ROOF VENT INSTALL
The roof fan selected was the Maxxair Model 6200K manufactured by Airxcel Inc. The fan has the smoke colored lid. This fan does not have a remote. I would loose or drop the remote. Fan location makes it easily accessable from the aisle or the bed. The Maxxair has four features that are better than the Fantastic brand fan. The lid is designed so fan can be open in the rain, the fan does not require a rain sensor, the fan has two support arms instead of one and lid can be open when driving. The ability to be open in the rain is important. The fan lid either has to be fully closed or fully open when driving. If partially open the lid lifting gearbox will fail.
The fan has 10 speeds and can control the speeds with a thermostat that changes speed with a change in temperature. The fan is reversible so can exhaust or intake air. In my application it is always used to exhaust. The fan amperage changes for different speeds: Speed # 1 = 0.2, Speed # 2 = 0.3, Speed # 3 = 0.4, Speed # 4 = 0.6, Speed # 5 = 0.9, Speed # 6 = 1.2, Speed # 7 = 1.6, Speed # 8 = 2.0, Speed # 9 = 2.6 and Speed # 10 = 3.7. I seldom power the fan. With the floor hole I get a natural draft from the floor hole and out the open roof vent. That is normally enough air flow to keep the van interior close to the outside ambient temperature.
The fan is located between two van ribs about 21" forward of the Transit rear door frame. There were multiple reasons to select that location. Wanted fan over bed platform, it is close to the 4" square hole in the van floor, the 300 watt solar panel forces that location and the Transit has 14" between the two roof rib flanges at that location.
Ford did not make it easy to install a fan. The 14" square hole is easy. The problem is the Maxxair flange holes are located over the Transit roof rib flange on the front and back and the side holes are located over the lower roof corrugations on the sides. Had to have spacers on all four sides under the roof and on two sides on top of the roof.
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1. Make a 14" square 1/4" plywood pattern with four 9/32" holes in the corners. They are located 7/16" from the edge of the plywood. One 9/32" hole in the center.
2. Hold the pattern against the roof with a stick to center the pattern. Drill the center hole and bolt the pattern to the roof. Align the pattern.
3. Drill the four corner 9/32" holes in van roof. These holes are the location for the electrictian's 1/2" NPT knockout punch that will be used. The punch is 7/8" diameter. Enlarge the four holes to 3/8" for the punch thread. Punch the four holes. Mark straight lines tangent to the holes.
4. Hang a drop cloth under roof to catch the cuttings from the jig saw.
5. Put painter tape on outside of cut line so jig saw plate does not scratch the paint outside the 14" hole. Tape cardboard or newspapers around opening outside of painters tape on roof top to keep any saw cuttings from getting on the roof paint.
6. Using jig saw cut out the 14" square opening. After a each cut is made use duct tape to hold the cut part to the roof. Do that in 3 places so 14" square part does not drop. Do not stand on the van roof. It will dent. With my fan location I could reach the hole cut from the back of the van. Made a platform bolted to my pickup bed for access.
7. Debur opening and paint raw edge.
8. I did not want to use sheet metal screws to attach fan housing to the roof. Bought sixteen 10-24 x 2 1/2" stainless machine screws. Made a 3/4" thick plywood picture frame to place under roof. Frame inside dimension is 14" and outside dimension is 16 1/2". It fits between the two van ribs. The van ribs have a raised bump on the flanges and a deeper flange at the corners to go around the roof corrugations. Glued pieces of wood 1/4" thick x 1 1/4" x 13" to the picture frame parallel to the roof ribs. The sides of the picture frame perpendicular to the roof ribs are located below roof corrugations. Glued a 7/16" thick x 1 1/4" x 13" pieces of wood to the sides of the picture frame. If I was going to do it again, I would use a 1/2" thick picture frame and 10-24 x 2" stainless machine screws.
9. Put three 13/64" holes in the sides of the frame so it could be bolted to the roof. Used the Maxxair plastic roof flange to locate the three holes. Two on one side and one on the other.
10. Clamped picture frame under the roof and drilled three 13/64" holes through the roof from below using the three holes in the picture frame as a guide. Bolted the Maxxair plastic roof flange and the picture frame in place.
11. From above using the Maxxair plastic roof flange holes as a guide drilled the other 13 holes through the roof and the picture frame.
12. Removed the parts and painted the picture frame and the holes in the roof.
13. Made four 1/8" x 1" aluminum strips to distribute the screw head load. Had been told that the plastic roof flange will eventually crack at the bolt holes. Strips should eliminate the cracking.
14. Made two 3/32" x 7/8" x 16 1/2" Trex plastic wood strips to put in the roof corrugations to get a flat surface for the Maxxair flange. Drilled the Trex for the flange holes and radiused the corners to match the flange.
15. Put vent putty strips around the opening on top. Two thicknesses on the sides. One under the 3/32" spacer and one on top. Used an awl to punch bolt holes in the putty.
16. Bolted plastic roof flange down to roof. The aluminum flats were installed on the top of the Maxxair flange and fender washers and elastic stop nuts were used under the picture frame.
17. Used a putty knife to remove the excess putty.
18. Used Dicor self leveling lap sealant # 501LSW around the flange and covered the machine screw heads and around the aluminum strips.
19. Installed fan.
20. Later added four wood block spacers to the picture frame to provide for garnish ring retaining screws.
21. Wired with 16 ga. cord from the DC distribution with a 5 amp fuse.
Unfortunately I dented the van sheet metal above the rear doors by leaning on it. Should have put a cloth down and put a piece of plywood on the cloth to distribute the load. Did not expect it to be that weak. I certainly would never walk on the roof.
The issue that might be a problem for someone is the finished install has the 10-24 screw thread ends 1/8" to 3/8" below the roof rib. A ceiling panel bolted directly to the rib would hit the screw ends. In my case I have a flat ceiling that is spaced down 1 1/4" from the roof rib at the center of van so screw ends were not a problem. A 1/2" thick picture frame instead of 3/4" would solve that problem. 2" long 10-24 screws could be used with the 1/2" thick picture frame.