Now that I can use my Amazon Alexa’s to send MQTT packets, I wanted to be able to switch between Heat and Cool on my HVAC systems without having to run around the house to all the thermostats to make the change. After hunting around on the Internet for a while, I did manage to find some Node.JS code that could read the current temperatures, settings, and whatnot, and also be able to set both the mode (IE> Heat/Cool/Off) as well as the activation temperatures for each mode.
I took that code and added the ability to report out every few minutes what the current temperature readings were via MQTT, as well as accept two MQTT packets to turn on Heat or turn on Cool. The results are out on my Github Repositories. The code can set my Honeywell Total Comfort RTH6500’s to Heat or Cool or Off. It also supports an ‘Auto’ mode, but my RTH6500’s don’t have that option….as far as I know.