Wastewater-source heat pump (WWSHP) applications to wastewater collection systems provide an attractive option for recovery of thermal energy. Although the idea is not new, there are few if any existing studies that talk about how the WWSHP location relative to the collection system influences efficiency. We used a wastewater collection system model and cost-benefit analysis to examine the payback time for a WWSHP relative to a conventional hot water boiler. The best location for WWSHP implementation depends on design capacity and collection system size, and the payback time could be as low as 3 years. There is a threshold of design capacity (160 kW) in the range of sizes that we investigated, and hourly variations leading to a higher electricity price could lead to a longer payback time. However, that threshold should increase and the payback time may decrease (<2 years) if larger sizes are included in the investigation.

废水收集系统中的废水源热泵（WWSHP）应用为热能的回收提供了一个有吸引力的选择。尽管这个想法并不新鲜，但是很少有关于WWSHP相对于收集系统的位置如何影响效率的现有研究。我们使用废水收集系统模型和成本效益分析来检查WWSHP相对于传统热水锅炉的投资回收期。WWSHP实施的最佳位置取决于设计能力和收集系统的大小，投资回收期可短至3年。在我们调查的尺寸范围内，设计容量存在一个阈值（160 kW），并且每小时变化会导致更高的电价，从而可能导致更长的投资回收期。然而，