Today's Technology and you

Today's
TECHNOLOGY AND YOU

Heat pumps are a year-round energy saver

New heat pumps can cut utility bills in half

Q:Dear Jim: Our heat pump is about 15 years old. It blows out chilly air each time it starts and 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: Dear Meg: 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 in my home with an entirely new system that uses new ozone-friendly R410A 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, it is not unreasonable to expect an annual savings as high as 50 percent on your heating and cooling 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 HSPF's of about 8 and SEER'S of 13. The contractor's computerized analysis shows that it will use about 41 percent less electricity than my 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 R410A refrigerant instead of freon which attacks the ozone layer. These R410A compressors (usually scroll designs) run at higher internal pressures, so heavy-duty compressor parts and coil materials are required. This improves overall reliability and the extra mass of the components reduces the noise level and lowers its tone.

If your budget is not tight and you want the best comfort and absolute highest efficiency, select a two-

James Dulley is a mechanical engineer who writes on a wide variety of energy and utility topics. His column appears in a large number of daily newspapers.

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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 much 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.

Another comfort and efficiency advantage of two-level models is the indoor variable-speed blower motor that they use. These special motors automatically fine-tune the air flow for the best comfort, efficiency and quiet operation. Most have a slow "ramp-up speed" start feature. This is quieter and reduces that initial blast of chilly air from the registers whenever the heat pump kicks on.

For budget concerns, most homeowners will probably install a single-level output heat pump model like I have. Most models use a simple scroll compressor with either freon or new R410A. An optional variable-speed blower motor can also be used with these models 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 percent as much electricity as a standard blower motor. Over an entire year, this results in a substantial electricity savings.

A thermidistat is particularly effective for savings in the summer because you can set your thermostat a degree or two higher without sacrificing comfort. For example, if your house is too humid, the thermidistat will select a blower speed for extra dehumidification with little cooling so the house is not overcooled.

The outdoor compressor unit on the new models is sometimes slightly larger than the old one (to accommodate the greater condenser coil area), but most should fit on the same concrete pad without modification. The new indoor blower units should be about the same size as your old one.

"Write for (instantly download - www.dulley.com) Utility Bills Update No. 824 - buyer's guide of the 14 most efficient, comfortable heat pumps listing output levels, efficiency, size, blower type, comfort features, and a savings/payback chart. Please include $3.00 and a business-size SASE. James Dulley, Publication Name, P.O. Box 54987, Cincinnati, OH 45254.

MARCH 2001 • ILLINOIS COUNTRY LIVING 19