Field monitoring data on a residential exhaust air heat pump system (air to air heat pump)
Figure 1 (Fig1_Measurement_Setup) shows a hydraulic illustration of the investigated exhaust air heat pump (EHA-HP) and the position of the installed sensors. Air temperature and humidity on all four sides of the unit (outdoor air, extract air coming from the building, supply air to the building and exhaust air leaving the house) and electrical power consumption of the unit (compressor and ventilators) were measured and logged. The measurement period was 55 winter days with an interval of 1 second. In addition, the dynamic pressure difference (as an indication of the air volume rate) on the exhaust side was logged during the measurement period. Finally, the air volume rates of the unit at different ventilation levels was measured using Constant injection tracer gas method. Figure 2 (Fig2_summary_Vol_rates) summarizes the measured air volume rates and ventilators’ powers usage in different levels. The measurements were conducted in a KfW 55 efficient house with a living area of 235 m² near Stuttgart, Germany. The EHA-HP was installed in an air based hybrid heating system as the central heating source of the building. Figure 3 (Fig3_Applied_Sensors) gives an overview of the applied measurement methods and used sensors. Logging and conversion of signals were conducted using a modular I/O system; the fieldbus controller Ethernet 750-881 from WAGO Kontakttechnik.