Question: Our heating and air-conditioning bills are busting the budget. I have heard about Earth-friendly geothermal heat pumps that can cut our bills in half. What are they, and are they good for any home?
Answer: A geothermal heat pump is an ideal year-round system for almost any home. Basically, it draws "free" extra heating and air-conditioning capacity from the ground. Over its life, such a pump can save many thousands of dollars.
For example, in the winter, for each $1 on your utility bills, you get $4 worth of heat ($3 free from the Earth). These systems also eliminate that "chilly" air feeling common to regular heat pumps in the winter.
If you have an old central air conditioner, installing the most efficient geothermal heat pump can reduce your cooling bills by two-thirds. Even more important is the superior dehumidification (for allergy sufferers) and steady cooling, even on the hottest summer afternoons.
Many geothermal heat pumps use a water / antifreeze-filled plastic pipe loop buried in the yard. This earth loop is used instead of the typical noisy outdoor condenser fan unit. This results in a quiet system (all indoors) with less risk of damage and maintenance problems.
Geothermal heat pumps attain high efficiency because the ground temperature stays fairly constant year-round. It is much easier in the winter to "pump" heat from the warm ground at 50 degrees than from the frigid outdoor air.
In the summer, the situation is reversed. It is much easier to pump heat from inside your house to the cooler 50-degree ground than to the oven-like outdoor afternoon air. For an additional savings, this wasted indoor heat can be diverted to your water heater for free hot water all summer.
There are many designs of geothermal heat pumps to choose from, depending on your budget, yard and specific needs. The ground pipes are normally buried in a very narrow trench. If your yard is small, the pipes can be placed in vertical holes drilled deep into the ground. Ponds or wells are also used.
The best geothermal heat pumps (for year-round comfort and savings) use multilevel heating and cooling outputs. These models use either two small compressors or a single two-speed one. They continually adjust the heating and cooling outputs to match the varying comfort requirements of your house.
Another, simplified but highly efficient, single-level design uses direct exchange (DX). Instead of using plastic pipes buried in your yard, much shorter, tiny copper pipes are used. These are ideal for smaller yards.
Write for (or download, http://www.dulley.com) Update Bulletin No. 793, a buyer's guide of 12 single and multilevel geothermal heat pumps, efficiencies, outputs, features and a fuel cost comparison chart. Please include $3 and a business-size self-addressed envelope, and mail to James Dulley, Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, OH 45244.
Letters and questions to James Dulley, a Cincinnati-based engineering consultant, may be sent to James Dulley, Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, OH 45244.