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Old 12-31-2015, 11:45 AM   #1
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195RB and a constant battle against humidity.

We're having a terrible time with humidity in our 2014 195RB. It's only 19 months old and reeks of mold and mildew.

Much of the problem seems to stem from manner in which the air conditioner is installed. The 195RB uses a traditional window mount residential air conditioner instead of a roof mounted RV unit. Window mount units draw air from vents on the sides of the air conditioner cabinet and exhausts that air over the condensing coil and to the outside. But because this unit is mounted flush with the outside of the trailer (i.e. it's mounted INSIDE the camper), the intake vents (ordinarily outside the window) are inside the trailer and are drawing air from inside the camper and exhausting it outside, thereby creating a vacuum in the camper. So for every cubic foot of air that has been cooled and dehumidified, you've drawn in another cubic foot of hot humid air into the camper. In Florida, you'll never get the humidity under control like that!

My thoughts are to seal up the cabinet in which the air conditioner is mounted, and then install a duct from the sealed cabinet to the outside. This will allow the air conditioner to draw air from OUTSIDE and exhaust it back to the outside.

What are your thoughts on this solution?

Kind regards,
Lee J.

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Old 12-31-2015, 06:50 PM   #2
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We have the same unit. It IS vented to the outside - there is a vent on the roof just above it. That vent supplies the air to the sides of the AC. It's not really "in" the camper - it's inside the cabinet.

Our previous camper always had condensation problems. We are amazed how dry this unit is. Of course, we are in NY, but actually in the Summer our humidity gets quite high.

If you want to seal around the perimeter of the face of the AC, I don't see why that wouldn't work. Then ALL of the air would have to come from outside.

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Old 12-31-2015, 07:11 PM   #3
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We have the 195RB and haven't noticed this being a problem. The only time we've had condensation issues is when we've had all the windows and vents closed and are not running the A/C unit. I installed a Maxx-Air cover on the roof vent over the dinette/kitchen area - we leave that vent open at all times except when using the A/C unit. If it's cooler and we think we may need some heat I will close that vent most of the way, but not completely.
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Old 01-01-2016, 12:11 PM   #4
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We have Maxx-Air covers as well. When I have a vent open its open all the way. I leave the kitchen vent open all the time. The only time the bathroom vent is closed is in the Winter when the furnace is on.
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Old 01-02-2016, 05:41 AM   #5
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First things first...

WELCOME TO JOF!!! The members here are GREAT!!! There is a lot of GREAT information to be found here. I am sure that you will have information and pictures to share with us... so please do!!

The humidity down here in Florida is a given.. I am in Dunedin, next city north of Clearwater, and about 200 yards off the gulf. HUMIDITY...HUMIDITY.. HUMIDITY.. When we first got the TT, I originally closed it up, when we were not using it (parked next to the house), and had the same issue. I put the Maxx-Air roof vent cover over the bathroom electric fan and the front bedroom ceiling air vent. I have the ceiling fan thermostat set to come on at about 80 and the fan speed is on low. It keeps just enough fresh air circulating during the day, when the sun is beating down on everything and the humidity is peaking out. There has been no musty odor issues since. The vents are open 24/7.

I would recommend installing an electric ceiling fan that is thermostatically controlled and another vent just for fresh air (well as fresh as the Florida air can be). You need 2 vents, as the TT is pretty well sealed. If I do not have the 2nd vent open, you can hear the fan slow down as there is not enough air coming into the TT from the outside. Ideally, one at each end of the TT would be best for circulation. Also a small table top fan on the floor blowing air toward the ceiling will help circulate the air.

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Old 01-02-2016, 06:35 AM   #6
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Your problem and your logical solution is not what you think it is. This is not a failure of design - it is an operator failure.

All quoted From: RV Dehumidifier: Do You Really Need It?

An RV is prone to humidity as it is exposed to an outdoor environment for longer time periods. The most common factors that affect the humidity inside an RV include temperature changes, washing, and cooking. These things contribute a great deal in the damage of body of an RV, as damp air in the environment settles on its walls and causes serious damage, which ultimately extends to the entire structure.


As an RV is a valuable investment, it demands our daily attention and care. To maintain the moisture level of an RV so that the exterior and interior of your RV remains safe and stable, you need to install a dehumidifier. This is a device that regulates the moisture levels in the environment to keep the chances of mold or mildew, which can settle on wall of an RV and deteriorate its structure, at bay.

You can read the rest of the article yourself, including the use of an hygrometer to monitor humidity levels.

Following taken from my RVIA Air Conditioner training book, plus my edits:

Recreational vehicle air conditioning equipment removes heat from the air inside the vehicle, where heat is not needed. (Doesn't put cold air into the vehicle)

Air flow actually is within the vehicle. Air from inside the vehicle enters the evaporator coil (which has the cold refrigerant that absorbs the heat) and then having had its heat removed the air leaves the evaporator coil going back into the vehicle. The difference between in/out air temperatures is how we measure the efficiency of the air conditioner.

The evaporator gained heat is then taken outside to the condenser coil (via the refrigerant) where the refrigerant now gives off the heat that was absorbed in the evaporator to the outside air.

The process can be reversed during the winter to heat the inside of the vehicle or building, if so designed.

Note: and there is also a lot of Not Great information provided in all of the RV forums, not just this one, from mislead good intentions, assumptions, and lack of technical knowledge, that one must sort out.
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Old 01-02-2016, 08:07 AM   #7
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Year ago I purchased a Frigidaire brand residential humidifier. It is designed to remove humidity from 1 or 2 small rooms. It runs anytime we are at home and not using the rig. We check the reservoir every couple of days and dump it outside. It shuts off if it fill up the 1.5 gallon container.
It is the only way to go if you want to remove humidity. Inexpensive and long lasting.
We are going to Florida again this Feb. and we may take it with us.
No more stale smells, no more munge on the walls and surfaces.
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Old 01-02-2016, 05:08 PM   #8
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Anytime the outside air is near 100% humidity and you cool that air, the moisture immediately condenses on whatever it can. The dehumidifier is the only remedy. I have a 2015 195RB that has the air conditioner on the roof. Really, it doesn't matter that much where it is located. Fortunately, the air in Colorado is much drier than 100%. We never had issues with condensation and mildew.
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Old 01-02-2016, 07:11 PM   #9
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I thought an air conditioner was a dehumidifier. I know when it's 80% humidity outside and only 25% inside it sure seems to be acting like a dehumidifier and what causes that constant stream of water down the side of my trailer? I thought it was the humidity the air conditioner was removing from the inside air.
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Old 01-03-2016, 08:22 AM   #10
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Originally Posted by Hohenwald48 View Post
I thought an air conditioner was a dehumidifier. I know when it's 80% humidity outside and only 25% inside it sure seems to be acting like a dehumidifier and what causes that constant stream of water down the side of my trailer? I thought it was the humidity the air conditioner was removing from the inside air.
You are correct sir. You do not need to buy a dehumidifier if you can run the AC. It may be too cold for that, but it will remove the moisture from the air far more effectively than a dehumidifier in a very humid climate.

All that water dripping from the unit is moisture removed from the air inside the RV.

P.S. Propane is the real enemy. It releases moisture when used for cooking of heating. One must vent the RV while using it.

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