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Dehumidifier or no?

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We are in the Austin, TX area and will be for the winter and spring unless things radically change with COVID. Today is a grey, gloomy day and it has been raining pretty much all day. With cooking, dish and laundry washing, breathing, etc. the windows are starting to get moisture on the inside, especially as the outside temperature drops towards evening. We do have the little canisters that are supposed to absorb moisture, and they do, but it is fairly humid here so we are replacing them fairly frequently. 

I am thinking about getting a dehumidifier. I have found a couple that are recommended for RVs and get good reviews but I am wondering if others use a dehumidifier and what size or brands do they have and recommend among the members here.


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I have had one for a little over a year now and am pleased with it. At first I hooked it up to constantly drain and it looked like it put a lot of water on the grass. I have moved it to a different location  and  for the last two weeks, I  have not had to empty it all that often and so far have not allowed it to fill to the point where it shuts off because of a full water tank. 

It was not the least expensive one I could find, but I did purchase it  from a small hardware store in North Central Oklahoma. I have used it in the OKC area for a full winter and SE Missouri for a spring summer and a touch of fall. I am in Lawton, OK right now. 

The reason for the recent move  is it's more quiet at my current spot and I would hear it cycling off and on in it's initial spot. It worked great  for the drain and I might move it  back  if during the summer it takes  more moisture out  where I have  to empty it daily, but I doubt it will. It's not that big. 

I have been pretty much moisture free on the windows since getting it moved.  I had a wet, cold first 3 days in Lawton  and had been on the road for two  days prior. Did have condensation those first few days. I used to keep the blinds pulled and didn't really notice the condensation. I have  found out that's a mistake. No major damage, but  I  can see where water had run off the glass, down the wall and  onto the floor. I now wipe the  glass if it's wet at least in the early morning. 

Most people are using Humidifiers this time of the year. 


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Most of the problem usually comes from our activities of showering, cooking, and even breathing with the relatively small volume of air inside our RVs. I would first try making sure to open a vent in the bathroom when you shower and using the exhaust hood when cooking. A dehumidifier would probably help but we found that even when using one we needed to do things to mitigate the amount of moisture that we contribute when weather is such that we keep the windows all closed.

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We're about a hundred miles SE of you for the winter . 

We've had a dehumidifier in the past and it was just OK . 

Now we simply turn the AC on , which does a great job .

Sometimes we run a small electric ceramic heater along with the AC to hasten the cause and to help keep a moderate temperature . 

Edited by Pat & Pete
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I haven't used one in the RV because our ducted A/C is also a heat pump with a "dry" function.  I have, however, used one in a SB.  We had a damp basement and ran a dehumidifier.  It worked very well in a space that is similar to a very large RV but much damper.  If you can find one that drains instead of needing emptying, you may be able to run a drain hose past a slide seal and save checking and emptying on a frequent basis.  As I recall the unit we had would take up a lot of space; it was about 2' H x 1.5' W x 1'D.  Sorry but I don't remember the brand.

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The first winter we spent in our Foretravel we made sure that all vents and the skylight were well covered. Then we noticed the moisture inside. A friendly Foretraveler told us to get rid of all that stuff and leave the bathroom vent open at least a little bit all the time. We've been doing that and no more excess moisture. Sometimes we will close the bathroom vent while showering, but always open it up and turn the fan on afterward.

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8 hours ago, sandsys said:

That tends to help in my experience. Also, moving bedding/drapes/whatever away from walls during the daytime helps.


Thanks Linda, 

I forgot in  my first trailer finding moisture on the walls  near the bed from pillows just thrown  against  the  wall. Condensation forms where  areas are  allowed  to cool in  an otherwise warm environment. The moisture  from  the warm is drawn to the colder area. Is the term "Heat  follows cold" correct? 


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Many many years ago i took a class in Hydrology/Meteorology and had to do LOTS of calculations on how water changes phases under all kinds of different conditions. Short answer is what youve already read here: moisture forms on surfaces when the warm air comes into contact with a surface cold enough that the air no longer can hold the vapor. So it condenses/changes state from vapor to liquid- usually onto windows and walls in a RV. Some things you can do:

- keep it hotter inside

- keep the air moving along cold surfaces (via fans or keeping the bath vents open a bit to create a natural flow)

-run a dehumidifier  (non reusable puck types dont really do much ime)

I do all 3, just depending on specific conditions that day. If i'm paying for the propane but not the electricity then its Hello Mr Ceramic Heaters!  If i am paying for both, then its whatever is convenient (they are both about the same cost for me).  I also run small fans during the night at the more susceptible areas, eg where normal air flow is restricted (behind a couch, etc).  I also have a EVAdry sized to my RV and i do think it makes quite a difference. I run the drip hose but if you do that, be sure to keep an eye on your waste tanks' levels.  I should add that its very rare for me to be camping when temps are <20F.


((btw, if you get an EVADry, get the hose from them too- its a size thats hard to find at your local or big box hardware store))


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We had this issue with our 5th wheel in the winter in the southern states.  We began cracking the windows slightly as well as the ceiling vents and the closet sliding doors so our clothes didn't get musty.  Opened the kitchen window fully when cooking and the bath vent fully when showering.  We also pulled our mattress away from the wall a few inches during the day to let it dry out.

We once traveled from Texas into Arizona and went to the store asking for a dehumidifier.  We got laughed at.  "We use humidifiers here; not dehumidifiers".   😊

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Thanks all for the responses!

We do open the vent in the bath when showering. We do not have a kitchen fan that exhausts to the outside but depending on what we are cooking and weather we will turn on the MaxFan. We open our windows as much and as often as we can as we do like the fresh air. The downside to that I have noticed is that it is usually less humid inside than out and then the outside air raises the humidity inside again. Around and around we go. 

I went ahead and ordered a small dehumidifier that should be sized right for the RV. It is not a physically large unit, gets very good reviews and doesn't cost very much. We shall see how it goes. It should be here tomorrow.

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1 hour ago, Chalkie said:

We shall see how it goes.

You are battling a problem that has been with us in our RVs for years and it seems to be worse for the more airtight RVs which are more energy efficient. The problem is that our activities of living tend to increase the humidity levels and condensation begins when the warm air inside comes into contact with surfaces that aren't well enough insulated from the cold outside. It is one of the reasons for most of us recommending dual pane windows in fulltime RVs along with better insulation. I'll be very interested to hear more of your successes and also a review of the new dehumidifier, along with a make and model involved. In my experience, there are many things which help, but none that are a total solution. 

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