When we got our RV we turned on the bathroom vent fan and were assulted by a loud roar like a helicopter taking off. It cerainly was not a queit RV vent fan. Then we did some cooking and turned on the vent fan above the stove and MORE OF THE SAME racket. I wonder why they put these cheap noisy fans in the living space of an expensive home.
I found two round 12 volt fans used for circulating air in electronic equiptment. These fans are ball bearing mounted and very quiet. It was easy to remove the shroud on the inside of the bathroom vent. It was held in place by four screws.
I disconnected the house battery so there was NO ELECTRICITY at the fan wiring or switch.
Next I took out the old fan and installed the new QUIET fan in it's place. I had to adapt the new fan slightly by drilling a couple extra holes in the already existing brackets. You might have to make a couple brackets depending on the fan you get. I wired the fan it to the old switch and was ready to test it. An easy job. The fan worked perfect and best of all was super quiet.
When I reinstalled the shroud with the screen, I was lucky and the fan didn't touch anywhere. Others have had the fan rub on the screen. You can easily put in two or four spacers to keep the fan away from the screen.
The only problem I had was after I had it all together, my crank handle to open the vent cover wouldn't fit. The new fan was thicker and pushed the screen down to the point that the crank shaft was too short. I went to my local RV supply store and bought a long shank crank and was back in business. It worked just like the old one.
My fan is made by Comair Rotron and is model PQ12C4 in their PATRIOT line. After some research I found that my new fan did not move quite as much air as the old noisy fan, however, it was only slightly less and it still moves plenty of air out of the bathroom. My fan 6 3/4 inches across. It draws 1.8 amps of current at 12 volts DC. If the fan you look at draws much less current than this, it is probably too small.
I found my fans on Ebay. You can do a search on Ebay for "12 volt fans". They come and go so check back as needed.
One caution when buying your fan. Check the model and look up the company on the internet. Be sure your fan isn't one of the small 3 or 4 inch fans that don't move much air. My fan moves 205 CFM (cubic feet per minute) of air. Most of the little 4 inch fans only move about 70 to 100 CFM. That is not really enough for an efficient fan.
I am very pleased with both of my replacement fans. My wife would not use the kitchen fan because it was so noisy. Now it's a pleasure to exhaust cooking odors using a quiet fan.
This is a do it yourself project where you find your own fan, research its capacity and do the installation by rigging brackets and adapters yourself. If you are more interested in a ready to install fan, check out the Turbo/Maxx or Fan-Tastic Fans