Heat pump water heaters for retrofits with constraints

August 19, 2026 by Dani Ball and Andrew Kotila

Domestic water heating is a crucial component of residential electrification, especially with the growing suite of heat pump water heaters (HPWHs), which heat water more efficiently than standard water heaters.

Unitary 240V HPWHs are a good fit for many home types in Minnesota. However, in space– and electrically-constrained residences such as multifamily apartments and manufactured homes, there are hurdles to installing these water heaters.

This study, conducted in partnership with Center for Energy and Environment and New Buildings Institute, will chart a practical path to electrifying domestic water heating in multifamily and manufactured homes by identifying the installation barriers, opportunities, and performance of HPWHs designed for constrained conditions. These solutions include split-system heat pump water heaters, which locate the hot water tank indoors and the compressor and fan outdoors.

Our team plans to measure split-system heat pump water heater performance in six to eight multifamily units across at least two apartment buildings, plus two manufactured homes, in Minnesota. The homes will receive free installation of a new split-system heat pump water heater. Measured results will provide data on the cost effectiveness and cold weather efficiency of these products to inform future Minnesota energy conservation programs.

Benefits of Participating

Selected participants will receive, at no cost:

  • A new heat pump water heater installed in your dwelling unit. 
  • A site-specific report summarizing findings, including estimated energy usage, room temperature and humidity impacts, and hot water usage data. 
  • An assessment process designed to have minimal impact on your home's day-to-day activity. All site visits, measurements, and temporary installations of data collection and monitoring equipment will be scheduled, coordinated, and conducted in a way to minimize disruption to your household.

Eligibility

To be eligible for this study, all participants must:

  • Live year-round in an apartment or manufactured home located in Minnesota.
  • Have an existing gas or electric water heater that is located in a utility closet or utility room in the home or apartment unit. (Multifamily buildings with a central water heater shared by multiple apartments are not a good fit for this study).
  • Allow Slipstream staff and contractors onsite to complete the water heater installation and monitoring equipment setup, as well as a limited number of follow-up visits as needed.
  • Complete short surveys on comfort, noise, performance, and related questions.

For multifamily facilities, both the landlord and the apartment tenant must mutually agree to participate. It would be ideal if multiple units in the same apartment building would participate at the same time.

Interested in learning more or participating?

Please fill out this intake form

If you have questions, please reach out to the Project Manager, Andrew Kotila.

This research builds on a prior study on 120-volt HPWHs conducted by Slipstream and co-funded by Xcel Energy, Focus on Energy, ComEd, and Consumers Energy.

This research was made possible by a grant from the Minnesota Department of Commerce, Division of Energy Resources through the Conservation Applied Research and Development (CARD) program, which is funded by Minnesota ratepayers.