By maintaining the highest or lowest required temperatures for four or five hours a day instead of 24 hours, a programmable thermostat can pay for itself in energy saved within four years. Programmable Thermostats Programmable thermostats have features with which you may be unfamiliar. The newest generation of residential thermostat technologies is based on microprocessors and thermistor sensors. They store six or more temperature settings a day. They adjust heating or air conditioning turn-on times as the outside temperature changes.
Most programmable thermostats have liquid crystal temperature displays.
Some have back-up battery packs that eliminate the need to reprogram the time or clock in case of a power failure. Understanding your air duct system can improve the heating and cooling in your home.