Waterproofing

[ColemanCampingFamily]

Got a quick question here....I am installing an window AC unit tomorrow in the PUP and I was wondering if I need to waterproof the inside canvas to avoid any condensation on the inside (if that is possible). We will be camping in Ocean City, MD for a week (leave Monday) and due to the fact that it is the beach, I am sure that it will be humid. Just wondering if anyone has waterproofed the inside as well as the outside canvas. (By the way, my PUP is soft-top, if that makes a difference.)

Thanks!!
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DW - 69  :U
DH - 67  :!
DS - 00  :W

1985 Coleman Aspen - AKA "Patches"

[wavery]

Got a quick question here....I am installing an window AC unit tomorrow in the PUP and I was wondering if I need to waterproof the inside canvas to avoid any condensation on the inside (if that is possible). We will be camping in Ocean City, MD for a week (leave Monday) and due to the fact that it is the beach, I am sure that it will be humid. Just wondering if anyone has waterproofed the inside as well as the outside canvas. (By the way, my PUP is soft-top, if that makes a difference.)

Thanks!!
--------------------
DW - 69  :U
DH - 67  :!
DS - 00  :W

1985 Coleman Aspen - AKA "Patches"

If condensation is going to occur, waterproofing will not help.

Condensation forms from the difference in temperature on either side of the fabric. The water forms from the air, not from any fabric penatration. You can get condensation on glass.

[sewserious]

You need to provide some ventilation to allow the extra moisture to escape.  Even breathing while sleeping at night can cause condensation on the inside without the air.  You are in a tent remember.

Open the tops of the bunkend panels or the vinyl windows just a bit, just enough to allow a little bit of an opening, a couple of inches on each side of the middle will do it.  Gives you some air exchange without letting out all the cold air.  Also, don't try to keep it like a meat locker in there, just keep it cool not cold.

[austinado16]

It's important to remember that a real airconditioning unit removes moisture from the air as part of it's "conditioning" treatment.  So, if you set your unit on recirculate, you won't be drawing in any outside moist air, and you'll be "treating" just the air inside the PUP.  Similar to switching to recirc on your car's A/C system.

[wavery]

You need to provide some ventilation to allow the extra moisture to escape.  Even breathing while sleeping at night can cause condensation on the inside without the air.  You are in a tent remember.

Open the tops of the bunkend panels or the vinyl windows just a bit, just enough to allow a little bit of an opening, a couple of inches on each side of the middle will do it.  Gives you some air exchange without letting out all the cold air.  Also, don't try to keep it like a meat locker in there, just keep it cool not cold.

You don't want any openings while running the AC. In fact, it's best to search out any air leaks and put a towel or something in it.

Try opening a window in your car on a hot day with the AC on. You will quickly see what I mean.

Any condensation that could possibly occur from running the AC, would theoretically occur on the outside of the material (the warmer side). I doubt that you could get it cold enough inside for that to occur.

[sewserious]

You don't want any openings while running the AC. In fact, it's best to search out any air leaks and put a towel or something in it.

Try opening a window in your car on a hot day with the AC on. You will quickly see what I mean.

Any condensation that could possibly occur from running the AC, would theoretically occur on the outside of the material (the warmer side). I doubt that you could get it cold enough inside for that to occur.

Actually, I ride around with the air conditioner on and the window partially down all the time in the summer, cuz I smoke and I hate the smoke in the van, so no I don't know what you mean.  I don't have condensation problems because of that.

The cooler air inside the pup will condense (you are still putting a lot of moisture in the air, especially at night, just from breathing), as it will be MUCH warmer outside than in (at least around here where it is 82 at night a lot of times).  COOLER air condenses.

[waygard33]

Actually, it's not the cooler air that condenses...warm air condenses.

Warm air can hold more moisture. When it bumps into cooler surfaces (like a glass of ice water in the summer time), the warm air in near the cool surface cools down and can no longer hold the amount of moisture it has and deposits it on the cooler surface.

Also theoretically, the AC doesn't cool anything. It just takes the Heat that's in the PuP and puts it outside the pup. Along with it goes the moisture.

Just my 2 cents.

[mike4947]

As the others have said the AC unit also acts as a dehumidifier as well as a cooler.
Folks depend on the AC's removing mositure in humid climates.
As an example rooftop units have a reputation (and well deserved in most cases) for soaking down the outside tenting from moisture removed from the inside of the camper. Even cars with AC when left sitting with the AC on will leave a puddle usually under the pasenger side of the car that is mositure removed from the inside air.
And it's also a reason why window units need to be mounted with the majority of the unit outside the volume to be cooled.

[sewserious]

Okay, back on topic.  The OP asked about waterproofing the inside of the canvas.

To the OP, no you should not waterproof the inside, that will do nothing to stop condensation and may affect the breathability of the canvas.  The waterproofing only stops moisture from migrating from outside to inside or vice versa.  Water wicking from the inside to the outside is not a problem.