Where I’m at, the temps flip-flop day to day, even hour to hour. In the morning it’s 35° outside, and by evening it’s 79°. I gave up keeping up with the temps and shut my unit off for the time being.
My question is why can’t HVAC units be programmed to say that if the outside temp reaches n° and the inside temp reaches m° cold, turn on the heat; conversely, if the outside temp rises to n° and the inside temp reaches m°, then turn on the AC?
My thermostat already knows the outside and inside temp, but I still have to manually switch it back and forth. I want a system that I can just set it and forget it all year round.
That absolutely 100% exists. In commercial buildings, this is the standard. Nobody has to go to the BMS (Building Management System) and tell it to switch to cooling or heating. It’s all automatic. Even higher end residential thermostats do it. A couple of years ago I had my gas furnace replaced with a heat pump/electric heat system and it automatically switches between heat and cool as I’ve programmed it.
Hell, you can get systems that are sophisticated enough that every individual room in your house has an independent thermostat that automatically maintains a different temperature in each room. Of course, that’ll require a separate VAV for each room, which isn’t common in residential buildings.
The primary reason you don’t see “smarter” systems in homes more often is because they’re more expensive. Most people leave the fan on their HVAC system on auto and just switch between hot and cold manually as needed. And for most people, that’s only a few times per year. Most people switch it to cool sometime in the Spring, then leave it there until the Fall when they switch back to heat.
A more complicated system is just paying more money for something you don’t really need.
Depends on how shitty your contractors are and how cheap your construction team is ☹️