Keeping the Dust Out

Funky trailer, I bet that's cosy.
Can't think of anything very clever, vents usually cause air to be drawn out.
Maybe you need to make a model and stick in in a wind tunnel to see the high/low pressure points, then make a big vent at a high pressure point with a filter so clean air can get in.
In a nutshell, make it easier for the clean air to get in than it is for the dirty air.
here in the UK I have the oposite problem...I have 1/4" of water in the boot (trunk) of my Nissan Micra getting in from somwhere...maybe I could fill it right up and keep fish in there for snacking on.
Del

My thought is you'd want to mount the intake as far away from the car's exhaust as possible. No sense pumping your comfy little love-nest full of noxious exhaust odors or worse...carbon monoxide.

I'm not particuarlly recommending it, but one place to start might be Grainger. They sell a variety of small DC blowers which might work (part #3FRG5 is the sort of thing I'm thinking of). One thing to keep in mind no matter what blower you choose is that it will be critical to well filter its air intake (and keep that filter clean). Otherwise your current incidental dust problem will pale in comparision to the thick coating you'll have!

And Del...

Don't ride those poor little fishies around in your boot. They'll get car sick.

Besides, how did a cat get a driver's liscense anyway? I thought Toonces was the only cat who can drive a car.

http://www.wired.com/images_blogs/autopia/toonces2.jpg

Our guest has a good point here. I suspect that the leading high air pressure areas around your trailer will be precisely where your vehicle's exhaust will be dumping. Particularly since your tow vehicle is taller than your trailer. You might consider an air scoop on the top of your trailer. Regardless of where you penetrate the trailer, you will have to consider not just dust entering but all forms of foul weather possibly entering.

I remember a plumbing friend of mine that added a three inch diameter PVC T fitting to the top back part of his work van. This T was aligned so that the slip-steam would flow through the top of the T and Bernoulli provided a pressure drop that vented all of the nasty fumes from the last job out of the van. He did briefly experiment with this by first blocking the front of the T off, but not enough vacuum was developed to save his nose. When he tried blocking the back of the T (making a scoop) the air being blown in while driving did precisely what he didn't want, but you do.

Simple? What is more simple than an unpowered hole with piping that directs the airflow around the trailer to be useful. My approach don't need no stinking electricity. Don't need no stinking badges either.

True...but will you be travelling fast enough down a dirt road to make a filter restricted vent pressurize the cabin?

Simple, and effective. Gotta love a vacuum (even if nature abhors it).

You do need to be sure not to suck up exhaust fumes.

Drew

And if it doesn't work, he's got a vacuum cleaner to suck up the dust.

Exactly!!!

Besides, you will need a vacuum for dirt tracked in anyway. As for how long it will last running, I would spend more on a higher quality unit so I didn't have to worry about it wearing out too quickly.

I know in a small travel trailer space is at a premium, but if you are set upon building a unit with a 12 volt motor you could look into the dust collection systems used in the woodworking industry.

Drew

OK,

This may sound radical, but why not plumb the exhaust into the trailer and use that as your positive pressure.

The vehicle looks to be new and they don't pollute they way my '55 Chevy did, so think it over.

I assume no one rides back there when you are travelling.

You can call me crazy.

I don't think even Dr. Kevorkian would like this idea.

Well....hmmm....I think that the residual gasses would probably make it so I wouldn't care if there was dust inside. That's because I would be either high or dead....

No. No. No. You've gotta air it out before you turn in for the night. Surely you don't let people ride back there when you're driving down the dirt roads.

_{Never mind. It was a dumb idea from the start.}

I suppose duct tape is out, too.

I've actually tried duct tape. We were driving on the "Discover Oregon Trail" that's an off road trip that spans 400+ miles diagonally across the State of Oregon, all on dirt, gravel, rutty, forest service roads. The dust was terrible so I firmly duct taped around the side door, the galley door and (closed) roof vent. The trailers interior still had a coating of very fine, powdered sugar like dust....everywhere. I've looked for possible inlets elsewhere such as fender wells, the floor etc. Everything appears to be sealed tight. That's why I'm going for the pressurized cabin idea.

Picture, if you will, a small box on the front of your trailer just large enough for the 12V fan. From this box protrudes the snorkel, a 1-2 inch dia. vertical tube that terminates in clean air negating the need for a filter, perhaps. Of course the tube would be removable if needed. And reversing the fan gives you a vent when camped. In camp, it'd make a cool flag pole, too.

Hey, it's better than CO.

Is this a plug for Hydrogen fuel system too?

I'm at a loss as to how you could possible make such a connection.

Try to keep the trailer cool before you take a country tour.

Just vent it, so it´s coolder than the outside temp. because if it´s hot when you start the triler will be colder when you drive an then the air will suck in the trailer.

Just a guess, from my side

What? Nobody likes my idea of a vacuum cleaner? It already has built in filtration that you can change readily, they have 12 volt versions.

I thought it was perfect! Here is one that is a blower too so you can use it to fill inflatable beds or water toys.

Drew

" Nobody likes my idea of a vacuum cleaner?" Too practical. No elegance. Sorry.

There is elegance in simplicity!

Drew

Yes, there is elegance in simplicity. But ultimately it's up to the OP what system will use a new or existing hole in this trailer. I do wonder though about the service lifetime of a wet/dry vacuum. Your idea will push more air than any proposed other approach and does already have a dust catcher. Without knowing how much leakage happens its hard to say which approach will be needed or is efficient.

Pretty easy test for it though. Put an exhaust vent and measure outlet when vacuum is at full blast. A simple flapper on the exhaust will show if there is much pressure when vac is on. I would assume you won't see much, the real test will be driving down a dusty road to see if dust accumulates.

Drew

I love the western deserts and don't spend enough time out there. I know what it's like. That Toyota pickup in my picture is my one person desert camper. And yes, dust does get into it around the tailgate mostly.

Drew's 12volt vacuum cleaner looks neat. But don't be too surprised if its life is only a few hours especially in hot continuous duty operating conditions.

A lot of the older (like 1960's and 70's large sedans) have fairly large heater blowers. You'll probably have to butcher the heater to come up with a usable outer scroll housing. This would give you more air flow but less pressure than the vacuum cleaner.

Next time you're out on a dirt road with your wife or someone else have them drop you off at roadside in a place where you can get back a hundred feet or so with your camera. Have them drive your rig (with the trailer) up the road, turn around and drive past you while you photograph the dust dtreem theat the car-trailer combo kicks up. That will likely tell you the cleanest place to put an air intake for positive pressure or bernoulli effect cooling. If an intake a large filter that you can easily clean like the air filters the serious off-road guys use on their engines might work. Another trick is to tape pieces of yarn to the front of the trailer so one of you can watch the airflow in that area while the other is driving at various speeds.

I do like the idea of duct tape. But that can get to be a pain after a while, especially if you like to use the trailer for lunchtime rest stops.

Another thought (if you're a crackpot tinkerer like me) is that you may look into building a small VAWT (vertical axis wind turbine) and generator to mount on the top front of the trailer and generate 12 volts needed to charge the battery that drives the inside fan motor. That same fan placed over the sleeping area can provide comfortable air flow on those warm desert evenings before the inside of the trailer, especially the bedding, cools down from the day's heat.

Ed Weldon

The vacuum cleaner motor is cooled by the air flow. Unless there are significant leaks in the trailer, flow will be significantly reduced. Also, it is designed for intermittent, not continuous, duty. Both factors will lead to premature failure.

Get a vacuum cleaner and use it to slightly pressurize the closed trailer. Use a length of hose to give you isolation.

Then get a water bottle with a little foamy making dish soap in it, dilute it suitably. Then spray it all over the bottom as well as the top and look for places where bubbles form.

My guess is the bouncing on the road make the whole thing like a bellows and it compresses and exhausts, decompresses and sucks, as you go down the road. Sucking air/dust in/out with every bounce.

A small 12 volt computer fan that runs off the car voltage or a solar panel with a battery for night runs could be made to give a slight positive pressure to the trailer to discourage inwards migration of dust. Of course, a good filter would be needed on the intake. You could probably make something up for a few $$, or this cannot be the first time this problem has occurred. Google finds this

http://www.google.ca/#hl=en&q=trailer+%2Bvent+%2B%22positive+pressure%22&meta=&aq=f&oq=trailer+%2Bvent+%2B%22positive+pressure%22&fp=7310e1b076ed5f89

Hello Ron,

Your question and my comments are giving below:

Where would the best place be to mount the intake? - Vertically as high as possible. Dust size decreases with height ie. your filter life will be more if intake is at elavated position and vice versa. (Consider maximum height permissible by rules and fouling with overhead wires / objects etc if any). Some kind of Snorkel arrangement / a simple PVC pipe would also serve the purpose of intake manifold.

Underneath? - Never. Maximum dust will be in this area.

On top? - Recommended.

In front or back? - Preferably, Back of the tow vehicle, especially facing towards Teardrop.

Besides, I feel that its is better to identify the leak points by pressurising the Teardrop from inside if the application is so critical & fix them before installing pressurizing device so that device capacity will be within limit.

Hope this will help.

Limbkar

I like the ideas about actually fixing the problem instead of creating more. They use this in the camper manufacturers in the US. Put pressure one the trailer and check all the windows, doors, vents and seams with soapy water. The leaks will show up and then you can fix the problem.

How about a HEPA grade room air cleaner plugged into your electrical system while traveling. It might suck up the dust as it enters the trailer before it settles on the furniture. You'll have to clean or replace the filters on a regular basis. I'm sure there are some 12 volt versions out here or use a converter for a 110v version.

Put a hitch on the front of the truck and push the trailer ahead of the dust.

Let's see, camping the Oregon trail on dirt roads and you have dust in your equipment?? NASA might say that is what you should expect. My father would say that it would be like doing it along with the first travelers. My mother would say if you are going to have sex on the beach, expect sand in you hand.

My answer to high desert road dust has often been to drive slower and enjoy the scenery especially on graded roads that get like a washboard in places. Of course there are the low sandy spots where driving through fast is the only way. I do recall a stretch of the old pony express route on the south end of the Ruby mtns in eastern Nevada where fast was the only way. You don't want to try that particular place with your nice little teardrop. The only way my 2wd Toyota got through that one was because it was a moderate downhill reach most of the way (about 2 miles).

Ed Weldon

A roll of 2" painters masking tape (blue, easy release), could be applied quickly prior to and removed quickly/easily from door seams after, traveling the dusty road.

Marginal help as the 'van will be fitted with all these holes in the floor with insect grade wire mesh over them.....

I like the teardrop idea and if it was mine I would research and or try these

#1 Full width across rear bumper low mud flap on tow vehicle

in an attempt to route dust from car wheels outside of trailer footprint
this dust is usually on the rear window of todays cars
Todays suvs are not teardrop shaped like the 1949 cars or trailers
and they all have a square back end and are always covered with road dirt
and if you have an oil leak it lands on the back window too
I'm sure if you watch you'll see massive amounts of dust
hitting the front of the trailer and a full flap might reroute the dirt
and prevent positive dirty pressure on the front of trailer

#2 Wind deflector to force air down on car rear window

My old explorer had an aftermarket wind deflector at the back
of the roof luggage rack to deflect (clean) wind down on rear window

#3 Stick on vortex generators (for product names check google) are used
on semi trucks and motor homes and aircraft wings

If you have a negative pressure while towing vortex generators will
reduce the vacuum on the rear of the trailer and the whipping
(which you may have) and reduce swaying compensation wear on stirring
and impressive mileage increases they are also used on aircraft wings
Truckers stated with vgs the trailer pulls straight as a string with
large savings on new front tire replacements and stirring gear wear
Vortex generators can also improve turbulence on your tow vehicle to reduce
negative pressure on tow v and positive on the trailer front
You stick them on yourself up the side and across the top
and no I don't sell or work for these companies

I hope I have helped
John

All that is needed is a vacuum cleaner hose between the towing vehicle and the trailer.

The pressure provided within the car from the heater or air conditioning unit must escape somewhere, if the windows are kept shut and there is a flexible pipe to the trailer the pressure will be passed through to the trailer, escaping through the small gaps which were sucking in the dust.

As the atmosphere in the trailer will be as that of the car, should you happen to give a lift to a bunch of chain smokers you will have to sleep with the foul air.

Simple ideas only come from a simple mind.

I'm back and after looking at your picture I see a roof vent on the trailer
I remember from my trailer pulling days the roof vent always leaked air even when closed
some times while inside just high winds would whistle through the roof vent
Basically it worked like a check valve to relieve pressure even when closed
By design or accident I don't know
But my trailers were high profile with roof vent out of blowing dirt from tow car
that could be a very high vacuum generator at road speed

If air goes out it has to replaced from somewhere

If that is the case creating a positive cabin pressure with electric blowers might
be defeated with the roof vent acting as a check valve with a vacuum on it
at road speeds

If you want to get high tech find a friend with ultrasound leak detection equipment
used in the refrigeration, pipeline trades and roofing leak detection (big $$$$)
A transmitter can be placed inside the cabin and the receiver indicates the leaks
on the outside or if a positive pressure can be applied and the ultrasound is detected
as the air whistles through the cracks
This would be a static pressure test only
But everything changes when aerodynamic drag inters the picture

I wouldn't want to be called to testify in a lawsuit about vehicle gasket leaks
I know one auto lawsuit was settled on a leaking T top with the judge
riding inside the vehicle through an automatic car wash to see if it leaked
and it did
An automatic car wash might help you if you could get the trailer inside? LOL

My interest in helping you prompted me to return to the air tabs (vortex generator)
site to watch any new videos about improving aerodynamic drag on semi trucks
and helping prevent dust entering through the back trailer doors
and to my surprise one corvette owner claimed 3 mpg increase with vgs placed
under the car on the belly pan and across the top near the rear window
Can a stick on vortex generator improve drag ratios on a vehicle that surely
has had fortunes spent on it for drag reduction research?

I'm here to learn

Thanks for helping me getting the old rusty brain wheels spinning
John

Interest, your trailer is aerodynamic. Bear with me this is slighly off-topic.

This reminds me of an issue reducing the boundry layer on a wing and increasing a laminar flow over the surface by using micro penetrations (Your Leaks) that basicly pulls air in reducing turbulance. But the air has to be exhausted.

How are the seals on you windows, or can you seal off you air vents. (VENTS HAVE TO BE OPEN WHEN OCCUPIED)

The air inlet vent size would have to be substantial enough to create a positive preassure inside, situate the vent high off the ground and preferably in a stream of high air flow to increase the air flow pessure into the trailer. you would need a large capacity foam or paper filter of sorts and an assist fan to keep pressure up while you are traveling slow when there's no "air ram" to help but speed is fast enough to cause dust to lift. you would need to create a dorade box to exclude incoming rain etc ( http://en.wikipedia.org/wiki/Dorade_box ) . I suggest using a air fan from an automobile as they have some speed selection options and are designed to run continuously and are pitched for exactly what you want to do.

Basically you would want to mimic your car's ventilation system with all the windows closed and the fan drawing air from the outside of the vehicle and preassurizing the cabin.

If active pressurization is desired I'd suggest looking at the Jabsco ventilating fans.

http://www.jabsco.com/products/marine/ventilation_blowers/index.htm

The 105 CFM DC fans are used by the aforementioned off road racers to keep the dust out of their helmets and to keep themselves cool. One fan is usually enough for both occupants. Can source them from marine vendors 'raw', or can source them from someone like McKenzies with a paper filter and spun aluminum shroud attached to the inlet. I tried to find one so that I could link it direct, but didn't have much luck. I suggest calling them as they're super helpful folk and will have this component.

HTH

First question is how often are you willing to either change or clean a filter?

Heavy trucks designed for off-road use incorporate the engine air filter as the first stage of the cab air filtration system backed up by an activated carbon and or HEPA type finisher.

Recommend use of 12v duct fan inline from the filter mounted on the trailer fed by power from the tow vehicle, put a toggle switch on dash.

In our off-road vehicles an racing buggies etc. we used K/N washable filters and Parker Pumper helmets

Ron,

Have you found the floor vents Andy has referred to?

Good point.

Furthermore, not only do they need sealing while running (and open when actually camping!) but you may find a whole lot of dust already collected and INSIDE the 'van, that needs to be removed before sealing for thenext dusty drive.....

These vents are often hidden away and not easy to find.....

It struck me that there is maybe a vent type that you slide a piece back and forward to seal or open that may be still easily accesible from above or below....

Although these are metal:-

http://www.inbrass.co.uk/acatalog/Closeable_vents.html

I would recommend plastic ones for "Road" usage.....but they should give you a good idea of what you need. Do not forget the fine mesh to keep out insects (and boulders)

There are no floor vents. The entire inside is a wall to wall queen size mattress. The only vent is in the ceiling which is kept tightly closed while towing on dirt roads. There is a galley in back with sink, 16 gallon pressurized water system, propane stove, ice box and drawers and shelves for storage.

The inside does have a propane furnace, DVD/TV/mp3/CD player, LCD lighting etc.

I surly appreciate all the suggestions and will try some of them for sure.

Examine the underside of the floor, I think that you will find at least an opening for the heating, maybe one for a fridge....they need to be closed off while travelling.....

A little OT here, why did my first post get rated as OT? Am I to conclude that the goal here is not to somehow pressurize the interior of the trailer to reduce/remove the dust infiltration? Perhaps my suggestion was to simple & practical?

As to using a K&N filter, Only do that if a very light coating of light oil on everything inside is acceptable. There is a reason that hot wire MAF's have trouble with K&N type filters. BT, DT....

As far as any trap doors in the floor, to the best of my knowledge that is not a requirement anywhere in the U.S. I've spent a fair amount of time in mfg'd trailers and in home builts and I can not recall ever seeing such a door/panel in any of them.

I do believe that the 'van is possibly of European manufacturer (could be wrong there!) and all European 'vans must have these air vents in the floor with a fine mesh over them.

While cooking (using gas) the ventilation in the roof must be opened.

It is possible that there are no floor vents if it follows US regs, as I have no idea what US regs require.......

But if everything is sealed, how does the dust get inside?

Andy, Our Teardrop Trailer is a "Camp-Inn" made in USA. All cooking, ice box etc. are in the galley outside of the sleeping area. There are absolutely no floor vents. Yes the trailer is sealed very well BUT dust still makes its way inside. For example, our tow vehicle is a Nissan Xterra. It is so tight that when we close the doors, we feel an instant of pressure in our ears. Regardless, dust makes its way inside the Xterra. We don't mind the dust in the tow vehicle but dust in the sleeping quarters in the trailer is a different story. I guess I need to make it clear. We tow this trailer sometimes for many hours on dusty roads. I'm not talking about just a few minutes. That's why I want to pressurize the inside of the trailer while on those dirt roads. Because the dust is getting in, that means that there must be some microscopic entry points that I can not find. They may be microscopic but after several hours, a lot of dust will enter the trailer. So, by pressurizing the inside, those microscopic entry points will have air blowing outward so the dust will not enter.

The advice to take several pictures, from a suitable distance, of the truck and trailer going down a dusty road at your normal speed is an excellent one. I can vouch for how illustrative this can be. I learned that lesson watching the Land Speed Racing on El Mirage Dry Lakebed. Good and poor aerodynamics were made obvious by the dust.

Once you have those pictures, picking a location for the air inlet will become much easier. I suspect that you will still need a filter, but by placing it's inlet in "Clean Air" you'll reduce the amount of grit that it will need to filter out.

The most ideal filter will be one designed for the environ. Those made for off-highway vehicle engines would seem most appropriate to me. These can be found on Donaldson's web page: http://www.donaldson.com/en/engine/air/chart.html and likely sourced from a real auto parts store like Napa.

For positive pressure I think that you are looking at needing a ventilator fan. Those made for boat engine bay ventilation seem to me to be the best fit for the job.

Hey, Friend what a nice sharing i like this, yes you are right, Air ventilator pushes the dusty and hot air out of your workplace keeping the workplace sage and cool.

I mentioned a way, elaborating upon what you yourself said, to do that, using a fan and filters, you could pressurize the 'van.....

But you must not forget that your trailer, if it has gas heating, has to let air in to be burnt - somehow! You must identify how......you MUST get under the 'van with a torch and search. Until complete, I do not see how we can help you much further......

Furthermore, the teardrop forms almost an aircraft wing shape, so air pressure will be low over the roof and high under the 'Van. This alone will suck dust from outside through every tiny hole underneath, even if the heater does not need one (but I believe that it does!).....

The so-called "Tear Drop" trailers are seeing a rise in US popularity and frequently are owner-built. I only know of one mfg of such trailers, though I'm sure that there are more. This is that mfg's trailer, as re-configured and sold by a Overland oriented firm: Adventure Trailers Tear Drop

Likely the largest supporting forum for any "TD":

http://www.mikenchell.com/forums/

If it truly is the TD that I suspect that it is, cooking occurs under the rear opening hatch. The interior is reserved for sleeping and storage. It has no cooking access.

Any system you use that involves filters, will be a pain in the a**. Once they load up with dust, they quit working. The fan will eventually burn out. Filters can be expensive. Even if you can come up with a "positive pressure" plan, what happens when you encounter other vehicles on the road. You could be following someone who is kicking up a dust storm.

ronseto,

The filter I recommended #47 would require a month of daily running in a dust storm to clog, it's what they're made for and the probability of the OP driving behind another vehicle is why I posted.

I use a gauge to easily discern the filters usefulness and we knock the dirt out and with compressed air too. We've found that a cleaned slightly dirty filter filters better than a new one. Yep a new filter cost about $35 but the OP could likely use one for a couple seasons before replacement and cleaning once a month is not so bad, These filters are designed for the high air flow of 12-18 liter engine.

On bottom of the filter cannister shown is dimple vent to drain water and dust etc..shiny SS

Well I'm back and I hope you're still reading this mountain of replies
from the many good people trying to help as I have one more that is very important
I went to the builder's website and it's very informative and I hope
you have asked them about your dirt problem
but while looking at the option pictures while searching for possible air leaks
I could see many accessories mounted on the outside skin that could
be leaking as in running light fixtures, door / window gaskets, spare tire storage
electric entrance, etc and the last but the most important is and you said you
had one in a previous post the propane heater
I looked at the picture of the front of the trailer on the options page
and I have to say it scared the pee waden out of me!!
You need to have that heater checked by a factory authorized service center
for a burnt out or leaking heat exchanger

The picture states it has an intake and exhaust outlets on the front of the trailer
which means it has a sealed cumbustion chamber but if that chamber is leaking
it could be deadly and going down the road it's located in the highest pressure
and generated dirt area of the whole trailer

The heat exchanger may be burnt out or just cracked and the road vibration
or tongue and frame flexing may open a temporary crack at road speed
If it was mine I would expect to see road dirt built up there inside the intake/exhast
after a long hard pull on a dirt road every trip and if it wasn't did it go inside the cabin
through a failed heat exchanger?

Heat exchangers fail please call the furnace mfg or trailer mfg
They will listen with all ears when you mention a failed sealed combustion chamber
that is possibly allowing road dirt to enter the trailer
Not all previous owners get notified when a mfg has a recall on failed heat exs
They can tell you more and it might save your life

John

picture of trailer furnace option website link here tinycamper.com/options6.htm

Ahh like this?

Have you got one Ron?

If one looks at the original picture posted, those vents are visible.

I want to thank everyone for their comments which ranged from some very good answers to my original question to dire death warnings. All I originally wanted was some suggestions on a good way to pressurize the cabin of my teardrop trailer to keep the dust out. Somewhere along the way the topic changed.

To those who want to know. Yes. I do have the heater option. Yes I know about Carbon Monoxide poisoning. Yes. I was aware of the connection between the inside and outside heater vents and yes I did tightly seal the heater vent both inside and outside to try to stop dust entry. Also, there are absolutely no floor vents with screens. The inside of the teardrop is wall to wall mattress. All the sealing of potential inlets didn't make any difference. The dust is coming from somewhere else.

I will try some of the ideas that were posted and give an update after our next off road trip. Thanks to everyone, Ron

I look forward to hearing the conclusion of your dusty travels. I only wish we had something to filter and pressurize our vehicles in Iraq, the dust there was unbelievable. When vehicles drive through it it almost acts like a fluid spraying out from your wheels.

Drew

The inside of the teardrop is wall to wall mattress.

I'm liking the sound of that...mobile cat nest.
Del

If you can get hold a a video camera with "Nightshot" feature or similar, that is the Sony name I believe, you can photograph Infra Red sources, but with slight mods, you can make it work even better......

To make it work REALLY well, you need to buy a special filter that blocks all light and only allows IR through. Or use a piece of black exposed camera film to block out all normal light, but let through IR.

Mask off the IR LED spotlight (my Sony Cam has one, but the light cannot easily be seen, use another camera to check if you have this or not!). if you have one, cover it with several several layers of tape. Check afterwards that it is fully blocked from emitting IR, again with another camera.

Then blow warm air (on a cold night!) into your "sealed up" 'van and photograph the outside with the specially prepared camera or a normal IR camera..... You will easily see the hot air literally GUSHING out of all the holes that you are not finding right now..... Don't forget to check UNDER the 'van too.....

Of course if you have access to an IR Camera, use that first!!!

Check out these (and more!) websites, just search on Google with "infra red :-

http://www.thenakedscientists.com/HTML/content/kitchenscience/exp/make-an-infra-red-camera/

http://www.wikihow.com/Make-a-Webcam-Into-an-Infrared-Camera

http://home.comcast.net/~zachstern/toyir/toyir.html

http://www.darvill.clara.net/emag/emaginfra.htm

And if you want to see what a Fart looks like in real life:-

http://www.youtube.com/watch?v=aqCfVVkT2KI

What about stage smoke bombs/pellets: I think plumbers use something similar to look for leaks too.