I came out to install a bath fan in the master bath. Unfortunately, your ducks for all of these bath fans are 3 inches so I did need to use a reducer, but because of the very short length of the venting, I don’t think this is gonna cause any problems with your efficiency. It does mean the fan is slightly louder, but it is still much quieter than the previous fan. We also discussed adding a new smart switch and outlet in your bathroom closet so that you could plug in a space heater on a dedicated circuit and also have a timer for it and the ability to shut it off when you leave home in case you forget. I’m including a price for that as well. If you end up having those walls tiled before we get to that, please have them cut out a hole to the left of that vent in the tile. The hole needs to be the size of an old work electrical box. Thank you for using TE certified electrical! Veaya