Air-to-water heat pumps have generated a lot of excitement for their enormous retrofit potential. This case study details one home’s retrofit to an AWHP system, which was developed by hydronics experts to be simple and repeatable. The project encompassed distribution systems, domestic hot water and backup heat, as well as a ventilation system upgrade from exhaust-only to high-efficiency fresh air (balanced) ventilation. We’ll present full project costs, before/after breakdown of energy models/costs, details on the beyond-energy motivations and benefits gained by the homeowners, and we’ll share extensive data from this project’s comprehensive monitoring systems along with two other installations in Vermont. We’ll summarize lessons learned and the limitations and challenges in designing for air-to-water retrofittability. There will be ample time for lively Q&A.