It seems like one of the first rites of passage in the van conversions we have seen is installing the fans. It is often the “first blood” of cutting into your new precious van. Eeeek. Well, here is how we took on installing our MaxxFan.
Note: The roof can be dented (ask me how I know), so we used a 2″ piece of hard styrofoam insulation we had laying around to kneel on from then on spread out my substantial weight.
First, we decided on the position and taped off the area:
Then checked to make sure that things would work out inside:
Cutting the roof
Next, we test fit the mounting ring that came with the Maxx Fan. Note that it is white in this picture:
Getting a good seal
Since the ProMaster roof is corrugated for strength, which is great, but that makes it a challenge to install a fan that is designed to go int a flat roof — which is all of them. Heim makes a great adapter and sells it on eBay.
Many people call this a 3d-printed part, but actually it is milled from a kind of expanded plastic. It works well and is nicely made. Many folks use butyl tape to seal the adapter to the van. These are also the same folks that then use a secondary sealer over the top of everything.
I asked myself if the butyl tape is doing such a good job, why the additional sealer? Well, I do not think that butyl tape is a very good solution. I think it is cheap and that is why it became standard on the cheap RVs of old. Butyl is lame because it does not have strength in tension (like a glue) and also does not have compliance to spring back into position if something flexes.
So my approach is to use an automotive grade black SEM seam sealer to securely glue and seal the Heim adapter to the roof:
We used plenty of clamps to make sure that everything was flat while the seam sealer cured:
Interestingly, when I went to remove one of the bottom clamps, the seam sealer had glued the foot of the clamp to the body metal, and I was able to hang from that 1″ diameter glue bond for some seconds. This SEM seam sealer is good stuff!
So, if I have sworn off butyl and the SEM is pretty much permanent, how can I seal the fan bezel to the Heim adapter? The answer is this closed-cell foam tape. It is closed cell, so water will not seep through it. It is very soft and so compresses down to “nuthin’ much”, but it is resilient, so it will expand as needed to keep the seal over flexing and vibration.
We made three passes around the fan. To make sure there is no leak between the ends of the tape, cut the ends about 1/4 inch too long, then put the ends together and carefully press them into place so that the ends press on each other:
Next pass, staggering the joint:
And the final pass:
Securing the bezel to the roof
We then used stainless steel screws through the fan bezel (now painted to match the van) through the Heim adapter (pre-drilled) then through and threaded into the van body metal.
To seal around the screws, I liberated the sealing washers from some similar-sized steel roofing screws:
Time may prove me wrong, but I believe this sealing approach will not require the slathering of additional flex seal sealer over everything.
Securing the bezel on the inside of the van
My son has a 3-d printer, and helpfully printed out the reverse of the top adapter to give us a flat surface on the bottom of the fan.
You can download the 3-d files here.
Note that we did not use the exterior adapter ring made by 3-d printing (we used the Heim adapter), we only used the interior one, which should not be exposed to the weather. We did test fit both the interior and exterior pieces, but we do not know how well they will seal or how well the 3-d printed material will hold up to the weather and automotive environment. Use at your own risk.
Since the 3-d printer bed is not large, this bottom ring had to be printed in several parts. We used Gorilla Tape to hold these together during the install:
Attaching the fan to the bezel
Once the rings are installed, 4 screws attach the fan to the ring, and the project is done:
We hooked up 12v to see if it all works. Everything tested out OK: