I built our 3 level home about 4 years ago. It has 3 zone manual dampers (one zone for each level) on an American Standard 2 stage furnace. I have a Honeywell 7 day programmable 5 wire thermostat on the middle level of the house.
The only problem with this setup is in the summer we need to set the thermostat very low to allow the AC to kick on and cool the 3rd floor enough to keep us comfortable (all the bedromms are on the 3rd floor). I have the dampers adjusted to have most of the flow run to the 3rd level during the summer, but at night the middle level cools off faster than the 3rd level so the thermostat doesn't kick on unless I have it set really low.
I have a thermostat wire run from the furnace to the 3rd floor and I was thinking it would be more efficient to install another thermostat on the 3rd floor to solve my summer cooling problem. I probably would only need to use this second thermostat during the summer.
Can I hook this second thermostat up in parallel with the other thermostat at the furnace or will I need some kind of zone controller?
Thank you for the help!!