I am having a new house built and am putting in a Trane 2 stage forced air furnace and 3 zones controlled with dampers in the ductwork. I inspected the HVAC work yesterday and found that the contractor installed a connecting duct between the supply air and return air plenum. He said this was required to prevent the motor from overheating. The bypass doesn't have a damper and is 8" in diameter. This seems rather big and is it even required??? I feel that on high speed there will be alot of air bypassed that won't make it out to the rest of the home where it's needed. Does anyone know the purpose behind this and can I get rid of it??