Honeywell RedLINK Internet Gateway

“TLDR: get the ecobee Smart Thermostat Essential. Plug in a 24v transformer (see link below) near the thermostat to get the required C wire. The picture of thermostat wiring doesn't offer anything new compared to your original post, there's only one way 2 wire thermostats can be connected. When I asked about seeing wiring it was to see the zoning equipment by the boiler, this will determine how easy it will be to add the Fast-Stat. Your best option is still to get a C wire (again using a plug in transformer or something like the Fast-Stat Common Maker), then use a higher quality smart thermostat like ecobee. The third option is to use a wireless setup (like Honeywell Redlink) to control the zone valves and use the existing wiring for power only. This will be the most expensive and least flexible solution so I do not recommend it. For a transformer it would be something like this: (like [https://www.amazon.com/Transformer-Thermostat-Competible-Versions-Honeywell/dp/B07DJ7RHS5](https://www.amazon.com/Transformer-Thermostat-Competible-Versions-Honeywell/dp/B07DJ7RHS5) or https://www.amazon.com/Transformer-Auto-resetting-Compatible-Doorbell%EF%BC%8CNest-Thermostat/dp/B085WPNC29)”