Thermostatic radiator valves look similar, but the wrong choice creates installation problems and returns. This guide covers the three decisions that matter most when selecting which models to stock.
Body pattern comes first. A straight valve is used when the pipe comes up from the floor, an angle valve when the pipe comes out of the wall, and an axial valve on one-pipe systems or where pressure drop must be minimised. Most markets need all three.
Sensor type is the second decision. Wax sensors are cheaper but react slowly and lose accuracy over years of cycling. Liquid-filled sensors respond faster, hold their accuracy longer and show almost no hysteresis, which is why they dominate the European replacement market.
Finally, consider whether the market requires presetting. In larger buildings, radiators close to the heat source need to be throttled so that distant radiators still receive enough flow. A valve with a presetting ring allows this balancing to be done at commissioning.
For distributors, the practical approach is to stock straight, angle and axial patterns in G1/2 inch as the core range, add G3/4 inch for larger radiators, and keep a small quantity of presettable models for commercial projects.