Heat Pump Water Heater-Residential Integrated Units
Electric Water Heater: Heat Pump vs. Electric Resistance
Heat pump water heaters (HPWHs) use a heat pump refrigeration cycle to remove heat from the surrounding air and transfer that heat at a higher temperature into the integral hot water storage tank. “Integrated Units” means that the heat pump and water heater tank are pre-manufactured as a single piece of equipment.
Synopsis:
Heat pump water heaters (HPWHs) use electricity to transfer heat from the ambient air to stored water, as opposed to using electric resistance heat or natural gas for water heating. This enables them to be two to three times more energy efficient than conventional electric resistance water heaters (FEMP Promising Technologies List).
To move the heat, heat pumps work like a refrigerator in reverse. While a refrigerator pulls heat from inside a box and dumps it into the surrounding room, a stand-alone air-source heat pump water heater pulls heat from the surrounding air and dumps it — at a higher temperature — into a tank to heat water.
Water heating accounts for 3,030 kWh annually or 15%–20% percent of electric energy use in homes with electric water heat ( Ecotope, 04/28/2014). New HPWHs offer an energy-savings potential of 50% or more. The cost of this product is approximately $600–$1,300 above the installed cost of a conventional 50-gallon electric water heater, so the simple payback of a HPWH is expected to be in the range of 5–16 years.
HPWHs work best in locations that remain between 40⁰ to 90⁰F year-round and provide at least 1,000 cubic feet of air volume around the water heater. Cool exhaust air can be exhausted to the room or outdoors. Locating the HPWH in an attached garage is ideal, but when installed in an unconditioned space, the reduced temperature in the winter will reduce performance. Heat extracted by the HPWH from a conditioned space in the heating season will require more heat input from the existing space heating system. In an electric resistance heated house, heating the water with heat from the conditioned space provides no energy savings as it results in a water heating COP less than 1.0.
Energy Savings: 50%
Energy Savings Rating: Approved Measure
What's this?
| Level | Status | Description |
| 1 | Concept not validated | Claims of energy savings may not be credible due to lack of documentation or validation by unbiased experts. |
| 2 | Concept validated: | An unbiased expert has validated efficiency concepts through technical review and calculations based on engineering principles. |
| 3 | Limited assessment | An unbiased expert has measured technology characteristics and factors of energy use through one or more tests in typical applications with a clear baseline. |
| 4 | Extensive assessment | Additional testing in relevant applications and environments has increased knowledge of performance across a broad range of products, applications, and system conditions. |
| 5 | Comprehensive analysis | Results of lab and field tests have been used to develop methods for reliable prediction of performance across the range of intended applications. |
| 6 | Approved measure | Protocols for technology application are established and approved. |
Simple Payback is one tool used to estimate the cost-effectiveness of a proposed investment, such as the investment in an energy efficient technology. Simple payback indicates how many years it will take for the initial investment to "pay itself back." The basic formula for calculating a simple payback is:
Simple Payback = Incremental First Cost / Annual Savings
The Incremental Cost is determined by subtracting the Baseline First Cost from the Measure First Cost.
For New Construction, the Baseline First Cost is the cost to purchase the standard practice technology. The Measure First Cost is the cost of the alternative, more energy efficienct technology. Installation costs are not included, as it is assumed that installation costs are approximately the same for the Baseline and the Emerging Technology.
For Retrofit scenarios, the Baseline First Cost is $0, since the baseline scenario is to leave the existing equipment in place. The Emerging Technology First Cost is the Measure First Cost plus Installation Cost (the cost of the replacement technology, plus the labor cost to install it). Retrofit scenarios generally have a higher First Cost and longer Simple Paybacks than New Construction scenarios.
Simple Paybacks are called "simple" because they do not include details such as the time value of money or inflation, and often do not include operations and maintenance (O&M) costs or end-of-life disposal costs. However, they can still provide a powerful tool for a quick assessment of a proposed measure. These paybacks are rough estimates based upon best available data, and should be treated with caution. For major financial decisions, it is suggested that a full Lifecycle Cost Analysis be performed which includes the unique details of your situation.
The energy savings estimates are based upon an electric rate of $.09/kWh, and are calculated by comparing the range of estimated energy savings to the baseline energy use. For most technologies, this results in "Typical," "Fast" and "Slow" payback estimates, corresponding with the "Typical," "High" and "Low" estimates of energy savings, respectively.
Status:
Next Steps based on Identification Stage (Stage Gate 1): Accept