You can also snap a picture of your thermostat wiring and email it to Ecobee so they can verify you’re compatibility. I’d snap the picture, explain your setup, and email it to them on the website, they’ll get back to you pretty quickly.

If you currently have two thermostats, one up and one down, you’ll likely need the same with a smart thermostat. If you only have one right now then sensors should do the trick going forward.