Programmable thermostats save energy, save you money and maximize comfort based on your unique schedule! They typically have four setpoints, allowing you to set different temperatures for the morning, daytime, evening and over night. Most programmable thermostats can operate in a non-programmable mode if you choose not to set a program. A non-programmable thermostat's settings must be manually changed for temperature and on/off functionality.

Application Type

Thermostats vary by the different types of heating and/or cooling units they control.

  • Heat Only - works only with a single heating source.

  • Cool Only - works only with a single cooling source.

  • Single Stage Heat/Cool - controls one heating source and one cooling source.

  • Multi-Stage Heat/Cool - controls multiple heating and cooling sources.

  • Electric Heat/Line Voltage - controls electric baseboard and electric heaters.

  • Heat Pump - used in heat pump applications, such as air source heat pumps and ground so.urce heat pumps.

  • Fan Coil - work with fan coil units, such as unit ventilators.

  • Millivolt - used to regulate systems that utilize a pilot light rather than an electrical circuit, such as a gas-fired water heater.


This refers to the number of heating or cooling sources that may be controlled by a single thermostat. For example, if a system contains baseboard heat, a hot air system and air conditioning, then there are two heating stages and one cooling stage. In this example, a 2 heat/1 cool thermostat should be installed. Note: If you have auxiliary heat (backup heat, such as a fan coil or baseboard), that counts as a second heating source. The number of stages may be written in several different ways. The most common are 2H/1C or 2 Heat/2 Cool; both mean that there are two heat sources and one cool source. The number of stages can vary from single heat or single cool up to 4 Heat/3 Cool on a single thermostat.

User Interface

Thermostats are operated using a digital touchscreen, buttons with a digital screen, or simple mechanical dial.


Thermostats run on either line voltage or low  voltage. The easiest way to tell if you need a line or low voltage thermostat is to look at the wire. If it's a very thin wire (like a doorbell or speaker wire), you'll need a low voltage thermostat. If it's a heavy wire, you'll need a line voltage thermostat.

Changeover Type

Thermostats either have automatic changeover or manual changeover. Thermostats with auto changeover switch from heat to cool automatically depending on the indoor temperature, while thermostats with manual changeover will remain on either heat or cool until you change it.