Try a place with climate controlled storage. 
southwestjudy

George,

I assume that you have electric power available since you mention a dehumidifier and running your ac fans. In my professional opinion and this is part of what I do for a living. I would close everything up and would set one ac unit at 65 to 70 degrees and let it operate. You may save a few dollars in electric cost by using a dehumidifier but that would be offset by buying one. Once the temperature falls below 60 degrees you shouldn't be concerned about humidity. All that you’re trying to do is to keep mold spores from growing which causes mildew and that musky spell that is all too common inside of RV's. If you do not have electric power available then you can buy DampRid. I have used it before when I had some personal items in storage. The only drawback is you have to replace it monthly or sooner since it turns into water as it soaks up moisture. This shouldn't be a problem if you are having someone drive it monthly for you. By far the best option is operating one of your ac units continuously. I use desiccant and dehumidifiers to keep moisture out of expensive equipment made from exotic metals which has always worked well in preventing corrosion.

The bottom line is there is no reason to buy a dehumidifier since it’s just a little ac unit.

Yeah Fox I was going to say the same thing that Rollie did...he is always taking my thunder!
NOT....LOL Who ever said this forum doesn't have all the answers.

Speedywakapedia

If guesses are not allowed, I guess we'll need to conduct extensive controlled scientific experiments - and then make an engineering assumption or two. BUT, the full answer is not that black and white.

The key objective is to lower humidity to stop mold/mildew growth as sailor said.

Running the AC is a great way, but doing so is conditional. The condensate will follow the exact same path off the roof for several months keeping that same path moist. If that path crosses a seam, joint, caulk area, splashes over a window, any little microscopic hole in the roof/wall it could infiltrate into the walls and well, you know, I guess it will cause rot. We have all seen this happen. So, set it all up and run the one AC and follow that condensate path. It might flow harmlessly into a gutter and then into a downspout or it might flow over a window/joint/seam/hole. CHECK IT - don't guess the flow. Control the flow by making dikes with some window putty if need be. Get that flow away from joints/windows. But, since the rig will be moved every month, looks like you'll have no idea what joints the condensate is flowing over each time it is moved. Maybe the AC is not the best solution for you.

Of course having the windows open, roof vent fans running DEFEATS the purpose of the AC (or dehumidifier) entirely. Close the windows and kill the fans, but leave ONE roof vent open - no fan - for some natural slow convection. Setting at 65 is too cold and could even cause surface condensation as it is too cold in a warm moist area. Surface condensation could be an even bigger disaster. We are lowering humidity, not creating a meat locker. Set it at 75-80 and save some coin too.

In your case, I am a fan of the dehumidifier. WHY? You can CONTROL where the condensate goes. Place the dehumidifier over the sink (for backup) and run the condensate hose from the dehumidifier out a window (since the AC will be dumping on the garage floor anyway) and this way the water CAN NOT run over any joints. We are not talking a lot of water in either case, but either approach will maintain a damp spot on the floor. I would kill the entire rig (for safety and eliminate worry about is everything working peace-of-mind) and run the dehumidifier off an extension cord from outside the rig. Knowing that no water is flowing over your rig will ensure it doesn't flow inside a wall/joint. Knowing you rig is shut down means no worries over what is working and what isn't or is everything set up right after each drive. Driving it once a month will ensure the batteries are fine to start it.

In winter do you really need to heat it in mid TX? Will the INSIDE of a building really get sub 32 for SEVERAL days? Check the climate. I am NOT a fan of leaving an UNATTENDED RV heater running for months on end INSIDE of a building. That is just a bad idea. Done all the time, but bad. Besides, WHY heat it if it won't freeze? If you must, why 55? why not 40? My preference is to turn the stuff OFF - shut the whole rig down for storage. Stuff happens. Why worry if it is all working or not. You are storing it - so store it. If you are concerned about freezing, winterize the rig - you'll need to flush the water anyway after 7 months - and be done with it. Still, leave one roof vent open (a little) but no fan for natural circulation. Again, this is the simple and sure approach and I like simple and sure. Makes it easier for the guy driving it monthly. Just drive it and forget it. No setting things back up and worrying about did they do it right.

So there is my experienced guess. Just my opinion. Yep, I am a mid Atlantic boy so I have had my share of moisture experience in both stored RVs and stored sticks-n-bricks. JMHO.


-- Edited by RVDude at 09:01, 2008-08-23

We live here in Central Florida and have been to the Florida Keys many times so I understand how HOT it gets down there!

I can only share what has worked for us here in Lake County Florida.  We leave the covered vent hatch open a bit, and I use damp rid containers placed in the sinks and change them periodically.

I am amazed at how comfortable our 5er has remained during these crazy Florida summer days.  Of course the dual pane windows help temendously!  I see a huge difference in the heat index in our Big Horn construction over the MXT trailer we had a year ago.

Also another tip that helps here in Florida is placing cedar blocks in the trailer, keeps the moths and other critters at bay!

Good luck.
Susan

We only leave our bathroom vent open about 3 inches to allow heat to escape.

I put baking soda in containers in the refrig and freezer as well.

Damp rid works great, our rig is 38' and I put one container in the bathroom sink, one in the kitchen sink.

I empty them per the container instructions, I am at work, so I do not remember if it is 30-45-60 days and you can purchase refills.

It has worked for us, we still experience some swelling of wood doors but that disappears when the summer heat does as well.

At least we don't have the winterizing issue!

Good luck, it is brutal down there in the Keys in the summer.  I used to have a home at mile marker 99 in Key Largo at the Harborage and I was ALWAYS repairing something from corrosive salt air!

Susan