The gas heater thermostat is the point of contact between the furnace and the homeowner. With the thermostat, the user controls the actions of the furnace from a distance. When choosing a gas heater thermostat, consider a programmable thermostat for energy efficiency and superior control. Avoid older thermostats with mercury. If the thermostat will be in a visible place in the home, select an attractive model with an easily controlled interface.
There are three basic types of gas heater thermostats: mechanical, electronic and programmable. The mechanical gas heater thermostat is the simplest in design and operation. Homeowners turn the dial or small lever to the right or to the left to control the furnace output and accompanying room temperature. Older mechanical thermostats contained mercury, which should be avoided due to the toxic properties of the metal. Newer, safer thermostats contain a coiled metal strip that contracts or expands with the surrounding room temperature.
Electronic, or digital, thermostats feature a digital display showing current room temperature and desired temperature settings. These types of thermostats differ little from the basic mechanical thermostats, but offer more detailed temperature information. The digital thermostat needs electricity to operate. Some require batteries and others connect to the home's electrical system, so take this into consideration when selecting this type of thermostat. The main advantage to the digital thermostat is the liquid crystal display (LCD) screen, but this type of thermostat is not programmable.
Programmable thermostats are recommended by utility companies and gas heater installers as the most efficient and energy-conscious choice among thermostats. These units feature larger LCD touch screens or buttons that allow you to pre-set multiple options for the furnace. You can set the thermostat to automatically warm the house 30 minutes before arriving home from work or to shut down to a cooler temperature while the family sleeps, and you can adjust these settings according to specific days. Some of the more expensive models display the weather, indoor and outdoor temperatures, and more. As with the digital thermostat, the programmable thermostat requires an energy source via battery or electrical system to power the unit.
Finally, consider the ease of installation and appearance of the gas heater thermostat. Many newer thermostats can be installed using the existing 24-volt furnace wires, but an older millivolt wiring system will need replacing. If you are purchasing a fancy new programmable thermostat but do not want to open the wall to run wiring, consider the battery-operated unit. Most thermostats are manufactured in white plastic, and cheaper models yellow with age. If the thermostat will be in a visible area, such as a formal dining room or living room, consider a more attractive-colored thermostat and avoid installing a gas heater thermostat in direct sunlight.