Silicone / No Silicone for Fantastic fan

[polarlyse]

I just today ordered 2 fantastic fans from Vintage Trailer. I went yesterday to Fastenall and found a TremPro product, no silicone, to seal the fan. Today while speaking with the people from VT he insisted that you need to use the recommended procedures and recommended sealant. The one they use is a silicone type. He said that only a silicone sealant will adhere to the plastic housing and if you don't other sealers will crack and allow water in.

Many of you in Airstream Land have installed the fantastic fans. What sealant have you all been using ?????? He also said that if you follow the directions from Fantastic you will be using very little sealant to do the job.

Thanks all,

[whitelight]

I looked at the FAQ pictures from Fantastic Fan that illustrated a new install. Even though the caulking picture refers to the sealant as "silicone", the tube being used is a DAP product.
DAP has two exterior products suitable for caulking/adhesion: 1) Alex Plus, which is an acrylic latex caulk plus silicone and 2) Dynaflex 230, which is a latex product.
As many on the forums will attest, pure silicone is NOT a good caulk nor is it a good product to prevent water from entering the coach. When applied as a caulk, pure silicone tends to have air pockets, which eventually allows the ingress of water.
Pure silicone is great for certain applications, not sealing or bonding anything on the exterior of an RV!
We have used the Dynaflex 230 product and have found it satisfactory for exterior jobs. It does remain flexible over time, an important factor for a moving RV.

[mello mike]

I used Vulkem to seal my fans on my '72 Sovereign and will use Vulkem to seal the fantastic fan on my '58 Overlander.

[jm2]

hi Roger,

do use the FV foam gasket! when you position it under the flange, try to keep it under the flange; else trim it flush before caulking.

NO silicone caulking anywhere on your aluminum Airstream, please! it might be fine for a plastic SOB, but not on your Excella.

instead, Sikaflex 721 is an excellent product, and is most easily available at the "Mother Ship" store in JC, or, maybe even your local dealer.

check the date on the tube; you'd like it to be less than one year old.


these threads may also be helpful to you -

http://www.airforums.com/forums/f455...all-65731.html

http://www.airforums.com/forums/f456...oof-64298.html


best,

(and also in NJ.... )

[pbearsailor]

I'll be the contrarian here as I used grey silicone on mine. Followed the VTS recommendation and also from a Colin Hyde discussion on the Vap. Didn't use the foam gasket and went with pan head screws and flat washers instead of countersunk.

Not sure there's a right answer on this one as you're likely half wrong either way you do it.

cheers,
steve

[Dave Park]

I have used silicone on my Tradewind and had leaks within 12 months everywhere I used it. I then used Vulkem and have never had any leaks develop on metal-metal and metal-plastic bonds.

I used olympics to hold down the fan flange, and I did not use the supplied gasket. I got the tightest fit, and much less vibration passing through to the shell than with the foam gasket in place.

[JackMac]

My sealer of choice for anything on the Airstream is Pro-Seal, a two part polysulfide sealant used in the aviation industry. It sticks to anything, cures to a medium-hard rubber consistency, and is impervious to almost anything. A little pricey for a 3 1/2 ounce tube at $18.00, but as my dad always said: "It only cost a few cents more to go first class". It can be found at Aircraft Spruce, and has to be shot with a sealant gun.

[jdalrymple]

I have used the Trempro 635 sealant on 3 fans and never had a leak. I used a putty knife to spread it all along the frame of the fans onto the roof of the AS, similar to what the factory had done.

[Minno]

If you check out our Little Girl Refurb thread, you can see first hand what pure silicone will do to aluminum over time. I'm sure that tv antenna was up there for awhile, but it ate the aluminum down to a very very thin veneer. I would definitely go with something that is not silicone!

Kay

[bwaysteve]

I recently sealed the interior seams and rivets of my Ambassador with Seamermate (HD $4.99).I spoke with the techs at Amerimax the parent company and this is a non silicone ,self leveling,aluminum gutter seam sealer.It appears to look and has the characteristics of Parbond.Dries to the same type of look.I sealed my restored tailight housings today and will probably use on seams.I have used under all olympic rivets and sprayed water with no leaks.I also checked out member Bob Thompson's posts on this stuff from 6 yrs. ago.I pm'ed him and he said no leaks in 6 years,great product!It applies and stays silver.Just an additional product to confuse you,but easy to find.

[Splitrock]

Originally Posted by bwaysteve

I recently sealed the interior seams and rivets of my Ambassador with Seamermate (HD $4.99)..

Why seal interior? Do ya have some wild parties? What color Seamermate? I'd need blue to match my drapes.

[bwaysteve]

Sealed interior since I was down to bare shell.I was able to see old leaks and corrosion that I cleaned up.Insurance seal inside.I think it only comes in silver.No parties yet,need a couch and a refer!

[polarlyse]

Hey a couple of folding chairs and a cooler. Life is good. What more do you need ???????

WHY WAIT !!!!!

[toastie]

I used trempro 635, no foam gasket. Trempro is a great product both on aluminum and plastic. http://www.tremcosealants.com/indust...tail.asp?id=33

[Splitrock]

Originally Posted by bwaysteve

Sealed interior since I was down to bare shell.I was able to see old leaks and corrosion that I cleaned up.Insurance seal inside.I think it only comes in silver.No parties yet,need a couch and a refer!

You had your inside skin off?

[polarlyse]

OK. It's time to add to the mess. My 2 new Fantastic fans arrived last week while we were camping in the Adirondack Mtns. of New York. Had a great time. When I got home I opened the package and checked out the installation instructions. I ordered the fans from Vintage trailer and spoke to them about the recommended sealer at the time of the order. They said that they use the TremPro 644, a silicone based sealant. They insist that they use it on airstream jobs with good results. So, not being happy with one opinion I called Fantastic. They referred me to someone in Fla. that installs hundreds of fans on AS's. When I posed the question to them they agreed with most on this forum that are of the "no silicone" school. They use Dicor 501, self leveling non silicone. I have a tube of polyurathane sealant. A tube of silicone sealant. And now when I manage to locate it I'll have some of the Dicor. Go figure. Ask 2 people and you get 3 different answers. The only source I've found for the dicor is camping world. So next week I may be near one and I'll get some so when I do the job I'll be ready with it. I think I'll stick with the no silicone crowd on this job. There's no real rush, it's too hot to do it right now anyhow.

Thanks for all the advise. I appreciate all the knowledge floating around ouot there. Please keep it up.

[lewster]

...........but I just can't let folks walk down the wrong path.

You want the skinny from someone who works on hundreds of RV roofs every year and uses cases of sealants, not just the DIY guys who do their own trailer and become weekend experts? (sorry guys, but I use more sealants in a week than you will use in your lifetime)

EVERY major motor home or trailer manufacturer use one of 2 products: Dicor self leveling sealant or SikaFlex 221 one part polyurethane sealant. I see these on virtually every roof I am on, from small travel trailers to Million Dollar motor homes.

YOU WILL NEVER FIND SILICONE ON THE ROOF OF ANY RV OEM'S PRODUCT I don't care what VTS or any other supplier says, USE SILICONE SEALANTS AT YOUR PERIL!!!!! The reasons can be found in many threads on this Forum, so I won't get into that.

Dicor is a good product but tends to show shrinkage cracking in a few years, necessitating the re-application of the product. I do this on a regular basis due to the brutal winter sun exposure in SW Florida.

SikaFlex 221 is a great sealant and bonding agent that comes in colors and once applied, you will never have to touch it again. Only down side to this is it must be mechanically spread (think plastic putty knife or rubber gloved finger) to properly cover the seams you are sealing. Almost any roof penetration should use a layer of butyl tape under the flange unless the manufacturer provides you with a gasket, like Fantastic or all of the roof air conditioner OEMs. In these cases, NO SEALANT of any type is used on the bottom of the device, just around the screw holes and outer seam on things like power roof fans.

Sika Corp. also has a new self-leveling sealant called SikaFlex 715. This comes in white only and for maximum effectiveness, the roof should be prepped with their special cleaner/prep solution before application. It is an expensive combination, but it is the best stuff I have found yet for this application. It will probably replace Dicor for all of my initial sealing tasks soon. It stays more flexible than Dicor and will not crack or shrink.

[polarlyse]

Well, the dasterdly deed is done. At least I hope it's done. A good rain storm will confirm. I used the Sikaflex sealer. I see now why some prefer the self leveling type. The stuff I used was not a self level type. I'm not going to win any contest for neatness but I got them in and sealed the other evening. I had covered them with plastic and sealed it down with masking tape ( a mistake ) in case it rained before getting them sealed. Now I have the baked on tape to clean off. It did not rain. I screwed them down and sealed them Monday evening. It got dark on me so Tuesday evening I finished the inside and wired them up and put the interior trim on. Looks good, works great. The fantastic fan is a nice unit and works as expected and is certainly a lot quieter than the ones I took out. Since they have a much larger fan area they push/ pull a lot more air. Haven't tried out the rain sensor and auto close feature yet.

Overall a nice project and a great improvment. Thanks for all the help and advise. Next I will probably have to tackle my dump valves. The grey water valve seeps and I should probably change them both while I have my hands dirty. Probably wait until spring for that one.