I recently had my HVAC sub install several Utility Set RTUs to exhaust bathrooms, laundry and ranges in a multi unit building. I didn't question the spec but the owner asked why we did not just do mushroom fans as they look better. My first answer was that the shafts are spaced too tightly to place a mushroom on top of each but he thought we could just duct away from the shaft and up into a mushroom mounted on a frame. The utility sets seem fine to me but I would like to understand the technical reasons behind why one is chosen over the other.

Can the HVAC Community Help me?