A thermostat is a control device that switches the heating system in a house on or off as necessary. It works by sensing air temperature, and switching the heating devices on or off depending on whether or not the ambient temperature is above or below a setpoint.
Thermostats come in many different forms, but most common in modern homes is the programmable thermostat. This type of thermostat adjusts a home's temperature automatically. Programmable thermostats have clocks that can automatically turn the temperature up or down at specified times. These types of thermostats can help save money on energy bills since it turns the temperature down when people are not in the house, or at night when people are sleeping. Natural Resources Canada recommends programming the thermostat for 17°C when people are sleeping or not at home, and 20°C when people are awake and at home.
Although it can be beneficial to turn down the heat in a house a couple of degrees, allowing the temperature to drop too much can affect humidity and air circulation in the house. Particularly, if the temperature in a house drops 4-6 degrees below the average in the winter, a more humid environment is created and can lead to condensation and moisture issues. It can also interrupt proper air circulation as the furnace fans will not be running if the furnace itself doesn't run. Thus it can be beneficial in saving costs to reduce the temperature by 2-3 degrees, but much more than that begins to cause other issues.
Although thermostats perform the same basic function, there are still different types of thermostats. Namely: