What is multistage heating and cooling and how do I tell if I have it?

Part of figuring out if your system is compatible with a smart thermostat is determining if your 24v HVAC system is single stage or multistage. (Wait a minute, how do I tell if I have a 24v HVAC system in the first place?) Single stage systems are best described as “on-off“. They’re either blowing hot […]