Smart Thermostats
Photo: Darrin Haddad
Pop off the cover of a typical thermostat and you'll find little more than a temperature-sensitive metal coil and a dollop of mercury sloshing around in a glass tube. Cheap and rugged, as switches go, but not exactly the smartest, most energy-saving device you can put in charge of a furnace or boiler. The introduction of so-called setback thermostats improved matters somewhat: They got rid of the toxic mercury and the coil, but enabled homeowners to do little more than automatically adjust the temperature at night or when a house is unoccupied.

Now meet the real geniuses: interactive "communicating" thermostats. They not only have the ability to talk to each other (and thereby reduce unnecessary on/off cycling by the heating and cooling system), they can hop aboard the Internet to send you a distress call or check the latest gas or electricity prices with your power company and adjust the house's energy consumption accordingly. Some even take phoned-in instructions, a useful feature for when you want to alert your furnace to start warming up the house before you get home. If these thermostats had any more brainpower, they'd be picking up the mail and watering the plants.

Smart doesn't come cheap, however. You'll pay anywhere from $150 to $400 or more for one of these high-end electronic Einsteins. And because installation is not as simple as attaching a couple of wires, most manufacturers recommend that you have a trained electrician or HVAC contractor put in the necessary hardware. This includes an electronic "gateway," a digital transfer station that allows the thermostat to send and receive data over a phone line, cable, or wireless transmitter. A gateway can be the phone, a computer, or a central control unit that also operates other home automation systems. Depending on the type of gateway device required and how difficult it is to run the necessary low-voltage wires to your heating and cooling equipment, installation adds another $300 to $1,000 to the cost of owning a state-of-the-art temperature switch. Once it's "networked," though, your thermostat is never more than the push of a button or click of a mouse away.

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