Controls & Thermostats

Thermostats regulate the operation of central heating and cooling systems, as well as many space heaters. By setting the thermostat to the desired temperature, the heating or cooling system will operate until the desired “set-point” is met and then generally turns the system off. If the building temperature drifts below (in winter) or above (in summer) the set-point, then the thermostat turns the system back on. Other heating devices use controls, such as knobs for on/off or high/medium/low. Their settings are not typically tied to specific temperatures.

You may be able to save money on your heating and cooling bills by simply resetting your thermostat when you are asleep or away from your home or office. Although thermostats can be adjusted manually, programmable thermostats may be able to help you avoid discomfort by returning temperatures to normal before you wake or return to your home or office. With three different types of thermostats, you can identify the type that may work best for you, your daily routine, and your heating system:

  1. A manual thermostat requires you to adjust the heating and cooling levels manually
  2. A programmable thermostat allows you to set the hours, days and times during when your heating system will turn on/off or raise/lower the temperature
  3. A "smart" thermostat will study occupant behavior in your building, estimate the temperature you prefer when you are at home or in the office, and allow you to set the heating and cooling remotely via a smart phone

The location of your thermostat can affect its performance and efficiency. To operate properly, a thermostat typically must be on an interior wall away from direct sunlight, drafts, doorways, skylights, and windows. It should also typically be located where natural room air currents (rising warm air, sinking cool air) occur. Furniture will block natural air movement, so you may not want to place furniture in front of or below your thermostat. You may also want to make sure your thermostat is conveniently located for programming.

A common misconception is that a heating system works harder to warm the space back to a comfortable temperature after the thermostat has been turned down, resulting in little or no savings. In fact, the lower the interior temperature, the slower it may lose energy to the surrounding environment. The longer your building remains at the lower temperature, the more energy you may save. Turning your thermostat way up when you come into a cold room will not necessarily warm it faster than turning it to your desired temperature. Something to consider is that setting back the temperature means that other locations in the building may also get colder. You may want to protect your piping from freezing in the appropriate ways.

Some Benefits

  • Programmable and "smart" thermostats may make it easy to lower or raise the temperature to save energy when no one is occupying a room or building
  • Using thermostats that control different zones, or areas, in your building allows you to heat or cool the space you are in to a more comfortable temperature than unused rooms

Some Considerations

  • Some "smart" thermostats require power to the thermostat, which may necessitate the installation of an additional power supply. This may increase your electric bill and require an electrician to install.
  • Programmable thermostats offer a variety of features and complexitysome people may prefer to adjust their existing/conventional thermostats manually. Other limitations of programmable thermostats may include:
    • When a heat pump is being used during the winter, lowering its thermostat setting can cause the unit to operate inefficiently and may cancel out savings achieved by lowering the temperature setting. Additionally, heat pumps may take a long time to recover after reducing the thermostat setting, which may cause comfort issues.  The conventional wisdom for heat pumps is typically "set it and forget it."
    • With steam heating and radiant floor heating systems, having a programmable thermostat raise the temperature 15 minutes before you wake up in the winter will not usually result in the warmth you are expecting, as it typically takes a longer time for the system to heat up overall
    • With radiant systems, the total energy saved may not be significant enough to warrant using a set-back

Some Next Steps

Changing thermostats can be an easy way to save fuel and increase comfort.  It’s worth doing a little research into the wide range of prices and features offered before deciding which one you want to buy. Energy.gov has a page dedicated to using thermostats.

Learn More

Visit the pages below to learn more about Heating & Cooling:

Central Heating

Space Heating

Cooling

Heat Pumps

Solar

Controls & Thermostats

Department of Public Service
June E. Tierney, Commissioner
112 State Street
Montpelier, VT  05620-2601

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