Shopping for Smart Thermostats
The latest energy-saving devices can talk to your power company — and you
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.
The Superstat thermostat from Honeywell receives pricing signals from the utility — through a meter-mounted wireless transceiver — and turns temperatures up or down in increments set by the homeowner. Available for a monthly fee only through utilities that offer time-of-use pricing.
One development that makes the high price of communicating thermostats more palatable is the trend toward "time-of-use" energy pricing. Some utilities now vary what they charge for electricity throughout the day, based on fluctuations in the demand for power. For instance, Gulf Power Company, which supplies electricity to 370,000 customers in Florida's panhandle, may charge 29 cents per kilowatt-hour on a hot August afternoon, and only 3.5 cents per kilowatt-hour during off-peak hours (9 p.m. to 6 a.m.). Homeowners who subscribe to Gulf's time-of-use pricing program for $4.53 a month are equipped with thermostats that receive a wireless signal from the utility. When the price of electricity is going to peak, the thermostat responds by automatically turning up the A/C temperature (by an amount predetermined by the homeowner) and turning off up to two other noncritical appliances (such as a water heater or a pool pump). The customer reaps the benefits in lower electricity bills. (Setbacks can be overridden manually, if need be.)
This thermostat also displays when peak rates are in effect, so customers can choose to delay such electricity-intensive chores as dish washing and clothes drying. Steve Higginbottom, a Gulf Power spokesman, says customers in the program save an average of 15 percent on their electricity bill. Similar time-of-use experiments are under way in New York, California, Washington, and other states to help homeowners get more control over their energy costs. That's the ultimate in thermostat intelligence?knowing when to flip the switch and when to leave it alone. After all, the most cost-efficient appliance is the one that isn't running.
Wireless thermostats like Carrier's Multi-Stage Programmable ($300) allow you to control temperatures from as many as four different locations, a boon for anyone who wants to ward off the chill of a north-facing room or the heat from a southwestern exposure. Each portable thermostat sends a radio signal to a receiver, which is connected to the heating and cooling system. To prevent thermostat wars between family members, only one person can be in control at a time.
A thermostat doesn't have to be interactive to make a difference in your energy bill. By automatically "setting back" temperatures when the house is unoccupied, programmable thermostats can save on energy costs — as much as 1 percent for every degree of setback over an eight-hour period.
There's just one hitch: You have to take the time to program them. "Some of the first generation of programmables were painful to use," says This Old House plumbing and heating expert Richard Trethewey. "People got fed up. They'd just press the "hold" button and do it manually."
Today's digital thermostats are a different breed. Not only are they easier to set up, with bigger displays and customized options for every day of the week, they've acquired even more energy-saving and consumer-friendly smarts. For instance, there are models that can "learn" how long it takes to heat or cool a house and then how to most efficiently maintain a room's temperature within half a degree of the setpoint. Others automatically change setback times when Daylight Savings kicks in, and automatically switch from heating to cooling. And if there's ever a power outage or the batteries die, they remember and restore all the settings.
To reap the maximum benefit from any of these devices, which range in price from $40 to $300 and up, it has to work in concert with your heating and cooling system. A good first step is to call the local HVAC dealer who sells the furnace, boiler, or heat pump you now own to find out what your options are. If it makes sense to get a high-end programmable, then let the dealer install it or recommend someone who can. These units are not found on home-center shelves, in any case, and an expert installation will help ensure that your thermostat performs at its full potential, delivering all the comfort and energy savings it possibly can.
Carrier's sleek "flush-mount" model ($170) projects from the wall just
1/8 inch (the thickness of two pennies). Like many digital thermostats, it allows seven-days-a-week, four-settings-per-day programming. It also can receive signals from an outdoor sensor and display them on its big, easy-to-read back-lit LCD screen.
Where to Find It
Omnistat RC-90 Single Stage Heat/Cool by HAI
New Orleans, LA
Perfect Climate Comfort Center PC8900 by Honeywell
Golden Valley, MN
GoodCents SELECT Superstat by Honeywell, available only through utilities.
Multi-stage Wireless Residential Thermostat (TSTATC-CPRF010) by Carrier
(TSTATC-CPF701) by Carrier.