In modern day homes nowadays, the most common central heating and cooling systems can be 24V, oil, gas, heat bump or electric. However heat pump systems are more efficient than other heating ones as they allow you to choose how much auxiliary heat to use. It’s said that a smart thermostat can be compatible with many types of HVAC system, but you don’t set up a thermostat and realize it doesn’t work, simply because that thermostat doesn’t not support your heating and cooling system. Remember, compatible or not, this thing needs to be confirmed 100%!