Air source heat pump water heater is a renewable and energy efficient device in the sector of sanitary hot water production. The research focus on the design and building of a data acquisition system comprises of a data logger, power meters, flow meters, temperature sensors, ambient and relative humidity sensor and input pulse adapters to monitor the ASHP water heater performance. All the sensors are accommodated by the U30-NRC data logger and contain digital input pulse adapters to eliminate errors in the measurements. The temperature sensors are installed on the inlet pipe containing a flow meter and the outlet pipe of the ASHP, the outlet pipe from the bottom of the storage tank connected to the inlet of ASHP, the outlet pipe from the storage tank into the building containing a flow meter, the vicinity of both evaporator and expel cold and dehumidify air. The result of a typical weekday shows that the system consumes 5.50 kWh of electrical energy with an average COP of 2.07 and the average volume of water utilized was 318 liters. It was depicted also that the average ambient temperature and relative humidity were 20.9 °C and 43.3 % while, the average power consumption of the ASHP water heater was 1.40 kW.