Condensation, heat, air ventilation

[Casemods]

Having trouble with water build up on the windshield and on the rubber around all 4 doors on the top of the window as well as on the front plastic dome light cover and a few other areas.

I bought some window covers that allow the windows to be cracked a bit but they only allow for about an inch and they are designed so that there is only about 1/4" between them and the window. They did seem to help a little bit though.

I bought some 12v cross flow fans that I'm thinking of mounting so they blow air out of the vehicle with the cracked window. I also have 12v computer fans. What would be the best fan orientation? I have 4 doors and sleep in the back with the rear 2 doors.

Lastly, can I use a propane heater with the windows cracked and the exhaust fan on? What's this hype about diesel heaters? I heard you need to exhaust them - can you use flexible hose for the exhaust? I could mount it much easier if that is the case.

 

[JDelete]

You, as a living person who breaths, are exhaling moisture with every breath. There is no way around that.

The key to avoiding condensation is to keep the temperature higher than the dew point of the air.

You can lower the dew point—to a certain point—by having good ventilation. This will only work to a certain point, however. If the air outside has moisture in it, such as in the early morning, in humid environments, etc., then ventilation will just be exchanging moist air with moist air.

That leaves the other choice—raising the temperature of the air and the surfaces prone to condensation.

Any type of heat that exhausts its exhaust gas will help with this. There are propane, diesel, and gas heaters that all draw their intake and exhaust gas from the outside and must be properly vented.

Propane heaters such as the Mr. Buddy will only exacerbate your problem since they put moisture into the air.

Depending on your heat requirements and the amount of solar energy and storage you have available, minor use of electric heat might work for you. This is dry heat. Keep in mind, though, electric heat will require a significant solar system and is not practical for the average setup.

 

[PlethoraOfGuns]

Breathing inside will increase moisture in the air. Adding non vented propane heat like a Mr. Buddy heater will turn your interior into a swamp with a side of carbon monoxide. You must ventilate to reduce these issues. If your vehicle isn't insulated, you're always going to deal with condensation issues.

Vented heaters like the diesel heaters you hear about will get rid of the moisture and carbon monoxide buildup. But again, you'll still likely have condensation issues on interior body metal because of the temperature difference between inside and outside. But will be less condensation because the air moisture content will be much lower.

 

[LargeMarge]

Having trouble with water build up on the windshield and on the rubber around all 4 doors on the top of the window as well as on the front plastic dome light cover and a few other areas.

I bought some window covers that allow the windows to be cracked a bit but they only allow for about an inch and they are designed so that there is only about 1/4" between them and the window. They did seem to help a little bit though.

I bought some 12v cross flow fans that I'm thinking of mounting so they blow air out of the vehicle with the cracked window. I also have 12v computer fans. What would be the best fan orientation? I have 4 doors and sleep in the back with the rear 2 doors.

Lastly, can I use a propane heater with the windows cracked and the exhaust fan on? What's this hype about diesel heaters? I heard you need to exhaust them - can you use flexible hose for the exhaust? I could mount it much easier if that is the case.

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In warm weather, we use a Craftsman 20v fan on LOW for sleeping.
A 2a battery lasts a couple-three nights, we keep a spare battery next to it.
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In cool weather, we use a Wave 3 catalytic heater... on its LOW setting of 1,700Btu.
Irregardless of weather, we always have two windows open on opposing walls.
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Do you know how many times we got on the roof chasing leaks, coating seams and taping over anything remotely looking as though it could be the source of the interior rain?
Over and over, a dozen times in our early years.
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It slowly dawned on us the 'rain' was condensation caused by the temperature differential between the inside wall and the inside air.
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2003, for our ExpeditionVehicle, we installed:
* adhesive-back acoustic insulation against the wall, then a gap, then
* one-inch pink-board, another air-gap, then
* two-inch foil-side poly.
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Our windows are 3010 (three feet wide by a foot tall) dual-pane sliders designed for a stand-still house.
Our windows are open 24/7/360°... all day, all night, year-round.
With this combination of insulation and tiny windows and ventilation, our interior 'rain' is cured.
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For a vehicle with the standard panorama windows around the operator area, or a RecreateVehicle with yuge holes in the walls, I see no reasonable method to eliminate condensation.
The glass cannot be insulated.
Perhaps a few 120vac dehumidifiers running non-stop?
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On the 'plus' side, the cockpit makes a great greenhouse.