Don Vandervort, Head Homeboy, has written more than 30 DIY home improvement books, been a segment host on HGTV, served as MSN.com's home improvement expert and written countless magazine articles.
Beyond basic shelter, one of the most important jobs of a house is to provide a comfortable environment. But, because the human body is highly sensitive to heat gain and heat loss, comfort can be elusive. In the quest to capture it, we fit houses with heating and cooling systems, insulation, efficient windows, weatherstripping, ventilation, and other features meant to control unwanted heat loss and heat gain.
The thermostat was invented in the early 17th century by a Dutch man, Cornelis Drebbel, who placed a float inside a mercury thermometer and connected that apparatus to a damper cover on a furnace. When the mercury climbed to a certain level, the float caused the damper to close. Today’s thermostats do fundamentally the same thing: They connect room temperature to the output of a heating or cooling system.
Essentially a heat-activated switch, a thermostat has a temperature sensor that causes the switch to open or close, completing or interrupting an electrical circuit that runs the house’s heating or cooling system. Most residential models do this with a low-voltage circuit.
To do its job properly, a thermostat should eliminate broad swings in room temperature. During the heating season, room temperature drops to a low point right before the heat goes on and reaches a high just after the heat goes off. According to researchers, the key to comfort is to maintain room temperatures within a 2 degree Fahrenheit swing. Within that “comfort window,” people don't notice a variation in temperature.
Making a choice Unless you have a multiple-stage system that requires a particular type of thermostat, choice usually boils down to personal preference, which is generally a dynamic of features and price. People who are techno-phobic often prefer the simplicity of a conventional electromechanical model. Those who are interested in more control and potential energy savings opt for an electronic type.
Most electronic thermostats cost more than electromechanical types. For example, a professionally installed Honeywell T-87 Round thermostat may run about $40. A high-end electronic model can cost up to about $200 installed. You can, however, buy an electronic thermostat for as little as $40.
Why we like it:
* Touchscreen interface • Easy to read • 7-day programmable
Though all electronic thermostats may look alike, they’re not. If one is considerably cheaper than another, there is probably a reason for the price difference. Some low-priced ones may not be able to maintain a narrow “comfort window.” Others may not adequately anticipate at what point the furnace must turn off, thereby wasting residual heat and overshooting the desired room temperature. Also, some types are more difficult to program than others.
Today, most manufacturers are focusing on features. For example, in the pursuit of the ultimate user-friendly electronic thermostat, Carrier and Bryant have each developed a line of thermostats based on input from consumer focus groups. The resulting products are aesthetically pleasing, have large “positive action” push buttons made from soft rubber, and display useful feedback and system alerts such as a “clean filter” indicator. The units also automatically change over from heating to cooling. In the event of a power outage, they hold their programming up to 72 hours—without backup batteries. These are the types of features to look for if you want a state-of-the-art thermostat that will offer you comfortable, efficient control for years to come.
