What Is It?

A thermostat, the unassuming box on the wall, pretty much controls the comfort of your family. It is a temperature-sensitive switch that controls a space conditioning unit or system, such as a furnace, air conditioner, or both. When the indoor temperature drops below or rises above the thermostat setting, the switch moves to the "on" position, and your furnace or air conditioner runs to warm or cool the house air to the setting you selected for your family's comfort. A thermostat, in its simplest form, must be manually adjusted to change the indoor air temperature.

Smart Use

Want to save energy? During the winter, set the thermostat to 68°F (20°C) when you're at home and awake; lower it when you're asleep or out of the house. This strategy is effective and inexpensive if you are willing to adjust the thermostat by hand and wake up in a chilly house. In the summer, you can follow the same strategy with central air conditioning, too, by keeping your house warmer than normal when you are away, and lowering the thermostat setting to 78°F (26°C) only when you are at home and need cooling.

Types of Programmable Thermostats

Most range in price from $30 to $100; occupancy and light sensing thermostats cost around $200.

1) Electromechanical (EM) thermostats are best suited for people with regular schedules. They are also usually the easiest devices to operate and typically have manual controls such as movable tabs to set a rotary timer and sliding levers for night and day temperature settings. These thermostats work with most conventional heating and cooling systems, except heat pumps. EM controls have limited flexibility and - for the most part - can store only the same settings for each day.

2) Digital thermostats are identified by their LED or LCD digital readout and data entry pads or buttons. They offer the widest range of features and flexibility, they can be used with most heating and cooling systems, they provide precise temperature control, and they permit custom scheduling. Programming some models can be fairly complicated, so make sure you are comfortable with the functions and operation of the thermostat you choose.

3) Hybrid systems combine the technology of digital controls with manual slides and knobs to simplify use and maintain flexibility. Hybrid models are available for most systems, including heat pumps.

4) Occupancy thermostats are best suited for spaces that remain unoccupied for long periods of time. These units offer the ultimate in simplicity, but lack flexibility. They maintain the setback temperature until someone presses a button to call for heating or cooling. They do not rely on the time of day. The ensuing preset "comfort period" lasts from 30 minutes to 12 hours, depending on how you've set the thermostat. Then, the temperature returns to the setback level.

5) Light sensing heat thermostats are designed primarily for stores and offices where occupancy determines lighting requirements - and therefore heating requirements. They rely on the lighting level preset by the owner to activate heating systems. When lighting is reduced, a photocell inside the thermostat senses unoccupied conditions and allows space temperatures to fall 10° below the occupied temperature setting. When lighting levels increase to normal, temperatures automatically adjust to comfort conditions. These units do not require batteries or programming and reset themselves after power failures.

The best thermostat for you will depend on your life style and comfort level in varying house temperatures. While automatic and programmable thermostats save energy, a manual unit can be equally effective if you diligently regulate its setting (and if you don't mind a chilly house on winter mornings). Should choose an automatic thermostat, you can set it to raise the temperature before you wake up and spare you some discomfort. It will also perform consistently and dependably to keep your house at comfortable temperatures during the summer heat, as well.