Thermostat Controls

The primary objective of either space heating or air conditioning is to maintain a temperature difference between indoors and outdoors. The greater the difference in temperature, the greater the energy use and expense. While we obviously have little control over the outdoor temperature, we can affect the temperature difference by adjusting the indoor thermostat. Lowering the thermostat setting a few degrees in winter reduces the indoor/outdoor temperature difference, saving energy on space heating. Each degree of setback can save from one to three percent. Similarly, raising the thermostat setting in summer can reduce air conditioning expenses by three to five percent for each degree.

Programmable Thermostats

Programmable thermostats allow you to specify different temperature settings at different times of day and for different days of the week. You can set the temperature back while sleeping or at work, and program the thermostat to return to the normal setting prior to waking up or arriving home. This helps you save energy on heating and air conditioning without waking up to a cold house in winter or arriving home to an overheated house in the summer.

There are a wide variety of programmable thermostats available, ranging from simple ones that allow for one or two setbacks a day to very sophisticated ones that allow different programs for every day of the week. In most cases, the best option is the simplest one that meets your needs (otherwise you can end up bypassing the programmable features and simply controlling it manually). Consider your schedule and determine the number of setbacks and different settings you'll actually use, and select a thermostat with those capabilities.

If you have a heat pump, check the manufacturer's literature and specifications before purchasing a new thermostat. Most heat pump manufacturers offer programmable thermostats designed for their systems. A mismatched or improperly used thermostat can actually increase the operating cost of a heat pump by increasing the use of the more expensive back-up heating elements. Manual setbacks are not recommended with heat pumps - when you set the temperature back to the normal setting you may be relying on the back-up heating elements, causing overall costs to increase.

Thermostat Maintenance

You should periodically check your thermostat for accuracy, as they can sometimes "drift" over time. Place a cooking thermometer on top of the thermostat and leave it there for ten minutes or so. Then check to see if the temperature shown on the thermostat agrees with the thermometer. If there is more than a one or two degree difference, the thermostat may need to be recalibrated or possibly replaced. It's a good idea to have your heating and air conditioning contractor check the thermostat as part of your annual maintenance.

Recommended Settings

Recommended thermostat settings are 70 degrees or lower in winter and 78 degrees or higher in summer. These settings should result in a comfortable indoor temperature. You should also turn the thermostat down ten degrees or so (in winter) or up about five degrees (in summer) when leaving the home for several hours or more. A programmable thermostat can make these adjustments automatically and will never forget. Setting your thermostat back in winter and up in summer when sleeping or away from home can save you as much as ten percent on your annual space heating and air conditioning expenses.

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