Airflow is balanced throughout house. I suspect the nest thermostats are behaving weirdly or doing some efficiency thing One supply duct has a return vent and a return duct has a supply vent. They are not the same size Installed IAQ200 and sealed a duct in a couple places to prevent air leakage and biological growth forming from previous water issues Quoted two methods to handle the humidity of the newly spray foamed attic as the systems are already sweating and dripping water in the attic Homeowner will get back to us with his decision