Thermostats get smarter

Managing today's rising utility costs with a dinosaur thermostat from the 1950s can be a money-losing proposition. The standard dial thermostat lasts forever, but its shortcoming is lack of intelligence. A smarter thermostat can cut your heating and air-conditioning costs up to 33 percent, according to manufacturers.

Programmable digital thermostats automatically control your home's heating and cooling. These compact wall-mounted appliances utilize a microcomputer, a liquid crystal display, and a small keypad for programming.

The thermostat usually divides the day into four periods. You program times (8-5:30, for example) and a temperature for each period.

Here's an example for winter heating in a cold climate. Overnight, the furnace is set to 60° or lower, the energy-savings temperature. Half an hour before the alarm clock rings, the thermostat triggers an increase in heat to the comfort temperature - say 70° (warm clothes, down comforters, and other common-sense measures let you live comfortably with significantly lower temperatures).

When you leave, the thermostat automatically resets to save energy. Half an hour before you return, the thermostat goes back to comfort level. When your schedule changes temporarily, you can manually adjust the thermostat, then return to the program at the touch of a button. Many models offer a "vacation mode" that will maintain your home at a constant temperature for weeks.

In hot weather, the thermostat can control whole-house air-conditioning in a similar way, although you may choose to have only one cooling cycle per day, to bring down the temperature when the house is hottest and you're home at day's end.

Some thermostats self-adjust for seasonal changes using an internal calendar programmed at the factory. Most models feature battery backup so you won't have to reprogram if household power is lost. Batteries commonly last about two years, but manufacturers recommend that you replace them annually.

You can easily install a programmable thermostat yourself. Most are designed as replacements, so they will cover the hole left by your old thermostat. - Conrad Weiss