120V HPWH Research

Completed Pilot Programs and Demo Projects 120V HPWH Field Study

About the Demonstration Project

Heat Pump Water Heaters (HPWHs) are a promising technology for energy-efficient residential water heating. HPWHs use heat pump technology to heat water more efficiently than electric resistance and gas- or propane-fired water heaters. However, traditional HPWHs require a dedicated 240V circuit, reducing their cost-effectiveness as an electrification solution if major electrical upgrades are necessary. To address this, manufacturers released 120V HPWH models that plug into a standard wall outlet. These units avoid electrical upgrades, but heat water more slowly.

The first phase of this research (2022) was comprised of market research and modeling of the potential for 120V HPWHs in Midwest homes. The study found that 120V HPWHs can provide sufficient hot water for residents with typical hot water usage. However, interviews with plumbers, distributors, and retailers indicated they would be unlikely to sell the product without validation of 120V HPWHs’ high performance in cold climates.

In the second phase of this research (2024), Focus on Energy conducted a field study in Wisconsin in partnership with utilities in other Midwestern states to assess cold climate performance for 120V HPWHs. The field study outlined market potential and savings opportunities of 120V HPWHs in Wisconsin by evaluating the performance of the units in real homes. The field study final report provides recommendations for programs on the best applications of 120V HPWH units, unit installation guidelines and best practices, interview and survey results from installers and consumers, and quantitative analyses of unit effectiveness and efficiency.

As of March 2025, 120V HPWHs are not yet available in the Midwest. However, this research project demonstrated that 120V HPWHs are feasible in Wisconsin climate zones and will provide benefits to utility customers. As a result of the research, manufacturers have stated that they will evaluate deployment of these models into the Midwest.

Timeline: May 2022 - December 2024
Customer Segment: Single-family residential

Demonstration Project Objectives

Determine household types and water heating demands best suited for a 120V HPWH.
Determine best practices for 120V HPWH sizing and installation. Outline any field limitations of the technology, as well as supply chain perceptions that could impact market adoption rates.
Understand the perspective of installers, manufacturers, and consumers through surveys and interviews.
Monitor field performance and analyze data to characterize predictors of hot water availability, quantify relationships between groundwater temperatures, air temperatures, consumption, and efficiency, and calculate retrofit and operating cost impacts.

Lessons Learned

In the first phase of the project, the research team completed market research and modeled 120V HPWH performance under several water usage patterns. Results from this phase of the project included the following:

Equipment Performance:
- 120V HPWHs can supply enough water to satisfy a four to six occupant single family home in Wisconsin and can accommodate consecutive hours of 20-gallon hot water draws.

In the second and most recent phase of the project, the research team installed and monitored 120V HPWHs in 27 single-family Midwestern homes. Results and recommendations from this phase of the project included the following:

Program Design:

120V HPWHs easily replace natural gas units when space is not constrained, and an outlet is present, such as in many Midwest basements. Utilities should incorporate 120V HPWHs into energy efficiency programs as a cost-saving measure to switch from natural gas and propane water heaters.
Utilities should leverage midstream programs and distributor relationships to ensure installers have access to these units at the time of unit replacement.
Utility Trade Allies should have access to educational materials and training on best practices for installation.

Overall Satisfaction:

Participants were quite satisfied with their 120V HPWH units.
The ideal customer for a 120V unit is a household with 4 or less occupants who consume an average amount of water, who currently have a propane or natural gas heater, and who have an electrical setup that accommodates the unit.

Additional conclusions and recommendations regarding installation best practices, unit availability, water consumption and runouts, energy use and efficiency, and retrofit and operating costs can be found in the Phase 2 Final Report linked below.

In the first phase of this project, the research team conducted energy modeling, cost analysis, secondary data analysis, and supply chain research to determine the best applications for 120V HPWHs in Wisconsin. Results from this phase of the project can be found in the Phase 1 Final Report below.

Learn More

Research and Modeling Report: 120V HPWH Phase 2 Final Report
Field Study Report: 120V HPWH Phase 1 Final Report

Questions?

For more information about this study, email FutureFocus@Focusonenergy.com.