Return temperature is a term describing the return water temperature in a heating system. This term is used for both sub-components and for a complete heating system.
In a heating system that is connected to a district heating system, requirements regarding the maximum return temperature are often specified by the district heating provider.
Thermostatic return temperature limiters are used to regulate applications such as small under-floor heating installations, hot-water tanks and radiators. The water must first cool to a preset value before a valve will open, allowing it to flow. If a thermostatic return temperature limiter is used, for example, in under-floor heating, it does not regulate either the room temperature or the heat output. It only regulates the return temperature.
This can lead to uncomfortably high room temperatures and higher energy consumption.