An air-source heat pump (ASHP) heating system was used to improve the performance of the heating system in an old community of Handan and field test was conducted during the heating season of 2019–2020. In addition

the long-term operating performance was analyzed and the operating characteristics of the system under four different working conditions were compared based on the air temperature and humidity outdoors

temperature and flow rate of the supply and return water

the power consumption

and the practical regulation mode with variable water temperature. The results show that for the energy consumption of the entire heating period

a staged variable water temperature adjustment is beneficial for promoting the energy-saving rate of the air-source heat pump. The high outdoor relative humidity in Handan during winter can easily lead to poor operation of the air source heat pumps and an insufficient heat supply. At this time

the use of a time-varying water temperature adjustment is more beneficial than the staged variable water temperature regulation for improving the system operation. The COP of the second stage of the heating period increased from 1.63 to 1.76 in the third stage

which is an increase of 8%.