Our house has no returns on the 2nd floor. Needless to say the air does not move well and upstairs is 5-7 degrees warmer in this heat. We don't have a good way to run returns to the basement from the 2nd floor. Our technician suggests that he zone the system. The thought is that when the 2nd floor is on but the first is off the pressure will cause the 2nd floor air to travel down the stairs and this draw the hot air downstairs.
Seems reasonable but odd. Thoughts ?