Years ago almost every home had a round or rectangular thermostat that had a small vial filled with mercury, which was actually the contact point for the 24 volt circuit. The only thing these thermostats were designed to do was to turn the equipment on or off.

Programmable Thermostat

Approximately 40 years ago Honeywell began mass production of the mechanical programmable thermostat. They worked on the same principle as most landscape irrigating systems. With the rapid change in technology, almost everything today is digital. Some of the most popular thermostats today are:

Digital Nonprogrammable – This is a digital readout thermostat that you set and leave. The temperature stays consistent unless you change it.
Digital Programmable – Much more popular because you can have two setback positions in a 24 hour period. Usually nighttime and daytime.
Wi-Fi Thermostat – These allow you to check and adjust your home comfort level from anywhere in the world via the Internet.
Communicating Thermostat – These take the Wi-Fi to the next level by adjusting the comfort level based on need via the modulating furnaces and inverter compressors. Many of these thermostats can also be tied into a home automation system like lighting, burglar alarm, video camera, etc.