Since the headliner was down for the insulation, we tackled the ceiling fan install next. We chose the Ventline VP-543 12V Smoke Van Roof Air Vent because I liked the idea of having a round fan for aerodynamics, instead of a flat edge. It also fit quite nicely between the roof braces in the rear of our Chevrolet Astro. The Fantastic fan is also nice, but I think it's overkill for the size of the Astro.
The idea of cutting a big hole in the roof was a little daunting, the easiest way to do it I found, was to stop over-thinking and just get stuck in.
So how did we do it?
The unit has 2 parts, the top piece consisting of the motor that goes down into the van, and an interior trim piece that attaches from the bottom. I made a pattern from cardboard by pulling the 2 pieces apart and tracing around the outside edge of the tube that slips into the future hole. I made sure to cut the cardboard circle on the inside of my line which will be the right size that I need to cut my roof hole. Sure, I could have just cut a 6.25 inch hole, but what if the instructions were wrong?
Inside the van, I centered the cardboard cutout on the flat area of the ceiling in the rear of the van. I did this from inside the van so that I could be sure I wouldn't damage a roof support or something else important. I then drilled a hole up through the roof in the centre of the cardboard pattern. Next, I climbed onto the roof of the van and centered the cardboard cutout on the hole. I traced the circular pattern using a marker. Afterwards, I covered the surrounding area with masking tape to protect the area that the jigsaw might rub. I started by drilling a pilot hole at the edge of the circle I had traced with a marker, then fired up the jigsaw, took a deep breath and started cutting a big hole in my roof.
After a test fit, it was still a little tight so I used a metal file to smooth out the rim and enlarge the hole. It turns out it needed a bit more so I took a couple of really narrow passes with the jigsaw just shaving the edge. This put the hole into contact with a support bar for the roof, not a major inconvenience as it was just a small slither at the perimeter.
The hole and the fan finally matched up; I inserted the fan and marked the screw holes to make pilot holes. Fan back out, I drilled tiny pilot holes that the screws will go into to hold the fan down. I utilized a couple of products to ensure the fan would be water tight: firstly I put down a layer of vent putty tape, then put down a layer of rubber roof lap sealant. I let the sealant dry just a little, then inserted the fan down the hole, gave it a firm push down and hoped the holes were aligned with my pre-drilled holes. A little bit of adjusting and they were aligned so I ran all the screws in. Not tight at first. I got them all in, then going clockwise, made each screw a little tighter and moved to the next. It took a couple of laps for them all to be snug. I didn't want to over tighten and pull the screw through the roof so I was quite gentle. I'm not sure if there's anything to this, but it made sense in my head and no leaks yet (we live in Oregon now).
On to the outside: If I was a smart man, I would have installed the rear headliner while I had a hole in the roof and marked the top side of the headliner through the roof. That way I would have just cut the marked hole and re-installed the headliner. Instead I had to guestimate where the hole was and do lots of trimming with the jigsaw. I don't have an auxillary battery yet, but I did wire it up and ran wire to where my fuse box will be in the future. It all worked out in the end, headliner back up, trim ring fitted, no screws were needed on the trim as it's a tight fit.
(Fast forward a few months and I've just completed the wiring to the fuse box and I'm happy to say it works as it should.)
Tools and Supplies used:-
Battery power screwdriver
Rounded metal file
Pencil and cardboard for template
Ventline VP-543 12V Smoke Van Roof Air Vent
Vent installation kit
Rubber roof lap sealant