Vent Fan on Roof or No vent Fan? Solutions?

[SternWake]

http://www.amazon.com/Attwood-Blowe...pebp=1435457225842&perid=1CP7P127TCA2EHZXYSFM

+

http://www.amazon.com/Speedi-Produc...sim_200_3?ie=UTF8&refRID=1E7B1AW4KGFJQTSWM89Q

Run the 3 inch piping to suck hot air from the ceiling and blow it elsewhere outside the vehicle.  You could even have a  movable 'snorkle', to suck off cooking gasses

+ speed/noise control:

http://www.amazon.com/RioRand-trade...pebp=1435457415792&perid=0DKDS7GCG10MNJQASDT3

15 khz modulation might make the Fan motor Whine annoyingly at reduced speeds.  Other DC motor speed controllers have higher khz modulation, which might annoy your dog, but will be inaudible to you.  Those links above are  just the first links I saw, not personal product recommendations.

I can't say leaking has not occurred with my Nicro 4" marine roof vent, only that it does not currently leak as I worked out those bugs long ago with some closed cell soft weather stripping.  I do regularly remove the vent from its retainer, and clean it.  Reseating it fully  to compress the weather stripping is required to prevent leakage.

When it leaked the water had no choice but to drip straight down.  It did not creep along the ceiling, thankfully.

 

[2TheStreet]

So what if I don't add a vent? Will I die in my van? lol I see many van dwellers with no roof vents and seem to do just fine. Any cooking I do will be with the barn door and rear door open. Also, I think I'll just get window rain covers and crack the windows.

 

[Optimistic Paranoid]

So what if I don't add a vent? Will I die in my van? lol I see many van dwellers with no roof vents and seem to do just fine. Any cooking I do will be with the barn door and rear door open. Also, I think I'll just get window rain covers and crack the windows.

People who've been doing this for years have learned from experience that they are a lot more comfortable with a powered roof vent than without one.  By all means, feel free to ignore their advice.  After all, the only person who will suffer is you.

But I am curious.  If you already knew the answer, why bother to ask the question  here?

 

[Canine]

I'm in a slide in camper temporarily. It has a roof vent and having a vent on the roof does make a big difference in keeping it cool, but I don't like it. Mine cracked and now leaks- right on the bed! Gah! I gooped it up and now it doesn't open. I use a fan that has approximately 180 cfm and works amazingly well at exhausting the hot air, but when it starts hitting 90F, it isn't starts to struggle. 95 is uncomfortable. 100 is too much for me. If I had more cfm, it would be comfortable enough. I'm not sure how much cfm would be good for my small rig, but I'm guessing 400 cfm would handle the heat I deal with. Moving hot air out of your rig makes a big difference in comfort. I would rather have an adjustable fan that has more cfm than I need. The remote control is an electric drain that I don't need. Powered opening is a great way to jack the price when you don't need it. One feature I really, super-duper like is having a thermostat. This way I don't need to get up during the night to shut it off if it gets too cold.

The fan doesn't need to be at the tippy-top of your van, but it does help. The higher the better. I'm going to mount a Fantastic Fan or Maxx Air with the thermostat in the back on a vertical wall near the top, but not in the roof. I want about 500 watts of polycrystalline solar up there instead.

Leaks suck as they seem to happen when it rains heavily for days at a time when you can't get to it. If you do it right, it won't leak, but I don't want to deal with a leak at all. I hate leaks.

 

[akrvbob]

I'm not a big fan of powered roof vents--I've never had one though. In my cargo trailer I have two roof vents and they really help, I wouldn't be without one.

If you know what you are doing, a roof vent won't leak--it's no big deal. For $40, it's silly not to put one in!!!!

I'm in my van for the summer and it doesn't have a roof vent at all. I find that as long as I use a good fan inside with me, I'm fine. The huge advantage of a portable fan over a roof vent fan is you can set it close to you and aim it at you--that is far, far better!!

If I had to chose one or the other (roof fan or portable fan) I would chose the portable fan. And, you can can get a O2 Cool fan for $20 and stay just as comfortable as a $150 powered roof fan.
Bob

 

[SoulRaven]

People who've been doing this for years have learned from experience that they are a lot more comfortable with a powered roof vent than without one.  By all means, feel free to ignore their advice.  After all, the only person who will suffer is you.

I've been doing this since 1964 and never found any advantage to a roof vent over windows with a fan aimed outwards to pull the air through.

Windows cracked at the top will work just as well as long as you have a fresh air source down lower.  Roof vents suffer from the same problem.  Unless there is a lower fresh air supply, there will be no air movement unless it is forced via a fan.

Due to security concerns, my van is shut up tight when I leave, no windows cracked or open.  When I've had roof vents, I really couldn't tell that they helped at all.  Opening a window on one end and fanning a door on the opposite end a few times, seems to be the most effective solution when returning to a hot van with or without a roof vent.  This will draw the cooler outside air through the van very quickly equalizing the indoor and outdoor temperatures.

If a roof vent malfunctions, either with or without a fan, you can have major problems to deal with.  If a portable fan malfunctions, it is both easy and cheap to toss it and replace it.  If you choose to repair it, it is still a much easier task. ( I just repaired one of my fans with a good dousing of WD-40 and some tinkering, and was very thankful that it was portable and I didn't have a huge R&R job to deal with too.)

One thing I have learned over the years, is the KISS principle is the only way to go.  The simpler it is, the less problems that arise.  Murphy was a very smart man.

 

[SoulRaven]

Leaks suck as they seem to happen when it rains heavily for days at a time when you can't get to it. If you do it right, it won't leak, but I don't want to deal with a leak at all. I hate leaks.

Leaks are the main reason that I will never put a hole in a roof.  Every rig I've had that had vents, or anything else that required so much as a screw hole in the roof leaked sooner or later.

I've also had leak trouble caused by people adding things to the outside skin or doors too.  So far this van has been leak free and I plan on keeping it that way.

 

[GotSmart]

Leaks are the main reason that I will never put a hole in a roof.  Every rig I've had that had vents, or anything else that required so much as a screw hole in the roof leaked sooner or later.

I've also had leak trouble caused by people adding things to the outside skin or doors too.  So far this van has been leak free and I plan on keeping it that way.

I have made a living for years doing both high pressure and low pressure water and gas lines.  I have no fear of making a roof so it will not leak. 

Opening a roof vent on a hot day means the vehicle will not have a lot of super heated air in it if you leave it for a couple hours.  

But I am preaching to the closed minded.  

 

[eDJ_]

I haven't seen this mentioned yet but it builds on that VW Van louver vent.

For years I've noticed "house trailers" have a power vent in the kitchen that has a spring loaded door
and a motor that seems to be switched on as the chain link actuation opens the outside door.

Like so.

I don't know if any similar 12 volt products exist  like this, or could be built out of computer fans
to switch on and off by a thermostatic switch   Painting the roof of the Van white would also seem like a
step in the right direction.

I also have a 12 volt fan that came off a School Bus mounted near my bed to blow air on me.   The switch
is where I can reach it to turn it on or off.  I've thought many a time that a clock work timer that would turn it off automatically would be  a step in the right direction too.

 

[SoulRaven]

My minivan ('04 Sienna) has four drainholes in the back a couple inches in diameter. Removing the plugs, on a hot day I feel a breeze of cool air rushing up from under the van. I'm excited to experiment with using these, still working out the details.

My research yielded a couple relevant write-ups of others who have utilized floor vents in their build:

This one created a "false back wall" in their van so they could open a "back window" generously venting air from under the van while the actual back window remains closed.

A private investigator did two floor venting projects. One used a roof vent fan flipped around, so that both controls and cover were inside the van installed into the floor. The other uses a smaller, noisier, but more powerful blower. 
(Moderator edited link:  http://www.stealthsprinter.com/van-build/ventilation/)

I can see advantages to venting from the floor because there are no holes in your roof and it's more covert, and if you're parked there a while there's going to be cool air to draw from even on hot days. Just something I haven't seen mentioned.

 

[eDJ_]

You may be onto something there Bitty.  You know those Computer fans come in all sizes and voltages.  I've seen some small ones that can move 115 CFM. 

I could even imaging a piece of plastic pipe extending up to the roof inside with a fan in it near the roof to blow hot air down the tube to vent out the bottom and away from the van with an elbow attached under the bottom of the Van.  Something like that rigged up could exchange air with the windows rolled up and as
quiet as these little fans are, I doubt anyone on the outside of the Van would even be able to hear them running.  I think they draw very little power as well.

 

[SoulRaven]

Yipes I didn't copy/paste that link correctly, repeated a saved draft of my post instead. Would a moderator mind fixing it for me? This was supposed to be the first link with the false back wall: http://www.stealthsprinter.com/van-build/ventilation/

 

[SoulRaven]

I could even imaging a piece of plastic pipe extending up to the roof inside with a fan in it near the roof to blow hot air down the tube to vent out the bottom and away from the van with an elbow attached under the bottom of the Van.  Something like that rigged up could exchange air with the windows rolled up and as
quiet as these little fans are, I doubt anyone on the outside of the Van would even be able to hear them running.

It's an idea, though my thinking is more along the lines of using window vent visors to crack the roll down windows of my minivan (including passenger windows) without compromising stealth, and seeing how far I get with the heat naturally rising out when there's ventilation coming in from the floor. I grew up experiencing this concept firsthand at my grandma's house, she had a walk-out basement opening to a covered cement patio with a greenhouse roof, and if ever there was a hot day she simply opened the sliding door below, plus a few windows upstairs, and cool air would be sucked throughout the entire house, sometimes literally making it too chilly on days that were upper 80's/lower 90's. Everyone couldn't believe she didn't have air conditioning.

I'm not certain the concept will/can work as well in a van, but I'm looking forward to experimenting with it.

 

[SternWake]

A 120 MM computer fan which can move 110 CFM, is NOT a quiet fan.  It will draw 0.4 to 0.6 amps to do so and spin at 2100 to 2400 rpm to accomplish that rating.  It can be a high pitched, very annoying noise depending on the exact fan, and their range of quality is profound in these regards.  A company like Noctua has one to ridiculous lengths to have quiet efficient fans, where as one can buy 30 sleeve bearing fans in bulk for less than one Noctua. 


Adjustable speed fans are key, and the larger the fan is, the quieter it is, and the more air it moves at slow speeds.

Silverstone makes several fans with variable speeds, in 120 and 180MM diameters.  The AP182 moves ~62 CFM on its slowest speed, practically silently for 0.05amps.  The Silverstone FM121 moves 33CFM at its slowest speed for a little more noise and consumes 0.08amps.

One can also use a PWM DC motor speed controller on just about any computer fan and this does effect the amp draw as well.  A fan driven 95% throttle will use 20% less amperage than one driven to 100% throttle

One can also control the fan speed with a voltage controller, as long as it can handle the full consumption of the fan at 14.x  input volts, as it will get when driving.

Pushing/ Sucking up cold air from below is not a new idea.  It is a good idea, but for the possibility of exhaust asses entering the vehicle when driving.  A good method for sealing when driving, or when ventilation from there is not required, should be employed.

A fan which can exchange interior air for outside air is more effective than simply moving hot air around inside.  An interior breeze is fine, as long as it in not 15 degrees hotter inside than out .

A fan in the window works better if it is the only aperture on that window. Think Cross ventilation.  2 fans, a push pull scenario for more efficient air exchange.  Pulling air from the shaded side works too.

There also exists the possibility of radiator fans on a speed controller.  These come in Diameters as small as 5 inches, and can be quite powerful, and loud.

http://www.etrailer.com/Radiator-Fans/Derale/D16505.html

And a Speed controller for it:
http://www.amazon.com/Controller-Go...06&sr=8-25&keywords=dc+motor+speed+controller.

Put one of these on the floor with a good hatch/Lid/cover, and then you can crack your front windows to let the hot air out, and you can likely easily get away without a roof vent.

 

[eDJ_]

I'm sure that would work too.  When I open my rear door windows (they tilt out at the bottom) and roll down the front windows a bit I get natural air flow that way too. I should probably invest in some of those window
visors myself.

In the past I've seen small flexible screens about 2 inches tall that are inserted into an open door window and then the window rolled up to trap it in place.  Those with the the door visors would probably keep the bugs out
and allow ventilation with your system.   I would just use my rear window nets over the open windows with those
2 inch nets in the front door windows.

 

[SoulRaven]

But I am preaching to the closed minded.  

You're confusing a closed mind with experience.  I have no roof vents, and no added insulation.  It is now 3:15am and still 90° outside, with 50% humidity.  Inside my van it is 72° and 28% humidity.

I'm about to send my company home to their hot insulated rigs with roof vents.  I'm the only one with A/C so at our 10pm closing time, the three of us hang out in my van because it's the coolest.  Our daytime highs have been running 110-115 degrees, and if it wasn't for my 12v A/C unit, we'd all be dying of heat stroke working in a hot tent all day.

Looks like I'll use 2 blocks of ice, and maybe 1 gallon of gas for my generator for a 10 day fireworks stand gig.  Less than $1.00 a day to stay comfortable is perfectly acceptable to me.  This will be the 4th day of running my A/C 24 hours a day.

I'm actually very open minded, any time somebody convinces me there is a better way, I am always willing to try it, but I'm also willing to give a critical report if warranted too.  I don't play favorites no matter who recommends something.  I call it like I see it, and I've learned a lot from a lot of mistakes.

I don't try to be popular, I try to be accurate.

Cheers!

 

[2TheStreet]

Thanks for all of the responses. I'm just going to invest in a nice $20 fan like akrvbob and Off-Grid mentioned. Some of you are talking about all of this heat but we are back in the 60's here in Ohio. lol I'm loving it. I hate hot weather, reason I moved away from FL. I'm the weirdo that actually loves winter, just hate it that I can't ride my motorcycle when it snows, otherwise, I ride in 35+ degree weather with a smile.

One thing I'm grateful for with this chevy express van is the a/c is cold as ice, literally takes a couple minutes to chill out the van. Also, I don't have windows in the cargo area in this rig which seems to keep some of the heat away.

 

[SoulRaven]

Thanks for all of the responses. I'm just going to invest in a nice $20 fan like akrvbob and Off-Grid mentioned. Some of you are talking about all of this heat but we are back in the 60's here in Ohio. lol I'm loving it.

Totally understandable. That's the way I was too. I'm in Seattle, known for its rain and mild climate. When I got my dark blue van I scoffed at everyone's advice for light-colored vehicles and purposefully parked in the sun to soak up the heat. "I'm doing just fine, I dunno what they're talking about!" I'd tell my friends. Or, "Well it's not like i'm in the south or the dessert" I'd tell others.

As I type this sitting up it is 86 degrees outside. Inside the van, with all my doors and windows open and the sun blocked out by curtains, it's 103 degrees where my head is. Lying on the floor is cooler.

The past couple weeks I've now experienced serious heat exhaustion once, my boyfriend twice. When it gets that hot it's no longer a matter of personal preference or tolerance, it's straight up safety. "Surviving the heat" is no exaggeration.

So, you're the one who knows your weather patterns there, getting a fan for now sounds like the perfect current solution and perhaps that will turn out to be all you need. But I'd advise being ready to implement further measures if it turns out you need them.

 

[SoulRaven]

Bitty,

Try to find some shade to park in if you can. My van is blue too, and shade does wonders.

I currently stuck in a big empty blacktop parking lot with no shade anywhere through the 4th, but luckily I my A/C. As soon as I'm done with this gig, I'll be heading for shadier places.

OG

 

[SoulRaven]

Bitty,

Try to find some shade to park in if you can.  My van is blue too, and shade does wonders.

Twice the past week I've driven for 45 minutes around this area seeking shade and found none- zero, zilch, nada. On top of that my engine keeps stalling out due to what's been suggested as vapor lock, has caused some serious near collisions. Staying in this area means it's possible for me to work on fixing up the minivan, leaving it entirely is pretty risky from a safety perspective unless I go at night after it has cooled down, drive for at least an hour to seek shade further than I did previously with no guarantee of finding it. Hard to find safe places to park in suburbia let alone shady ones. I've been researching it all day googling various maps. Closest possibility I can find is DNR land about an hour away but I'd have to purchase a Discover pass for that, which is vehicle-specific, not sure it's worth it to pay $30 for a year-long pass tied to a van I'm about to get rid of. Plenty of local parks nearby, none of which have any shady spots whatsoever. I'm serious. Nothing.