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?
Assessments
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.
Design
Features
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 skills needed.