Another common example of a feedback loop is a thermostat and home heating (or cooling) system. If the temperature in the home is lower than the set point of the thermostat, the thermostat sends the appropriate information to the heater, switching it on. The thermostat constantly reads the air temperature, and when the home has reached the set point, shuts the heater down. When a home grows too warm, the thermostat will interact with the cooling system in a similar manner to lower the temperature back to its set point.

Theoretically, the temperature inside the home should not change, as long as the thermostat set point remains unchanged. However, the home temperature naturally varies around the set point due to lag time and ability of the system. Both positive and negative feedbacks work to alter the inputs of the system; the cooling works to lower the input temperature, and the heating works to raise the input temperature. Later, you will learn how carbon dioxide acts as earth's thermostat.