Join Date: Jul 2018
Location: West Palm Beach
Mentioned: 1 Post(s)
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I've done 2 fan installs using Hein's adapters.
On the first, I used window weld as he recommended. It's nasty stuff. In order to get a great 'bond', it needs the activator that's used when they do a window install using that stuff.
On the second fan, I used 3M 4200 fast cure marine adhesive. 5200 is great to use also, but is a more permanent adhesive. Both are urethane based adhesives as is the window weld from NAPA. The cost is about the same.
Make sure you get the "fast cure" 3M adhesive if you use it, not the regular cure which will take a week to harden. The 4200 or 5200 fast cure will be firm in an hour, and solid as a rock the next day. It's messy stuff no matter which one you use.
I also added supports from the rear cross rib, to the next one forward. You'll see the sheet metal is extremely thin and flimsy and really doesn't offer much support. I'm glad I did. Like the other poster said above, you'll need material on the inside of the roof that will allow you to attach the plastic trim piece once the fan is installed. The last thing you'll want is a flimsy foundation that will move, warble, or vibrate when going down the road. Do it right the first time.
I glued the fan adapter from Hein first, and let it cure overnight. It was solid the next day. MAKE SURE you scuff the paint with scotch brite, or 220 sand paper before gluing the adapter to the roof top. After that, put your upper fan flange in place, mark the holes, remove the fan flange, drill them (right through the adapter and metal roof)
Then, apply the butyl tape over the topside of the adapter. Place the upper fan flange back on top and fasten it securely with sheet metal screws. FYI the butyl tape will ooze ouf on the sides and also sag on the inside, especially when the sun heats things up.You don't have to use silicon caulk with the screws, but it can't hurt either. You don't need any leaks.
After it's all secured, I also applied GE Silicon II to the whole top side of the upper flange as well as the outside of the adapter where it meets the rooftop.
Overkill... yeah. Who cares? I don't want any leaks...