Off” position with the pin stuck in. We can combat this using Electronic TRV Heads which will routinely open and close the valve through the summer to ensure it does not stick. 


The TRV Head is the part that screws on top of the Valve Body, normally these are White plastic, but can also be found in Chrome and other decorative metal finishes. 

Modern Replacements can come in Electronic Timed, Bluetooth, Z-Wave, WiFi and many other guises. 


On traditional TRV’s the inner workings use a Wax or Liquid sensor, this expands and contracts with the Air Temperature opening and closing the Pin on the body. 

You turn the traditional TRV to a Number or the “Frost” symbol, this sets the approximate temperature the TRV will open and close at. Often these open and close temperatures are quite variable, and you may find a room drifts between being slightly too hot to too cold within the same day with them. 

On modern Electronic TRV’s there is an Electronic Sensor which is much more accurate that traditional sensing so you will have a much more stable temperature.

All TRV’s limit the upper temperature of the room, when the room is below a TRV’s set point the heating system needs to be informed so the boiler can switch on and supply heat. 


Electronic TRV’s can bring a host of benefits over traditional models. 

As previously mentioned, in periods of good weather your valves will not function, over a long period this can cause the inner parts of the Valve body to seize up. Electronic TRV’s often cycle the valve to avoid this happening and keep your system healthy and ready for winter. 

Electronic TRV’s with timers allow you to limit the upper temperature of a room through the day and week, for example you can limit the temperature of your bedrooms through the day when they are not in use saving you energy costs. 

Certain TRV’s can report back to their Controller or linked Thermostat and tell the boiler to turn back on. In this case the TRV is in control of the Upper and Lower temperatures of the room giving you total control of every room 


Modern TRV’s are a great way to get your individual room temperatures under control improving the comfort of your home dramatically and can save you significant amounts of money in reduced energy wastage. 

Combined with a Home Control System where you can turn off individual rooms when their windows are open or turn rooms on when guests are staying your options are nearly limitless.