I have a fan in one of the bathrooms of a 1930s house and there's a relatively low ceiling. The fan seems to work ok and it's in pretty decent shape(seems to be from 2013), but I think we need a bit more power as we're getting excessive condensation on the ceiling. If my wife and I shower back to back it looks like our ceiling has a leak. I can't seem to find this model (see below pictures) - ideally I'd like to be able to swap out the motor if possible (seems like the path of least resistance). I am decently handy with electrical work (and rapidly gaining more experience in this old house) and can generally figure things out using the good old scientific method. Am I getting in over my head here or is this worth doing myself? Also would that gap cause any problems? Would it help if I use a different paint on the ceiling? I assume it's a standard flat-white ceiling paint, but not sure.
Most consumer-grade fans are not designed for upgrades. My recommendation is to look for a better fan. The 2 key things to look for are:
Airflow - typically measured in CFM - higher is better
Sound - measured in decibels or sone - lower is better
I had a problem in 1 of my bathroom vent fans last year. The duct from the fan to the outlet was run horizontally in the cold attic. After a few years the poured insulated settled where the flex duct was laid. The resulting water that condensed in that trap reduced the exhaust air flow. The settling insulation allowed a trap in the duct to form and the extreme cold in the attic allowed the humid air to condense and fill that trap with water. Check the fan's outlet, "blow open" and the outside vent damper to make sure that both are working properly. Lastly, check the fans's blades to make sure that they are clean and not coated with dust. You can sometimes clean them "in place" with a small screw driver and air compressor if they need cleaned.