[cstrahan]

I just want a thermostat that gives me the option to specify that I want it to maintain a target temperature, and have it automatically switch between cooling and heating.

The one I have in the apartment I’m renting only gives Cool vs Heat. With Texas being as finicky as it is this time of year, the temperature swings from frigidly cold to swelteringly hot day to day, and with my ADHD and lack of connection to my body, I find myself wondering why I’m feeling run down and mentally foggy, and then I realize it’s because I had to switch to Heat yesterday (because the house dropped down to 60F) and today the apartment is now at 85F, and I’ve been progressively overheating for the past 5 hours or so.

[quickthrowman]

The key to making a functional automatic switch between heating and cooling is an outdoor air temp sensor. You could whip up something with a controller, a few relays, and two temp sensors, one for inside and one for outside.

A thermostat is dead simple, 24VAC and 4 wires: heat, cool, fan, power. You’d need to experiment and figure out where the point will be best to switch from heating to cooling based on the outdoor air temp, the controller would control this.

There might be commercial products available that do this already, but if they don’t have an outdoor air temp sensor, it won’t work.

FWIW I bid and run commercial building automation installations.

[lantry]

nest thermostats (and probably many others) can do this. You set an acceptable temperature range; the heat will activate if it falls below that range, and the cooling will activate if it rises above that range.