SIR24-P is a presence detector designed for automatic ventilation control of HVAC systems. It uses infrared light. The detector has a potential-free change-over relay for activation/deactivation of for instance a fan-coil controller. It saves money and gives higher comfort in premises requiring forced ventilation for shorter periods of time, such as conference rooms, assembly-halls etc. The unit can be wall or corner mounted with a 110°, 15m detection range.