Stamp Out Damp!
For those who RV in the humidity of the great Northwest using the rig in fall, winter, or springtime can be a joy for the sight seeing, but it's a great pain for the dampness. The high humidity of the region is legendary, and foggy windows can cut your views. Ah, if only that was the limit to it. A buildup of humidity in your rig can mold your breakfast cereal, mildew your clothes, and make climbing between the sheets feel like a crawl into a frigid Finish sauna.
From Where Does the Rain Fall?
From what is the source of this foul steam? Sad to say, we have met the enemy and he is us. According to one RV industry group, four folks in an RV can pump an unholy three gallons of water per day into the closed rig environment. Count breathing, sweating, cooking, bathing, and washing. Doesn't sound like much? Imagine giving the kids buckets of water and telling them to splash them around in the old motorhome. If it doesn't go out somehow, it stays in, insidiously impregnating the carpet, walls, bedding, and any other moisture-attracting surface.
Why, oh why is this the case? Modern RVs are built tight--keep out the wind, keep in the heat. As a result, moisture has little escape. Add the outside humidity that drifts in when the door flies open and closed, and you have a recipe fit for growing mushrooms. Hey! Don't laugh--if it gets wet enough, you could grow some interesting fungi, Winnebago Delecti.
So how do you cope with this unwelcome situation?
Ounce of Prevention Worth a Quart of Cure
Prevention is the first step--no, we're not suggesting you stop breathing. Cut excess moisture production. When you boil up the chicken soup, turn on the range hood. You'd be surprised at how many folks fail to take this simple step, for the chicken soup, the coffee, or what-have-you. Perhaps a major reason is because the rotten things are so loud. Consider replacing your noisy three-blade range hood fan with a four-blader, which is said to be quieter. One RVer recommends dispensing with the range hood fan altogether, and replacing it with a quieter "muffin fan."
Some recommend using the microwave oven for heating liquids. While the microwave is great for quickly reheating foods, there is a limit: It takes nearly the same amount of time to boil water in the microwave as it does on the range. The problem is the microwave will pump the moisture back into your rig--and not out the range hood. There is one small advantage of the 'wave over the range--burning LP gas produces its own moisture. Maybe you'll come out slightly ahead with the mikey, but hey, you're still blowing the moisture back into the kitchen.
While we're on the subject of LP (or butane for you easterners), yes, burning gas does produce moisture. While we'd principally think of that when considering use of the range or the oven, catalytic heaters can produce godzoons of moisture. If you're hooked up to shore power, you may benefit from running the furnace as opposed to the cat heater. Modern RV furnaces vent their combustion gases to the outside air, hence you'll have less moisture using it.
Showering also introduces plenty of good old H2O, and not just to our squeeky-clean bodies. Think of the last time you stepped out of the shower in the middle of December and tried to do your hair in front of the mirror. When you take a shower, close the doors to the bathroom and use the roof vent to release the steam. Freezing outside? Just figure you've joined the Polar Bear Club as you towel off.
Other tricks will help you fight the vapor battle. Crack the roof vents slightly. It may sound counterproductive, but the heat you lose may actually help you feel warmer, as you'll have dry heat instead of that sticky dampness. Running a fan to circulate air throughout your rig will also help chase away the condensation, and it will also even the heat levels throughout the rig, helping you feel warmer with less heat on.
Sweating windows are a perennial problem producer. Some folks actually install home-brew 'storm windows,' and that can help. The trick is to make sure they're really tight, not allowing any movement of air between the panes. Some newer rigs have the option of storms, or dual glazed glass units. Heavy drapes can help in some instances, but then you block out the view. You pays your money, you takes your choice. We tried a silicon cloth to wipe down our windows--with some limited effect.
Dehumidifiers? They fall into three types: Chemical varieties use various "crystals" that either absorb the humidity and can be "recharged" by heating them up in the oven. Ever wonder what happens to the moisture you "dry" out of the package? Uh, huh, right back into your rig. Another crystal type melts down and drips into a collection container. Keep and eye on them, lest they overflow. Experience teaches it can take a lot of those little dehumidifier "pots" to make much of a dent. Another type of chemical dehumidifier simply absorbs moisture, and then is tossed out when soaking. The problem here is how many you need--one manufacturer recommends about a dozen of these little characters for a 25' rig.
Enter the mechanical monsters. From simple, electric heating elements that evaporate the water and drip it off into a sink or container, to motor and compressor jobs that draw large amounts of power and require frequent pan-emptying. A third type of mechanical dehumidifier uses a "humidistat," (a humidistat is to humidity as a thermostat is to temperature) which flips a fan off and on. The beast is placed on the floor where the heavier, damper air collects. When an objectionable degree of humidity is detected the fan turns on, pumping the damp air out of the rig via a duct. If you're handy with tools it might be worth the effort.
What's the best solution? I'll tell you mine: Pack up the rig and head to the desert when the rain starts to fall. If you can't do that, try a few of our suggestions and see if you can stay warm and dry.