Thermostatic Radiator Valves (TRVs) control the temperature of individual radiators by regulating water flow based on the room's temperature. They're a legal requirement on most new boiler installations and a worthwhile retrofit on older systems.
How TRVs work
A TRV has a wax capsule that expands or contracts based on room temperature. When the room reaches the set temperature, the capsule expands and reduces water flow through the radiator. No electricity needed — it's entirely mechanical.
Why they save money
A bedroom you sleep in at 15°C doesn't need to be heated to the same temperature as your living room. TRVs allow zone control without complex wiring — each radiator is independently controlled. The Energy Saving Trust estimates TRVs save £75–£90/year on a typical household.
Building Regulations requirement
Under Part L of the Building Regulations, all new boiler installations must include TRVs on all radiators except the one in the room with the main thermostat. This has been mandatory since 2005.
Smart TRVs
Smart TRVs (Tado, Netatmo, Drayton Wiser) allow app control, scheduling per room, and geofencing per room. A major upgrade in convenience and efficiency for larger homes. We install smart TRV systems from £79 per room.