Rt40 – Return Temperature Limiting Valve


  • Rt40 thermostatic valves are placed at radiator outlets and are designed to combat the problems of high return temperatures.  For example, those potentially occurring at towel rails, where heat release can be muffled.
  • To prevent over-heating of the return line, the valve limiting temperature is fixed at 40˚C.
  • The Rt40 is bi-directional. The internals can be reversed without having to move the valve out of position. This means that installation errors resulting in water hammer can be easily put right.


  • The Rt40 is a specially adapted Danfoss thermostatic valve. However, instead of reacting to room conditions, the actuator sensor monitors pipe content temperature. It is thus able to respond early to surges and thus keep a tight hold on return temperatures.
  • Rt40 packs come with a lockshield valve, to enable complete isolation of each radiator or towel rail.
  • Both valves can be straight or angled, with finishes in either nickel- or chrome-plated brass. Thermostatic actuators are available in either chrome or white finish. This choice should provide a match with most bathroom applications.
  • Further information of flow rate settings and selection can be found on the Rt40 Data Sheet, available for downloading below.