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TECHNOLOGY AND YOU

New heat pumps provide comfort and savings

Q: I have an old heat pump. I often feel chilly and I think my heating bills are high. Do new heat pumps produce more comfortable heat and does it ever make economic sense to replace an old, but still working one? - M. K.

A: The answer to both your questions is yes. There have been significant improvements in the comfort (no more chilly feeling), efficiency and sound level of heat pumps. My own house has an eight-year-old heat pump.

It sometimes makes economic sense to replace your old heat pump even though it still works. Installing a new super-efficient heat pump can cut your heating bills by 30 to 40 percent. The best ones provide $3 worth of heat for each $1 of electricity used. Have your heat pump dealer do a computerized payback analysis for you. This is usually a free service. Your local electric cooperative's energy advisor can also give you an estimate of what you can expect to save.

A new heat pump will also yield a similar savings when air-conditioning in the summer. With a new heat pump you can help your electric cooperative keep your long-term electricity rates reasonable because a heat pump reduces the expensive peak electricity demand each summer.

New heat pump designs, with two heating and cooling output levels, provide the highest overall efficiency and the best comfort. These heat pumps run on the super-efficient, low-output level the majority of the time. When the weather gets severely cold or hot, they automatically kick into the high-output mode to keep your house comfortable.

On the low-heat output level, low electricity usage level, the heat pump runs for longer periods of time. This provides more even room temperatures with fewer chilly drafts in winter and better humidity control in the summer. If you plan to install a good-quality central air cleaner, these types of systems are ideal.

A "smart" variable-speed indoor blower motor is also recommended for all two-heat level models. When the blower first comes on, the speed ramps up slowly to minimize initial chilly drafts. These special blower motors also use about 60 percent less electricity. This can save another $100 per year for people with allergies who use continuous air circulation.

One two-output level design uses one small and one large compressor inside the standard outdoor unit. During mild weather, it starts on the smaller, low-output compressor. If this cannot keep your house adequately warm during severe weather, the small one automatically switches off and the large compressor starts. The same happens in the summer when it switches to the air-conditioning mode.

The other super-efficient two-output level design uses a single two-speed compressor. It has a special two-speed motor and electronic controls that determine the optimum speed for comfort and efficiency. This design is a little less expensive than the two-compressor design, but there are some slight performance compromises to accommodate the changing speeds.

If your budget only allows for a single-output level heat pump, you will still realize dramatically improved comfort and efficiency. A single-speed model with a reliable scroll compressor

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.

Copyright 1998 James Dulley

18 ILLINOIS COUNTRY LIVING MARCH 1998

is a good choice. A scroll compressor has only a few moving parts and actually improves its efficiency as it wears over time. Also, look for sound-reducing features like laminated steel/rubber compressor pads.

For the ultimate comfort, have a "smart backup heat" control kit installed. Some are available to fit on existing heat pump indoor air handlers. These kits have a computer brain to bring on just enough backup electric heat to warm the register outlet air to two degrees above your skin temperature. This is enough to make the air blowing out feel warm.

To compare efficiencies of various heat pumps, use the Heating Season Performance Factor (HSPF) for heating and Seasonal Energy Efficiency Ratio (SEER) for cooling. These figures provide a true overall comparison. You may also see COP (coefficient of performance) ratings. These compare the heat pumps' steady-state operating efficiencies, but do not take the start-up and other normal variations into account.

Write for Utility Bills Update No. 446 — buyer's guide of the 15 most efficient, comfortable heat pumps, output levels, compressor types, efficiencies, blower motors and a savings/payback chart. Please include $2 (with checks payable to Jim Dulley) and a business-size SASE. Mail to: Jim Dulley, Illinois Country Living, P.O. Box 3787, Springfield, IL 62708. For instant download, go to http:// www.dulley.com.

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