Hello koohram,
Thanks for considering upgrading your thermostat to a Nest Thermostat model. However, the compatibility of Nest Thermostats can vary based on your HVAC system and the wiring configuration.
The Honeywell T6575B thermostat you mentioned has nine wires, and Nest thermostats typically work with systems that have a common wire (C-wire). It's essential to check if your current setup includes a C-wire, as some Nest models may require it for proper functioning.
To determine compatibility, can you share with us a photo of your thermostat's wiring setup? Also, the make and model of your HVAC system and what type it is.
I'll look forward to your response.
Best regards,
Mark
