The ESBE series GFA is a circulation unit with an adjustable constant outlet temperature used to keep the flow temperature at the set level regardless of pressure drop or flow volume. The thermostatic valve is the number one choice for under floor heating systems requiring a scald safe* function, which is important in order to protect under floor heating pipes and also the floor itself. *) Scald safe means that in case of cold water failure, the hot water shuts off automatically.