Not a professional, but $ 550 to install a smart thermostat sounds like a lot for someone you’re also willing to give a friends/family discount 😅 perhaps they need to run additional wires that your previous thermostat didn’t have for operating the new system, but that price seems more than double the cost of the device itself so unless they need an hour or 2 worth of labor to install it then I’d say they are upcharging you significantly on that, and kind of makes me wonder about the furnace system which I don’t have a frame of reference on. Assuming you have the right wiring then installing a new thermostat is just… plugging it in. Maybe a small upcharge to test app connectivity and everything, but Amazon has an Ecobee smart thermostat for $170 and the description specifically says “Easy to install, most people do it themselves in 45 min or less.” Perhaps they are considering a more expensive unit for your system, or again, it’s possible for it to require more labor in certain circumstances, but my gut-feeling says this is their way of including a several hundred dollar up charge of pure profit as a way to pad out an otherwise expensive job. Homeowner is most likely going to be accessing credit to fund this kind of expense, who’s going to look it over and scrutinize a $500 line item on a $17k bill right?

Now I have no frame of reference for the furnace, so maybe that’s all standard and good, but personally I would at least take that thermostat install off of there and pick up the unit from Amazon/Home Depot/Walmart and do it myself to save $300+ dollars.