• This non-metallic heat exchanger has better corrosion resistance. • The thermal conductivity of this non-metallic material is higher than that of traditional non-metallic heat exchangers. • The heat transfer coefficient of the nonmetal heat exchanger is less than that of the metal heat exchanger. • The heat exchanger in the sewage tank at different depths affects the adhesion rate of stains on the surface of the device, which is mainly caused by the different water flow rates. • Sewage heat recovery system plays an important role in energy saving and environmental protection. Sewage water source heat pump (SWSHP) systems with energy saving and environmental protection advantages have been widely studied, and sewage heat exchangers are an important part of SWSHP systems. Problems such as scale formation, difficulty in cleaning, and rapid decrease of their heat transfer coefficient with time have long been associated with SWSHP systems. With these in mind, in this study, we build a SWSHP system for the recovery of heat from waste using a waste water bath experimental platform, and applied a new, rare earth element (REE) non-metallic immersion sewage heat exchanger, The heat exchanger has heat transfer ability in actual working condition, as well as the operational features of a SWSHP system. From test data, the attenuation of heat transfer and the heat transfer coefficient of the sewage heat exchanger with time were analyzed. An attenuation formula of the heat transfer coefficient was determined using a logistic function. The results show that during 90 days of continuous operation, the surface heat transfer capacity decreased by approximately 7.8%, and the rate of decline over time was much lower than that of traditional heat exchangers. The results show that the system can produce hot water at 40.4–60.6 ℃, and the highest system coefficient of performance (SCOP) of the system is 5.65. Our study shows that varying the depth of immersion of the heat exchanger in the water pool affects the heat transfer ability of the heat exchanger. Results show that when the heat exchanger is closer to the pool surface, water-flushing action is strong. With a long runtime, the heat exchanger’s heat transfer ability has a slower rate of decline over time. Based on the test results, the energy consumption of the system was analyzed, and the energy saved by the continuous operation of the system for one year was determined to be equivalent to that of burning 4.29 × 10 4 kg of standard coal.