by driftwood » Sat Dec 03, 2011 5:24 pm
Not sure type of trailer that a Hunter Fat Shadow is, but below is some advice that another very knowledgable member gave me on installing a roof vent in mine (woody with aluminum roof and only one support.. will be installing a 14 inch Fantastic Fan). I would imagine a lot of this advice would apply to any unit, hope it helps. Will be cutting mine in this winter....and am very nervous about it!
Your opening needs to be 14-1/4" x 14-1/4".
Pictures would help a lot!
Before I continue, what about power?
Assuming you will want to run the fan...you'll need to consider how to get power to the fan.
Probably surface mounted conduit will be the best option.
Wait until you have the fan in your hands though, to know which side or corner it will feed.
It is always best to have the vent opening "between" two roof framing members.
If it is not possible to add another because of sandwich construction, you can do it with one, butted up close, so one side "is" part of the opening.
In either case, you "must" have framing on all 4 sides, as the mounting screws must have something substantial enough to hold onto.
It sounds to me like you have some (sparse) roof framing with a layer of 1/4" ply and aluminum on top of that?
If so, your ceiling is open and it will be very easy to work with.
It should be possible to add another 2x2 rib 14-1/4" over from the existing rib, then add two 14-1/4" pieces between them.
The best way to cut out your opening is to measure 3 times first...
Make a cardboard template 14-1/4" x 14-1/4", use a square to be sure it "is" square.
Since you have an existing framing support, you'll use it as the starting mark.
Determine where you want the vent to start from side to side.
Then place your template against the existing framing.
Tape it in place leaving the corners of the template exposed.
Use a pen or marker to mark all 4 corners, be fairly precise...
Now use a small drill bit, 1/8" or smaller, to drill a hole at each corner of your template, up through the roof paneling and aluminum.
Take your template up to the roof and match the 4 corners to the 4 holes.
If all looks okay (if location is good) then use a marker to mark the square (trace around the template) on the surface of the roof.
Now get some masking/duct/other tape and place it at or near the line, and lay several strips from there outward.
This will protect your roof metal from the jigsaw.
If you cover over part of your lines, just lay the template back down and remark on top of the tape.
It will be wise to apply some tape on the inside, directly on the line of the cuts, to help keep the wood from splintering.
A little is okay as the interior trim ring will cover it, but best to minimize it.
By now, I'm guessing you're happy with the location you chose?
If not, you only have 4 very small holes to patch...
Choose a good metal cutting blade for your jig saw, one designed to cut thin metal. (this blade will also cut the plywood with minimum splintering)
Match the blade width with a drill bit slightly larger.
Use the new drill bit to enlarge the 4 holes in the roof (easy does it, you only need to drill through the metal and paneling, AND NOT DEEP INTO YOUR EXISTING 2X2 FRAMING...)
Once the 4 holes are drilled, use your jig saw to cut out the square.
If you haven't thought of it yet, you'll be much happier if you lay a sheet of plastic, or something inside while drilling and cutting to catch all the debris.
Once cut out, you can frame the opening from the inside.
There is no need, or use for any framing on top of your roof.
Hope this helps, it is much easier and faster to do, than explain...
And his response to a follow up question regarding whether to use a curved garnish or not for the roof:
The location looks okay, but I would suggest considering two things;
First, how much "curve" you have in the roof at that point.
Since the vent, and hole will be in the center, the box framing will straighten out a lot of curve.
If there is too much curve, you may need to move it back a bit, so it is in a flatter part of the roof.
Second, is the box framing, the garnish trim, and the knob/controls will hang down into the space directly above your head...
If you have enough clearance, great.
You have very little roof support.
Adding the framing will provide a stronger roof, a good thing.
As for wiring, you should always fuse everything.
Even if it is only inline fuses, it should be so.
Were it mine, there would be a fuse at the battery, then a fuse before it went into the converter.
If your converter has an output (12 volt) you can connet the fan wire there.
If not, you need to conne t the wire from the battery to a junction box, or fuse panel, then run a wire to the converter, and another to the fan.
