[mmglr]

My house has a Carrier Infinity system where the compressor and air handler is fully variable. It can retrieve weather data over the net and adjust heating/cooling. The compressor and air handler are "connected" which is HVAC lingo for a proprietary protocol. The brains are in a $700 thermostat with a buggy touch screen that has the resolution of a lite-brite and it cannot work with virtual assistants.

One benefit I did see in the manual, is that if the air handler was gas combined with a heat pump you can enter the price of electricity and the price of gas and it can compute which heating method is best: gas/heat pump/resistive (usually when heat pump cannot provide requested temperature). But I don't have gas.

ROMs are available for these systems distributed as hex files on Carriers website. So its been on my todo list to reverse engineer the software.

Someone with time combined with a Raspberry Pi + Raspberry Pi Display (around $80 USD) could build a much better thermostat than what Carrier has done.