We had the two 4" vents installed in the hatches at the galley and the head. The galley vent is an intake vent, while the vent located in the head is exhaust. Each of the 4" vents moves 1000 cubic feet of air per hour, which should be more than sufficient in keeping the air moving on our Gemini 3200. When we reviewed the installation of the vents, we noticed that the vent in the head was not working. After a little trouble-shooting, it was determined that the battery that came with the unit was bad. A replace battery is now on our "Need To Purchase" list.
The 3" vent was installed as an exhaust vent for our Nature's Head Composting Toilet, where the old pump out fitting was located (This is the 6th of 7 steps).
**SAILRITE COUPON** I received an email this weekend from Sailrite with there latest deal. "Purchase an Ultrafeed Sewing Machine (#102500, 102600, 102700, 102800) from Sailrite between 5/28/2010 and 6/7/2010 and receive a free $100 Sailrite gift certificate for use on future orders."