Adventures in Leak Testing

[fstuneck]

Here are pics of our latest excursion into the world of leak testing a 93 Airstream Limited Classic. I'm using a 24" Utilitech floor fan that puts out maybe 5000 cfm. The pic shows the rear queen base flipped up and I cut a piece of 1/2 plywood out to rest on the bed frame (over the drawers, etc.)with a 20 inch hole in it.
Then had to try (read that: "really try") to seal up all the places where air could leak out. We realize that new window and door gaskets will help. Using a purchased bubble solution from Walgreens. You can use dishwasher liquid (like Joy Ultra) with a little glycerin added in to make the bubbles better.

We found a few windows leaking at the bottom (middle of bottom).
Found the small square outside lights leaking terribly which is contributing to a bad floor underneath them in the front of the trailer.
Still continuing to check. There are more leaks for sure.
The tops of things were better than expected, like the awnings and such.
Also, have a 66 Globetrotter to check out later. . perhaps with a different setup.

[memgrove2000]

Great idea!... I don't have a rear bed with access to the outside like you so I have been toying around with the idea of using my gas powered leaf blower with a plywood cover and some clamps in a accessory door opening. Trying to do the same thing....

[Jammer]

Excellent post.

I'm in the process of buying a late 1960s camper and plan to do something similar.

Did the amount of airflow seem like it was about right? What bubble solution did you use? Any problems at all with it staining or attacking the aluminum in any way?

[fstuneck]

I'm just using Super Miracle Bubbles by Imperial from the local pharmacy (80 oz.); cost $3.00. Course, you could just do a Google search for bubble solutions too:
Here was one of many: Bubble Town, soap bubble fun and magic - Bubble formula
Just a soapy sort of solution, doesn't seem to be hurting anything. I'll wash the camper after a while here anyway. I tried wiping it off and didn't notice anything special.

I wanted a lot of airflow because we have a very large camper. Couldn't find out what airflow cfm the SealTech 4300 puts out. The local dealer here (Pleasureland RV) charges $100 for the setup and $98/hr thereafter. They're probably pretty good at it. They primarily use the machine to check their own units before they are sold, etc.
I think there are soooo many places for air to leak out, that airloss is a big deal; so I wanted a lot of volume. A calm day helps out also. I can't hear the fan inside the trailer the way I have it, but sometimes I can hear air hissing out around windows.
What I want to know is: why does water come in thru those little places??? Is it like a vacuum inside the trailer or what? Cold to hot. Driving in the rain? Driving rain? Why does it come in when it could go straight down to the ground. Maybe some tech person can tell us.
Hope this helps. This is fun stuff!

[Minno]

Originally Posted by fstuneck

What I want to know is: why does water come in thru those little places??? Is it like a vacuum inside the trailer or what? Cold to hot. Driving in the rain? Driving rain? Why does it come in when it could go straight down to the ground. Maybe some tech person can tell us.

Love your setup! I'll have to try something similar in Little Girl this summer once I think I have all the leaks fixed.

To answer your question - surface tension and capillary action will draw water into places you would never think it would go. Even uphill sometimes! That's why on home roofs, you have a drip edge. And on older home window trim, they cut a saw kerf in the underside of the window sill to make a break in the flat plane of the wood. Water hits the break, and from there drips to the ground instead of being drawn up into the underside of the window. Another example is a Pyrex measuring pitcher. They have a spout for a reason - to break the surface tension. Try slowly pouring water out of an almost empty pitcher on the side sometime - you’ll understand what the spout is for, and how water get climb into the pin holes in your trailer.

Chris

[theveths]

Maybe I'm a little slow, but what purpose does the plywood serve? Can I just put a huge fan inside and close all the windows and door? Or does the air come from outside?

[JFScheck]

Nice - one hell of a great test rig!

[Becky B.]

I can't WAIT to try this out. I have leaks that I can't find & need to before proceeding with my project. Hope it works! Thanks for the idea!

[fstuneck]

I'll have to try the fan inside alone. I had assumed that just having a fan inside would only make the air swirl around and not pressurize the cabin. Gonna try it today though. I'll repost after awhile to let you know how it turned out.

ps - I was all over the top of the AS yesterday and still amazed at how tight the top seemed. I have a couple of messy fan units to replace, but the seams and rails and upper areas showed no bubbles.

[Becky B.]

Originally Posted by fstuneck

I'll have to try the fan inside alone. I had assumed that just having a fan inside would only make the air swirl around and not pressurize the cabin. Gonna try it today though. I'll repost after awhile to let you know how it turned out.

ps - I was all over the top of the AS yesterday and still amazed at how tight the top seemed. I have a couple of messy fan units to replace, but the seams and rails and upper areas showed no bubbles.

I would think it would just swirl around too if you don't have some source of air. I'm at our greenhouses right now & looked at your post again to see what size fan you used. We have a really big one, but I don't want to blow out the seams! I'm interested to know how it worked by just using the fan.

That would save some $ & work if I don't have to get a sheet of plywood.

[fstuneck]

Tried the fan inside a closed trailer and no bubbles showed up at all on KNOWN leaky areas. Sort of figured it wouldn't work. I believe you're not going to blow out any walls with the kind of pressure from fans. No evidence of that at all. Just too many other leaks probably.
I could have just cut out a hole in the bed base also and then maybe hinged it or something; that way allowing further testing every year. Gotta have that outside air coming in pressurized. I lived in a house with a 3 foot attic fan that had enough suction to pull drapes away from the walls. You could do the same with your house (i.e., energy audit stuff) to find incoming leaks, like around outlets, etc. Still have to fix the leaks in the trailer now.

[Foiled Again]

The human body gives off two quarts of moisture daily just through breathing. We breathe, shower, cook, and occasionally sweat inside our airstreams - and THAT moisture has to go somewhere. I have the bare aluminum walls inside. They are NOT sealed at the seams and they are applied with POP rivets that have teensy holes in the center. So internal moisture that is not vented out can make it's way between the walls and into the fiberglass insulation. I'm sure that even if one has the "mouse fur" interior, moisture can accumulate in the mouse fur as well as migrate through the interior aluminum seams.

SO....

It seems to me that it might not be a bad idea to have the bottom side of the windows leak air - or for air/moisture to be able to evaporate from the bottom of the centerline seam. If you think about it, wouldn't it actually make good sense to have a "drip edge" where the floor meets the walls that dripped moisture outward and downward below the exterior band that conceals the rivets?

I am once again chasing a phantom leak near my rear wraparound windows, but when I seal my window frames, should I really seal the bottom once I've gone around the radius? I'd rather have capillary action vent that water OUT than just let it proceed to the floor.

HOWEVER - by not sealing the bottom edges, is it possible that eastern Virginia's well known high humidity is seeping IN between the walls - and what happens when I run my Air conditioner on a 99 degree day with 99% humidity. I see the outside of the trailer develop sweat, is the same thing happening between the walls?

NOTE, I do always have my bathroom and shower vents open even in 20 degree weather - except when there's a noreaster blowing with 50 MPH winds. This gets rid of a lot of humidity buildup.

Paula

[Becky B.]

I got my chipboard this evening & cut the hole in it & fit it to the streetside twin. I'm gonna give it a whirl tomorrow afternoon. Hope it works!

[Steve Bryant]

This is a great idea/concept. Has anyone else tried this and what are the results?

Thanks,

Steve

[pullswitha40]

Lots to think about.......


To deal with condensation, the old Spartans have a drip channel under the windows that leads to the outer wall and then there is a space between the upper and lower skin section to make a path for the moisture from the windows can run out to the outside.

Then there are weep tubes(my name) at the bottom of the walls in the c-chanel that allow moisture to funnel through the floor and drip out under the trailer........but that is 1940s technology. I read here that someone used copper tubing with a flared end epoxied in place........brilliant idea....sorry I can not remember who to give credit to for that one.

A few decades ago the construction industry got all excited about sealing up home....super insulated and everything sealed up tight as a drum.....everyone who lived in them got sick and the home rotted away....so then they started adding more vents.

The idea here is we need to have our trailers breath, but we also need to avoid moisture getting in and control moisture getting out.

I have not read much about AS yet, but was impressed with what I saw on the Spartans.