We elected to set up three zones: first floor, second floor, and basement. However, some rooms on the first floor will be part of the second floor zone. That will make the heating loads of the zones closer to equal. The office will tend to get solar heat gain from the window at the same times that the master bedroom on the second floor does, so it makes sense to have them in the same zone even though they are on different floors.
|The duct system begins and ends at the furnace. A MERV 13 filter is between the return duct on the right and the furnace.|
|Zone dampers are installed in each supply duct where it connects to the furnace plenum. There are four zone dampers, but two of them will be wired to open and close at the same time such that there are only three zones.|
|This shows a return duct and a supply duct routed through an interior wall on the first floor to the master bathroom on the second floor. Most of the return ducts are created by closing off a stud bay. Some articles advise against this practice, but the reasons seem most applicable to ducts located outside of conditioned space. Return ducts formed this way must be on interior walls. The supply ducts use oval metal duct within a stud bay. It is better to route supply ducts through interior walls, but we were forced to use exterior walls in some locations. Fortunately, even in those locations, the ducts are still inside of the rigid foam insulation.|
|The kitchen, at least, was straight forward. The supply duct will be under the sink in the island.|