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Heat Pumps Water Heater Systems
Until recently, heat pumps were
merely heating and cooling devices. Now, besides those
traditional uses, heat humps may also provide water heating.
Heat Humps Water Heaters
performance
Heat pumps water heaters consume
electricity, as traditional systems, but they are on average
three times more efficient than common
systems,
expressed by their COP (Coeficient
Of Perfomance), and also by ratings like
SEER and HSPF.
Stand-alone Air Source Heat Pump
Water Heaters
Heat pump water heater systems
can be…
- stand-alone systems or
- integrated water-heating-space-conditioning systems.
Basically, a stand-alone heat
pump water heater is a refrigerator working in reverse: it
pulls heat from the surrounding air, increases its temperature
and damps it into a tank to heat the water.
Integrated water-heating-space-conditioning
systems
You can install an heat pump that
provides both heating, cooling, and water heating.
Such system may involve geothermal heat pumps
or air source heat
pumps. In the second case, since the system drives
heat from the outdoor air (in the winter) or from the indoor
air (in the summer) climate is an important element: air source
water heater pumps work better in a warm climate.
Ground heat pumps and water
heating
Ground heat pumps can be
used to water heating (besides
air conditioning). For water heating, you should add
a small, auxiliary heat exchanger (called a desuperheater) to
the geothermal heat pump. Desuperheaters use superheated
gases from the heat pump's compressor, and pipe it to a storage
water heater tank.
The system is particularly
efficient in hot and moderate weather, when the desuperheater can use the excess heat produced by the heat pump
to heat the water.
The triple-function
geothermal/ground heat pump systems - providing heating,
cooling, and hot water – are becoming increasingly common.
Cost
The cost of a stand alone heat pump water
systems may range $from 600 to over $2000 (more $300 to $700 to
install).
Requirements and drawbacks
Heat pump water heaters do not
operate efficiently in cold climates and cold spaces. Besides,
they cool the spaces they are in, which may also be a
disadvantage, namely in cold climates.
Air source heat pump water
heaters require climates or locations offering adequate
temperatures: 40º/90ºF (4º/32ºC) year-round. They also require
adequate air space (at least 1,000 cubic feet: 28 cubic meters)
around the water heater.
Warranty
Warranties are very variable: they may range
from 1 year to 7 years and vary by parts and manufacturers.
Costs and Payback
Conventional
water heaters demand a lower initial investment, but heat pump water heaters offer lower operating costs (typically a
third). The estimated recovery of the initial investment
ranges from 2 to 5 years, but it depends very much on electricity
prices.
See also:
Basics on Heat Pumps Systems
Ground heat pump systems
Air source
systems
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