New Efficient Heat Pumps

Q — Our heat pump is about 15 years old. It blows out chilly air each
time it starts and it is noisy. What is new in heat pumps and are new ones more
efficient and comfortable? How much can we expect to save on our electric bills?-Meg
S.

A–If your heat pump is
15 years old, you will be amazed at the improved comfort with a new system (both
outdoor compressor and indoor blower units). I know because I just replaced an
old heat pump with a new system that uses new ozone-friendly R-410A refrigerant
instead of freon.

Since a heat pump is used year-round, the utility bill
savings often justify replacing your old unit now, even though it is still running.
Depending on the efficiency of your old heat pump, you can enjoy significant savings
on your electric bills.

The heating efficiency of a heat pump is called its
Heating Seasonal Performance Factor (HSPF) and the cooling efficiency is called
Seasonal Energy Efficiency Ratio (SEER). The new models, like the one I installed,
have HSPFs of about 8 and SEERs of 13. The contractor’s computerized analysis
shows that it will use about 41% less electricity than my 17-year-old one.

You have many new efficient heat pump options from
which to choose, depending on your comfort needs, your budget, and your interest
in the environment. Whatever type you select, make sure to have the indoor coil
(the blower unit in your basement or utility room) matched to the outdoor compressor
unit. Without it, efficiency will be sacrificed and it may not adequately dehumidify
your house as it cools in the summer.

The newest models use R-410A refrigerant instead of
freon, which attacks the ozone layer. These R-410A compressors (usually scroll
designs) run at higher internal pressures, so heavy-duty compressor parts and
coil materials are required.

If your budget is not tight and you want the best comfort
and absolute highest efficiency, select a two-level output heat pump. These models
use one of two designs: 1) two separate compressors in the outdoor unit or 2)
a single two-speed compressor motor. Both designs run on the low-output level
the majority of the time.

By having a low-electricity-usage, low-output (heating
or cooling) mode, the heat pump will not start and stop as often. This greatly
improves the comfort, maintains even room temperatures, and is beneficial for
allergy sufferers who need effective air cleaning. The entire unit, whether heating
or cooling, operates super efficiently when it is in the low-output level mode.

For budget concerns, most homeowners will probably
install a single-level output heat pump model. Most models use a simple scroll
compressor with either freon or new R-410A. An optional variable-speed blower
motor can also be used for better comfort. With this optional motor, the efficiencies
are usually about one point higher.

Using a variable-speed blower motor coupled with a
special new temperature/ humidity thermostat (called a thermidistat) allows you
to adjust the humidity and temperature independently. The smart variable-speed
blowers use only about 30% as much electricity as a standard blower motor.

Don’t forget to also have your duct work inspected,
tested, and replaced if necessary, in order to gain optimal performance and savings.