Heat Pump Water Heaters (HPWH)
Heat Pump Water Heater (HPWH) is a highly efficient water
heating system that utilizes heat pump technology to heat
potable water rather than air for space conditioning. It is
a system in that most heat pump configurations also require
a back-up heat source such as an electric or gas storage water
heater. At the very least, a tank is needed to store the heated
water. Very high efficiency is obtained because the HPWH extracts,
rather than generates, heat from a medium such as air and
transfers that heat to the water. Although the HPWH offers
the added benefit of air cooling, its primary function is
Despite its energy efficiency, the commercial market for Heat
Pump Water Heaters is very small–perhaps not as large
as 1,000 units/year nationally–compared to approximately
155 thousand water heaters shipped annually to the commercial
are best suited to applications that meet heavy hot water
requirements over long periods of time with electric resistance
water heaters and that require spot cooling or dehumidification.
HPWHs have been used in restaurants and laundromats regardless
of climate. Indoor pools, athletic facilities, hotels and
apartment buildings have also installed HPWHs.
studies done by DOE, it was noted that heat pumps, in general,
are not very efficient at low temperatures– less than
50°F. Additionally, HPWHs require a back-up heat source,
usually expensive electric resistance heating. DOE determined
that HPWHs are only efficient in select regions of the U.S.
and only when compared to electric resistance water heating.
issues with HPWHs concern space limitations and the lack of
a manufacturing, sales and service infrastructure. For maximum
operating efficiency, a HPWH must be surrounded by at least
1,000 cubic feet of air space and installed in locations that
remain between 40° and 90°F year round.
Pump Water Heater