We love sleeping with the rear windows open on our Phoenix 2552 using the factory installed fantastic fan just above the beds. But we find it a little noisy and wish it had slower speeds. To solve this I installed a Maxxfan Deluxe in the front ceiling vent.
I was not sure how I would tap into the 12v wiring to power the fan but actually was quite easy. After the removing the old vent I could pull down the roof paneling and fish a wire up the 12v light just in front of the fan and just tied into the wire nuts of the overhead light.
Installation took about 2 hours, we are really pleased with this new installation and love all the features such as remote control, 10 speeds (In the lower speeds it is almost silent). Reverse cycle meaning you and actually reverse the fan and pull air into the coach. Which we then push out with our rear Fantastic fan when it is really hot. Now we can find the perfect speed to keep air moving at night with no noise in the bed area even with the fan at higher speeds.
One other little bonus is this fan has a thermostat that will turn on the fan at 78 degrees with a little green LED light that makes a great night light up front.
Although a little pricey we are really happy about this upgrade.
http://www.campingworld.com/shopping/item/maxxfan-deluxe-remote-control-rv-ventilator-system-white-lid/48933