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2019 ProMaster, 159" 2500
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Discussion Starter #1
I was laying it out where I want to place the vent. Of course it would best suit may purpose to the first area before the real doors. But while I was laying it out (14.5 x 14.5 hole) I was trying to justify myself if this is really the ideal spot. One thing that came to mind, will this hole weaken the heavy truss going across the back that the doors consistently get slammed into. Will I eventually start having alignment problems with the rear doors (I have the high roof)? Can anyone give some insight to this problem? Am I better off going more toward the center of the Van (159")? I'm sure this will reduce the (before the hole is made) strength of this area of the roof. What concerns me is the closing of the doors, which get closed rather hard. I already have adjusted them twice sense I owned the van.

Has anyone notice a difference in their doors that have had the vent in for sometime?
 

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It should make no difference at all. No one on the forum has ever had this type of problem to my knowledge. Make sure you screw it thru the roof into a wooden frame inside the roof to aid in rigidity and give you something to attach your finished ceiling to around the fan.
 

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As long as you don't cut into a roof rib (structural cross beam) or that big box-beam above the back doors, you will be OK. Fans can go anywhere, as long as it's between roof ribs. If you have to climb on the roof, go easy and spread your weight out.
 

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My Maxxaire (standard 14x14 opening) fits between the rear rib and the next one forward with no rib cutting involved.

My Maxxaire does not have the big rain shroud (which may overhang too much to mount the vent in the last section between ribs)

Nice part about the rear location is that it's easier to cut the hole and install from the back of the van instead of from the side. And with the front windows open, air flows the complete length of the van.
 

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Mine is as close to the rear doors as possible, well about 2" in front of the rear beam above the doors. I have the MaxxAir with the long shroud. I also have 2 solar panels ends close to it in that same roof section between ribs. No issues at all. I did build a 1.5" wide wooden frame, 2 inches thick, to match where my finished ceiling would be. I screwed through the roof around the edge of my hole into the frame, and did glue it to the metal skin with SikaFlex. Then dicor over the screw heads, filled the valleys, so it all was level when I screwed the fan mount to the top of the roof.

64296
 

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2019 ProMaster, 159" 2500
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Discussion Starter #7
OK, I worried over nothing. Actually that is a good thing as I already cut it out. Sure glad someone didn't say "wait" LOL.
Thanks again all.
 

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Discussion Starter #8
Yes, I did check against the vent itself and noticed the 14" x 14" - should have come back and fixed that.
 

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Might want to look through the body builders guide and at least be aware of what FCA would like you to do.

My memory is very imperfect, but I think that they actually suggested supporting all roof accessory weights from the rail mount points.

I see a lot of fans mounted toward the back of the van, but sometimes I wonder if it would be better to have the fan as far forward as possible, and solar panels behind it. The reason that I wonder about this is related to keeping air flow from the windshield from coming up under very forward mounted panels.
 

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2019 ProMaster, 159" 2500
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Discussion Starter #11
So while waiting for my vent to arrive, word is it's been shipped, I went ahead and made my top plate and lower plate to deal with the corrugated roof. Have my front and back cut and ready, will cut the sides tomorrow. I'll also add the electric tomorrow. I decided to wait for the vent to get here before I actually put the plates together and in place, just to make sure everything is copasetic.
64351
 

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Discussion Starter #12
Might want to look through the body builders guide and at least be aware of what FCA would like you to do.

My memory is very imperfect, but I think that they actually suggested supporting all roof accessory weights from the rail mount points.

I see a lot of fans mounted toward the back of the van, but sometimes I wonder if it would be better to have the fan as far forward as possible, and solar panels behind it. The reason that I wonder about this is related to keeping air flow from the windshield from coming up under very forward mounted panels.
Harry, before I can see what the FCA would like me to do, I need to know what the FCA is? I will not be putting solar panels on the van, I have six on my motorhome now and the van is for short runs where we just don't need the motorhome. Air circulation will be better circulated by going as far back as possible, I was concerned earlier about structure but after reading what several people put in here and talking to a retired HVAC guy, the best place is the back end. As we are on the subject, using side mounted vents would be out of the question according to him as exhaust would find it's way in. If you are thinking the solar panels would somehow block air, I really don't think that would be an issue. Please enlighten me if I'm off on a strange tangent here.
 

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So while waiting for my vent to arrive, word is it's been shipped, I went ahead and made my top plate and lower plate to deal with the corrugated roof. Have my front and back cut and ready, will cut the sides tomorrow. I'll also add the electric tomorrow. I decided to wait for the vent to get here before I actually put the plates together and in place, just to make sure everything is copasetic. View attachment 64351
Hi @Spiderbobr

It looks like you did a very nice job fabricating those wood top & bottom sections to deal with the roof corrugations. Also glad to hear you cut a standard 14x14 square hole in your roof.

A guy named @Hein on here makes the same top & bottom sections to deal with roof corrugations, except they are made out of “hard plastic” of some type. I know you performed a lot of work to make wood ones, but if wood gets a bit of moisture in it it becomes dimensionally unstable. For the cost of buying Hein’s plastic units might ge worth considering. You should be waterproofing these areas on roof side & when the fans are placed into these corrugated high/low roof pan areas the design can trap standing water (this in conjunction to a wood material can be problematic).

If you do proceed with your wood fabrications, I would suggest you coat it well with a waterproof mould killing sealer product after all cuts are made.

Good Luck with you fan install
 

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Discussion Starter #14
Yes, RV8R, I have already coated them with a sealer, and will again when I put them together. As well as the sealer, there will be a strip under each (where it meets the roof) of Eternabond Roof Sealent, acts like double face sealant. After the install, I will cover with Dicor all exposed areas to the roof. I'm not worried about it rotting or leaking. My motorhome roof is layered with plywood and it's holding up. And, I have the templet I made to make another if I decide to change it out. I just can't pay $75.00 plus shipping for something I'm capable of making. I can put that money toward another item I need. Don't get me wrong I thought about it, his product looks fantastic. Has the radius on the bottom flat on top (as I did) for mounting, and it looks great! And......it didn't (I don't imagine anyway) take almost 4 hours to cut my project out of hardwood, when his, good minutes. But I'm in no hurry. If, and as I said I don't think mine will leak or rot, but if it does, he will be the first I go to. OH, did I tell you mine cost $3.75. The sealing tape and Dicor I would have bought even for his.
 

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While looking for nonexistant relay or harness diagrams last night, I came across this. Basically, they're just reminding us that it took a lot of effort to cut out the cool stuff from the Ducato, and they don't want us cutting out any more. Haha.
(And let me know if this attachment arrives sideways. My sent attachments are all anti-clockwise 90°)
64360
 

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Yes, RV8R, I have already coated them with a sealer, and will again when I put them together. As well as the sealer, there will be a strip under each (where it meets the roof) of Eternabond Roof Sealent, acts like double face sealant. After the install, I will cover with Dicor all exposed areas to the roof. I'm not worried about it rotting or leaking. My motorhome roof is layered with plywood and it's holding up. And, I have the templet I made to make another if I decide to change it out. I just can't pay $75.00 plus shipping for something I'm capable of making. I can put that money toward another item I need. Don't get me wrong I thought about it, his product looks fantastic. Has the radius on the bottom flat on top (as I did) for mounting, and it looks great! And......it didn't (I don't imagine anyway) take almost 4 hours to cut my project out of hardwood, when his, good minutes. But I'm in no hurry. If, and as I said I don't think mine will leak or rot, but if it does, he will be the first I go to. OH, did I tell you mine cost $3.75. The sealing tape and Dicor I would have bought even for his.
Great !!

Sounds like you are aware of the issues & have made your decisions. I understand the cost/benefits you stated & every DIYer must make their own choices.

I cut out my 14x14 roof hole where I did not need such “corrugated” strips ( best location for easy install & less chance of leaks, but not necessary the best place for the fan depending on floorplan etc). Not the best location for everyone. I was not concerned with removing that roof metal in regards to the structural integrity of the van roof.
 

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Harry, before I can see what the FCA would like me to do, I need to know what the FCA is? I will not be putting solar panels on the van, I have six on my motorhome now and the van is for short runs where we just don't need the motorhome. Air circulation will be better circulated by going as far back as possible, I was concerned earlier about structure but after reading what several people put in here and talking to a retired HVAC guy, the best place is the back end. As we are on the subject, using side mounted vents would be out of the question according to him as exhaust would find it's way in. If you are thinking the solar panels would somehow block air, I really don't think that would be an issue. Please enlighten me if I'm off on a strange tangent here.
Hi, sorry for the acronym.

FCA is Fiat Chrysler ( something )

Here is the link to the body builders guide site:


__

For me personally, I would always have air conditioning and probably skip a roof top fan, but that isn't the usual method found on these van forums.

I am not worried about solar panels blocking air flow for the fan or a/c.

When you are out on an open highway, even just parked on the side of the road, winds can easily be 50 - 70 mph. Even faster in some states.

Add on to this driving 70 - 80 mph. This wind is being deflected by the windshield and blown sort of vertically UP. If solar panels are mounted too far forward (not sure of exactly where) this can be quite an uplifting force on roof attached panels.

I am just suggesting to think through these wind force effects as you mount things up there, especially as the panel mounting starts to get close the forward roof curvature. If the fan is in the front area, that sort of forces the panels to be far from these curved areas.

Just kicking around some ideas.

Harry
 

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Hi, sorry for the acronym.

FCA is Fiat Chrysler ( something )

Here is the link to the body builders guide site:


__

For me personally, I would always have air conditioning and probably skip a roof top fan, but that isn't the usual method found on these van forums.

I am not worried about solar panels blocking air flow for the fan or a/c.

When you are out on an open highway, even just parked on the side of the road, winds can easily be 50 - 70 mph. Even faster in some states.

Add on to this driving 70 - 80 mph. This wind is being deflected by the windshield and blown sort of vertically UP. If solar panels are mounted too far forward (not sure of exactly where) this can be quite an uplifting force on roof attached panels.

I am just suggesting to think through these wind force effects as you mount things up there, especially as the panel mounting starts to get close the forward roof curvature. If the fan is in the front area, that sort of forces the panels to be far from these curved areas.

Just kicking around some ideas.

Harry
Other than the relative airflow itself (velocity) the aerodynamics the drag forces are primarily 2 types in relationship to “relative airflow” or “wind” if you like. I am referring to angle of attack & airfoil (Bernoulli’s Theorem) (both cause lift / or negative lift & drag). Multiple Edited paragraph ; (The foregoing paragraph is tragically worded, so I hope it translates into sense)🙄

If I believe the aerodynamic characteristics chatted about of this forum in relationship to the coefficients (& I do trust posted numbers as I do not own a wing tunnel & I have calculated my own fuel milage & it makes sense with the fuel economy), then if I were to place solar panels on my roof I would want to design a leading edge deflector that sealed airflow from the corrugations of the PM roof forcing the air over the solar panels. The idea would be to “seal off” the underside of the solar panels to the “relative airflow” while driving. Without wind-tunnel testing this is only my theoretical mind pondering.

In short, I would want to “ramp” the airflow from the PM roof over the solar panel. In my mind the best location for that (which is impractical) would be right at the transition of intersection of where the roof plane meets the angled windshield plane (Just increasing the height of the windshield plane The 2” or so required to flow the relative airflow over top of the solar panels.

This might be good for fuel economy. I have not sorted it out in my mind yet. It might be bad for heat gain under solar panels. The corrugated roof which is inline with relative airflow may contribute to the pretty decent “slipperiness” of our PM. If I ever do solar, I will design, build, & test my theories.

the picture to describe the above (yellow is the solar panel / red is the airflow deflection I am trying to describe - this would be sealed airtight to the PM roof “leading edge”). Sorry for the “stickman” iPad finger drawing as it is the best I can do without a pencil & paper. NTS
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