The Danfoss AFP differential pressure controller is a self-acting control device designed to maintain a constant differential pressure in heating, cooling and air-conditioning systems. It operates without any external energy supply – control is provided solely by the pressure of the medium itself. The device effectively eliminates hydraulic instabilities caused by variable flow rates in branched systems.

The controller body is made of ductile cast iron with corrosion-resistant internal components, while the diaphragm senses the differential pressure via an impulse line. The required differential pressure setpoint is adjusted manually on the controller scale without the need for tools. The AFP controller is typically used in residential and office buildings, industrial facilities, and wherever branched heating or cooling circuits need to be hydraulically balanced.