Quote Originally Posted by limahvac View Post
Ive had a similar prob with honeywell 8000 series, second stage with dual fuel ONLY engages when balance point drops below setpoint....no matter how low the house temp gets! Junk! Damn it CARRIER! why did you do away with a good dual fuel stat!
The Vision Pro IAQ would do a much better job with a dual fuel system that has 2 stages of gas heat.

The 8000 series thermostats can't cycle 2nd stage of the furnace, so the furnace has to be set/wired to bring on 2nd stage based on time, or based on outdoor temperature with a outdoor thermostat.

The Vision Pro IAQ thermostat will cycle both stages to maintain the set point when using the furnace.