How TRVs Work

A thermostatic radiator valve (TRV) controls the flow of hot water into a radiator automatically, in response to room temperature. The valve head contains a wax element that expands as the room warms, pushing against the valve pin to reduce flow, and contracts when it cools to allow more hot water in. Most TRV heads use a dial numbered 0–5: 0 is fully closed (frost protection) and 3 equates to approximately 20°C in a standard system. TRVs cut energy use by preventing individual rooms from overheating without requiring a dedicated thermostat in every room.

Angled, Straight and Corner TRVs

The three TRV configurations match different pipe layouts: angled for pipes entering from the floor or side, straight for pipes entering directly beneath the radiator, and corner for horizontal wall pipes. All use standard UK G½ threaded connections. Browse Radiator Valves for the full range, Radiator Pipe Covers & Rosettes to conceal the pipe entry, or browse Vertical Radiators and Horizontal Radiators for compatible radiators.