I live in Southern AZ in a 2200sqft single floor house. It was built in late 2014 with one unit in the attic and 3 zones in the house each with their own thermostat. The area in one of the zones is rarely used and I'm wondering about what temp that thermostat needs to be set at relative to the other ones. I've been told that all thermostats should be set to within 1 or 2 degrees of each other but if that is the case I can't see the benefit of the 3 zones. I have no experience with HVAC systems and am hoping someone can give me the actual facts on temperature differences among thermostats. Thanks for any info.