Saga of Fantastic Fan Upgrade / Maxxfan Deluxe Installation

Gherzig

A big thank you to @manyman297 for his detailed advice and guidance in replacing the Fantastic Fan with a Maxxfan Deluxe.  His guidance is excellent and gave me the confidence to  rip out a perfectly installed roof fan.  I still did run into some unexpected issues and will share them for those who may follow in the pursuit of the perfect fan.

-Unlike @manyman297. my Fantastic Fan was screwed down into the roof with 18 self tapping  3/4" steel screws.  I discovered this only after attempting to pry off the old fan after removing much of the sealant.  They were not visible as I did not remove the sealant from the top of the flange and they were buried under there.  I had to do some digging to find them all. I do not know if this was due to it being a different model or just a different installation method.  My fan was a model 1450 on a 2021 400BD.
The older 400's had model 1250.  

-My first attempt was to install the Fantastic Fan Upgrade Kit (approx $200 from etrailer). Despite being advertised as compatible with all 14" Fantastic Fans - it is not fully compatible with the model 1450.  Etrailer only agreed to refund my purchase (after installation and removal) when they received a message from Dometic stating that it is not compatible and should not be advertised as such.

-Removing the existing sealant was no easy job and would likely been easier if I had bought a plastic razor as suggested by @manyman297.
I succeeded in removing all the sealant within 1 3/4" of the opening and most of the sealant further out.  As Dicor recommends maintainance by going right over old sealant, I assumed that would not be a problem.  

-Despite being as careful as possible, the scraping and prying did result, to my dismay, in the aluminum sheet roof separating from the layer of insulation below  all around the opening. Before screwing down the new flange, I injected 3M 4000 marine adhesive/sealing under the aluminum so that it would re-adhere.  Hopefully not a problem.

-I did not use the stainless steel sheet metal (not self-tapping) screws that came with the Maxxfan.  I decided to purchase steel self-tapping screws to match those that were in the original Fantastic Fan install.  They had apparently worked well and were designed for the specific nature of the NuCamp roof construction.

-Since I had the tube of 3M 4000 open, I placed a bead of it alongside the butyl tape adjacent to the hole in the roof.  Maxxfan says not to use any polysulfide on their plastic.  I believe 3M 4200 is a polysulfide.  4000 is not.

-I did not worry about applying the butyl tape as one continuous length. I have worked with butyl tape on sailboats and I know from experience that if will meld joints without a problem.  

-It was my first time using Dicor and I used 2 full tubes.  More than needed but I wanted to fully cover the wide area which still had some of the old sealant residue.   

-The Maxxfan is an improvement in a number of ways.  Quieter, moves more air, more energy efficient and probably most important is that you can continue to use it in the rain. 

-The original fan was installed by NuCamp in a quality manner which was designed to be permanent.  Between installing/removing the Fantastic Fan Upgrade and then removing the Fantastic Fan and installing the Maxxfan, I probably have spent the equivalent of 4 days (I know, I work slowly).  Ventilation is an essential item and it boggles my mind as to why NuCamp would install an inferior fan to save $100 in a $40,000+ trailer.  What are seen as little things are often big things.  To me this is an example of being penny wise and dollar foolish.

-Rain is forecast for tomorrow night. Hopefully, no leaks.

manyman297

@Gherzig Glad that tutorial helped you out. It’s my favorite upgrade still. Sorry you had some initial trouble. The model fan they used in my 2021 400 came out super easy. The hard part was dealing with my initial dicor job that started splitting. Luckily removing Dicor on a warm day was fairly easy. 

That fantastic fan is junk. I can’t even sell mine locally. Nobody wants it. The maxx fan is such a huge step up in every way.