The "Drop-In" Residential Heat Pump Water Heater
A market-driven solution to efficient electric heating, The
Problem: How to Convince Consumers to Save Energy in Water Heating
About half of all
domestic water heating is done with electric resistance storage water heaters. The most efficient resistance water heater
has an energy factor (EF) of 0.95, only 5% below the maximum efficiency possible for that type of water heater. Yet by using
electricity to "pump heat" from the surrounding space, the residential heat pump water heater (HPWH) can attain much higher
efficiencies, reducing the electricity needed for water heating by at least half.
Despite such high efficiencies, today's U.S. market
for residential HPWHs is small and stagnant (less than 2,000 units/year) and is served by only two or three manufacturers.
Why has the HPWH market remained small?
conducted by DOE and others point to a number of issues:
Economics — High first cost, leading to long payback time.
Reliability — Failures of early models created a poor reputation for the HPWH.
Maintenance — Service infrastructure lacking; specialized training and familiarity are required.
Installation — HPWHs not well-suited to universal installation; easier to replace like-for-like.
Awareness — Customers not aware of HPWH benefits; few have even seen one.
The Solution: The "Drop-in" HPWH
Building from a strong understanding of these technical and market issues, Enviromaster International
(EMI) and Arthur D. Little, with support from the DOE ENERGY STAR Program through Oak Ridge National Laboratory, are developing
a unique "market-optimized" ambient-air HPWH aimed at the large electric water heater replacement market.
A full "drop-in" replacement for 50- or 80-gallon electric water heater
— same footprint as the original water heater, an identical electrical hookup, no need for additional plumbing, and
no condensate drain required
Uses refrigeration compressor — robust, proven,
inexpensive, small, yet with sufficient capacity for meeting most water heating demands
Uses no water pumps
Employs a conventional hot water tank; no additional penetrations
Will work anywhere that a conventional resistance water heater will work — basements, closets,
garages, conditioned spaces
Designed for installation by plumber — no additional