Heat recovery devices, namely, solid-liquid separators for the mechanical separation of solid matter from a flow of wastewater for further recovery of energy; wastewater recovery systems for use in heating and cooling systems, comprising solid-liquid separators, wastewater tanks, pumps, heat exchangers, heat pumps, and domestic water storage tanks; wastewater-source heat pump water heaters; hot water heaters; water heaters for domestic purposes; heat regenerators, namely, regenerative heat ex...