My wife and I recently purchased a foreclosed home as a starter home for our daughter. Its a small ranch home built on a slab with supply ducts in floor and a central return in hallway where filter is located. The home is only about 1200sq. ft. We have been gutting the home and we had our heating and air contractor add central air to the existing downflow furnace that is only a couple years old. When the township inspector came in to look at our electrical he looked at the furnace and told us that the return air would have to be changed. It has a cover or sheet of metal over the top of the return air opening and from that cover or cap there is a 14" round takeoff that goes about 7 feet over through the ceiling to the return air filter access. The inspector says that the top of the furnace or the return side cannot have a cover like that right on top of the furnace with the round takeoff but rather has to have a plenum that is the size of the factory furnace opening on the furnace and the takeoff off of that. Our contractor says that the blower speed is on a low setting and that the furnace temperature rise is within factory specifications and that the current setup is acceptable, so who is right? The contractor says that the inspector is a new inspector and trying to nitpick and not know exactly what he is talking about. All that I can find in the furnace installation manual on the return air opening on the furnace (Goodman 80% downflow) is that it says reducing return air opening size will reduce airflow. It does not say that it cannot be done. I do not want to argue with the inspector but I also want to know if this plenum really needs to be added. What difference would it make if there is a plenum and you still have the same size takeoff coming off of the plenum? And is the furnace temperature rise the correct way to know if the current return air is acceptable for the furnace?