do RV roof vents make a difference?

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mooserider
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do RV roof vents make a difference?

Post by mooserider » Mon Jun 15, 2015 8:17 pm

Given the discussion about solar ovens, uh, RVs on the playa, I was wondering whether the roof vents in the RV would help in letting any of the heat out during the day. I was considering opening the vents and running their exhaust fans at max speed during the day when I'm not there to let some of the heat out, so I don't have to leave the generator (for A/C) running all day when I'm not there (I have plenty of solar power to keep the coach batteries charged while those fans are running).

Is it worth doing that, or will it not make a difference without something like a swamp cooler to make sure the replacement air is cooler than ambient?

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Re: do RV roof vents make a difference?

Post by Sham » Mon Jun 15, 2015 8:24 pm

Keep in mind that the wind can pick up and hit 70mph there. You may get that vent ripped off by the gusts. Even though the fan is on, remember that the playa dust is talcum powder fine, and that will cover everything in a haze of dust.

Everyone has their own theory on how to keep things cool. I tend to stay outside during the day, and only go inside after the sun goes down. It all depends what works for you.

Welcome to eplaya and looking forward to seeing you in the dust in a few short months.

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Re: do RV roof vents make a difference?

Post by dragonpilot » Mon Jun 15, 2015 8:50 pm

Anytime you can get air circulating is a good thing, but in order to do that effectively you have to crack a window or two...otherwise the only thing going out the vent is heated air replaced by more heated air inside. By air flowing thru the RV it doesn't have as much time to heat up...but no matter what, any cooling effect is going to be minimal at outside temps above 95F.

The other thing you can count on that Sham eluded to is the unscheduled dust storms. Crack your windows, turn on the vent, climb on your bike for a playa excursion...and as soon as you're 2 miles away look back and that big dust bumper you see is directly over your RV...with the windows open.

Just button it up tight when you're gone. When you get back open everything up and get that cross-ventilation you so crave.
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Re: do RV roof vents make a difference?

Post by Captain Goddammit » Mon Jun 15, 2015 9:30 pm

I strongly recommend closing everything tight whenever you leave. Otherwise your rig can get trashed by dust storms.
I also recommend locking the door, not so much to keep the bad guys out, but to keep your friends out! Why? They will do you a favor and wash your dishes for you, running all your freshwater into the waste tank, not knowing any better. or use your toilet and shower etc., never intending any harm, but causing plenty.
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Re: do RV roof vents make a difference?

Post by Molotov » Mon Jun 15, 2015 9:43 pm

I have a 4 inch diameter air intake vent in my RV trailer bathroom window that has two levels of filters-one inside and one outside. The roof vent with multi-speed fan-used to blow air out only, has a dust filter on the interior side to catch any ambient dust that might get in. The exhaust fan changes sound if I'm not getting enough intake air, so I can fine tune it. My power roof vent has a rain cover over it that has been tested to 80 mph-so not worried about it tearing off, but it would make a dandy air scoop if it is facing into a dusty wind and I'm not there, so the vent gets closed when I'm gone. I hang an orange streamer from the operating knob to remind me to close it. :lol:

The ventilation system works pretty good-but during the worst 2014 dust storm there was a visible haze inside the trailer. I found an unlatched sliding window had crept open about 3/4 of an inch during the rough ride in from the highway. I cut wood dowel rods to place in window tracks this year to prevent a recurrence. The dowel rods don't affect the function of the emergency escape window, which swings out and up.

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Re: do RV roof vents make a difference?

Post by asr9754 » Tue Jun 16, 2015 12:03 pm

I would not leave my vent or windows open--the dust and wind are just too pervasive and unpredictable.
I put mylar space blankets (99c) over the windows w/ blue painter tape and it cuts down on the solar heat noticeably. Also the space blankets look 100% opaque from afar but actually when you are in the trailer, a bit of light gets thru and you can still see the outside world, which is nice.

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Re: do RV roof vents make a difference?

Post by Canoe » Tue Jun 16, 2015 8:11 pm

Roof-vents and skylights are a huge source of heat.
Any vent can be a huge source of dust too.
Same for windows.
There are a few rare moments on the playa were the air outside is cooler than the air inside (fairly rare), and where there's little dust in the outside air (also rare), where you may have the Perfect Non-Storm where you can open up and get some cooler fresh air inside.
But generally you want to seal all sources of dust (and hot air) coming into the RV, and you want a radiant barrier and some insulation on the windows, roof-vents/skylights.
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Re: do RV roof vents make a difference?

Post by tatonka » Tue Jun 16, 2015 9:41 pm

I only cracked mine open when I was running the Figjam cooler .
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Re: do RV roof vents make a difference?

Post by mooserider » Tue Jun 16, 2015 10:03 pm

My intent was to only open the roof vents when:

a. the exhaust fans were running to push air only out of the vents (not let it in), and
b. using something like a FIGJAM cooler to be bringing cooler dust-filtered air in at less noise and fuel consumption than running the roof air conditioners.

The intent was not to let more dusty hot air in through the vents.

It's possible to have the vents cracked open and still have them covered with foil bubble-wrap.

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Re: do RV roof vents make a difference?

Post by Canoe » Wed Jun 17, 2015 11:18 am

apavlin wrote:My intent was to only open the roof vents when:
a. the exhaust fans were running to push air only out of the vents (not let it in), and
b. using something like a FIGJAM cooler to be bringing cooler dust-filtered air in at less noise and fuel consumption than running the roof air conditioners.
The intent was not to let more dusty hot air in through the vents.
It's possible to have the vents cracked open and still have them covered with foil bubble-wrap.
When running a swamp-cooler, let the incoming air force the hot air inside the RV out through whatever you use for exhaust vents: do NOT have an exhaust fan running. Run an exhaust fan too and you risk getting a somewhat negative pressure which will suck hot dusty air in wherever it can (and aided by the wind). A big blow will overpower air exhausting and will blow outside dusty air inside through the vent. A number of things, like clothes dryer vents, have been used in a number of structures, but always make sure you have a mechanical closed override to secure it closed for when you leave your structure.
It's tempting to leave a swamp-cooler running while you're away (so you have a cool structure to return to), but the risk of returning to a dust-filled abode doesn't make too much sense when you can return and get instant cool dust-free air from the swamp-cooler, which will immediately work to cool you while quickly cooling down your abode.

For venting, people have successfully taped a furnace filter over a roof vent on the inside, taped sealed fully to the ceiling, with a hole carefully poked through for the vent handle. This works for mild winds. A big blow and all bets are off. I always got mine closed quickly whenever wind or a bit of rain came.

Given how much heat comes through roof-vents & skylights (directly and through the frames), it's likely much more efficient to completely cover them over, fully sealed - at least four inches beyond the frames. (For the one over the main bed, I installed the furnace filter over it, open at night when appropriate, covered completely sealed with FSBW during the day.)
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Re: do RV roof vents make a difference?

Post by asr9754 » Wed Jun 17, 2015 1:08 pm

Doesn't matter what your intent is, the dust will find a way! If you're running an exhaust fan to blow out the roof vent, the rv will have low air pressure inside and will literally suck dust thru all the other nooks and crannies in the ststructure. And a proper playa dust storm would well overpower an exhaust vent. Give it a try and see if it works.

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Re: do RV roof vents make a difference?

Post by traceyh » Thu Jul 14, 2016 3:22 pm

We covered our window openings and vents with these cut to size rolls of air filter we bought at Home Depot. That helped filter out some of the dust so we could open a window or two. Still, we got a ton of dust inside the RV.

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Re: do RV roof vents make a difference?

Post by Bayougirl1956 » Wed Jul 20, 2016 7:59 pm

Use a spray bottle to spray the air filters with water. It helps catch a lot of the dust.

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Re: do RV roof vents make a difference?

Post by ranger magnum » Sun Jul 24, 2016 8:24 pm

Ok, first of all DO NOT SPRAY ANY FILTER WITH WATER. Within a short period of time, you will have a clogged and now useless filter. If there is any type of fan trying to blow or suck air through it, you may very well burn out the fan motor.

Like the captain said, keep everything closed. Yea your RV feels like a Betty Crocker easy bake oven. But leave any vent open (fan or not), and it will also become a dusty Betty Crocker easy bake oven.
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