Moisture/Condensation Problem

[LiveFreeorCry]

We are new to our fifth wheel, and just moved our unit to a longterm site in Florida. It has not been raining, but we are getting excessive amounts of moisture on the insides of our windows and on the wall above our bedroom slide. We ran the furnace the last two nights with temperatures in the 30s, and I assume this is contributing to the problem. I opened windows today and am running fans, as well as cleaning as much of the wetness as possible. Other than ventilation and fans, any suggestions? Should I skip out on the furnace in lieu of dryer heat? Is there a problem with my seals, or is it with my ventilation? It hasn't rained at all, but it is a humid climate. We are new, just looking for suggestions. Thanks in advance.

S and H
2012 Kyestone Cougar 331

[Logan X]

Welcome to the forum. I think dryer heat would help. Also cracking a window or a vent at night would also probably help. Drying it out during the day with fans and the windows open is good. I would also open up the cabinet doors to get some airflow into the cabinets.

[JRTJH]

The human body produces about a pint of water (by breathing) every day. Showering will add at least that much and cooking will also contribute additional water into the trailer "inside space"...

How much is absorbed, vented outside and how much will remain to condense on the cooler surfaces (windows, cool cabinet interiors, behind the sofa and behind/under the mattress will depend on how much water (humidity) is inside the trailer, how much is in the air outside the trailer, the temperature of the trailer interior compared to outside, etc.

Most people in moderate humidity areas find that opening a window on one end of the trailer and opening a roof vent on the opposite end of the trailer will control condensation on windows in most conditions. ALWAYS run the bath roof vent when showering and ALWAYS run the kitchen vent hood (if it vents outside) during cooking.

Some people in high humidity areas (like Florida) find that a dehumidifier is needed to help control moisture inside their trailer, even when doing the above things. It's the "nature of the beast" in small, confined spaces.

Controlling moisture is important, not only for protecting against mold and mildew, but also to help maintain a healthier "inside space" for comfort and for medical reasons.

[Frank G]

Where are you in Florida, we have had extremely low humidity the last 3 or 4 days. The dew point does show up at night. We leave a small window open a crack 24/7, run the vent fan when showering and cooking. What is this with "Dryer Heat" are you dumping the exhaust from a clothes dryer into the unit? Not good. We are in our 4 season in Florida (now residents) and never an issue with moisture, mold or condensation. When we leave for the summer we leave a A/C unit on, set at 80. Costs about $25.00/month.

[Logan X]

Maybe it’s drier heat not dryer heat? Anyways, I think they mean electric heat from a space heater instead of propane fueled heat from the furnace.

[dadnjesse]

Where are you in Florida that it's been in the 30's

[flybouy]

Good venting practices are essential for holding down the interior moisture content in a small space when it's cold outside. The warm moist inside air will condensate on the cold surfaces such as the windows.

Keeping a vent partially open, bathroom fan on when showering, removing wet towels after the shower, etc.

[LiveFreeorCry]

Thank you for the suggestions. We are going to keep trying to vent, and I put a small dehumidifier in the bedroom. I did mean drier, rather than dryer, heat. We don't have a bathroom fan, but I especially appreciated the tip to make sure to always utilize the oven fan. I passed that along to my fiance. We are in north central Florida, which has seen lows in the 30's the last three nights. The temperature is back up for now, so it should be less of a problem for a few days.

[LiveFreeorCry]

Originally Posted by JRTJH

The human body produces about a pint of water (by breathing) every day. Showering will add at least that much and cooking will also contribute additional water into the trailer "inside space"...

How much is absorbed, vented outside and how much will remain to condense on the cooler surfaces (windows, cool cabinet interiors, behind the sofa and behind/under the mattress will depend on how much water (humidity) is inside the trailer, how much is in the air outside the trailer, the temperature of the trailer interior compared to outside, etc.

Most people in moderate humidity areas find that opening a window on one end of the trailer and opening a roof vent on the opposite end of the trailer will control condensation on windows in most conditions. ALWAYS run the bath roof vent when showering and ALWAYS run the kitchen vent hood (if it vents outside) during cooking.

Some people in high humidity areas (like Florida) find that a dehumidifier is needed to help control moisture inside their trailer, even when doing the above things. It's the "nature of the beast" in small, confined spaces.

Controlling moisture is important, not only for protecting against mold and mildew, but also to help maintain a healthier "inside space" for comfort and for medical reasons.

Great info, thanks!

[rhagfo]

Originally Posted by LiveFreeorCry

Thank you for the suggestions. We are going to keep trying to vent, and I put a small dehumidifier in the bedroom. I did mean drier, rather than dryer, heat. We don't have a bathroom fan, but I especially appreciated the tip to make sure to always utilize the oven fan. I passed that along to my fiance. We are in north central Florida, which has seen lows in the 30's the last three nights. The temperature is back up for now, so it should be less of a problem for a few days.

Well #1 is that the gas furnace DOESN'T add moisture to the inside of your trailer! The combustion chamber is sealed and any moisture produced by the combustion is vented outside. If it isn't you would soon be dead from Carbon Monoxide poisoning.

If your bathroom doesn't have a vent fan, add one, or at least open a roof vent while showering.

Get a decent sized dehumidifier, and use it, we full time current on the Oregon Coast. Outside humidity 93% inside 47%.

[foldbak]

I have a friend that lives in his RV in Florida and swears by this
https://www.lowes.com/pd/Keystone-Ke...E&gclsrc=aw.ds

[sourdough]

Where in N central FL are you? We are about 20mi. S of Tallahassee right near the water and we have some very high humidity levels (98%+). We keep the LR and bathroom vents cracked, run the bathroom fan when showering, try to watch when leave windows and doors open to "catch a breeze" if the humidity is really high etc. One thing we found our first year here was that to actually control the humidity decently we needed a dehumidifier. Went to Lowes in Tally and bought a 35? pint HiSense unit years ago. Extremely satisfied and no issues even with the door open. We don't run it when the humidity levels are normal and we've never had any condensation anywhere....even in the 30s.

[Logan X]

Originally Posted by rhagfo

Well #1 is that the gas furnace DOESN'T add moisture to the inside of your trailer! The combustion chamber is sealed and any moisture produced by the combustion is vented outside. If it isn't you would soon be dead from Carbon Monoxide poisoning.
.

That makes sense, although the CAPITALIZATION and punctuation! may be construed as unnecessary.

[rhagfo]

Originally Posted by Logan X

That makes sense, although the CAPITALIZATION and punctuation! may be construed as unnecessary.

Well I see so many times people post don’t run the furnace it puts moisture in the air, it just doesn’t happen.
Older catalytic wall heaters would as the combustion is using air inside the trailer. Newer gas furnaces that vent outside add zero moisture to inside air. I don’t like heating outside air so keep the vents closed except when showering. We therefore run a dehumidifier.

[travelin texans]

Originally Posted by rhagfo

Well #1 is that the gas furnace DOESN'T add moisture to the inside of your trailer! The combustion chamber is sealed and any moisture produced by the combustion is vented outside. If it isn't you would soon be dead from Carbon Monoxide poisoning.

If your bathroom doesn't have a vent fan, add one, or at least open a roof vent while showering.

Get a decent sized dehumidifier, and use it, we full time current on the Oregon Coast. Outside humidity 93% inside 47%.

I agree the furnace itself doesn't put moisture in the RV, but the furnace running heating the cold, uninsulated ducts in high humidity climates does add moisture inside a rv, just as warm ground temps meet cool damp air temps create fog. Add that to the moisture from your breath in cool humid climates & viola condensation.

[SummitPond]

Originally Posted by sourdough

Where in N central FL are you? We are about 20mi. S of Tallahassee right near the water and we have some very high humidity levels (98%+). <clip>

Danny

No wonder it's so humid by you - all that hot, moist air coming out of the state capital!

My guess is if the OP is in Fort White area, he's not all that far from you.

Speaking of Fort White, if you've never been tubing down the Ichetucknee River, it's something you might consider. (Ichetucknee Springs State Park- Southern Entrance, 12087 Southwest, US-27, Fort White, FL). It's supposed to hit 80 today in NE FL but I suspect the water temps are still quite chilly (they are so even in the summer).

[rhagfo]

Originally Posted by travelin texans

I agree the furnace itself doesn't put moisture in the RV, but the furnace running heating the cold, uninsulated ducts in high humidity climates does add moisture inside a rv, just as warm ground temps meet cool damp air temps create fog. Add that to the moisture from your breath in cool humid climates & viola condensation.

Where do you come up with this stuff?
My floor ducts are tight to the bottom of the floor, and never damp.
We have Cheap Heat system and use it on electric most of the time.

[sourdough]

Originally Posted by SummitPond

Danny

No wonder it's so humid by you - all that hot, moist air coming out of the state capital!

My guess is if the OP is in Fort White area, he's not all that far from you.

Speaking of Fort White, if you've never been tubing down the Ichetucknee River, it's something you might consider. (Ichetucknee Springs State Park- Southern Entrance, 12087 Southwest, US-27, Fort White, FL). It's supposed to hit 80 today in NE FL but I suspect the water temps are still quite chilly (they are so even in the summer).

Ha ha! You are right! My daughter works for the state and I'm constantly getting what is more or less insider feedback. I think you may have come upon the answer to all that hot air we keep getting here coming from the north.

[JRTJH]

Originally Posted by rhagfo

Where do you come up with this stuff?
My floor ducts are tight to the bottom of the floor, and never damp.
We have Cheap Heat system and use it on electric most of the time.

The ability of air to hold moisture is dependent on temperature. As the air warms, it expands and that "extra space" allows it to hold suspended water vapor. When hot furnace air flows through your uninsulated floor ducts (in the underbelly), it warms the air in the "unconditioned space" as that air warms, it absorbs moisture from small air leaks, open holes, or other sources. Once the furnace cycles off, the air in the "unconditioned basement spaces" cools and can no longer hold that excess moisture in suspension. It condenses on cooler parts of the underbelly and leads to rot, water damage, mold and mildew. That's one reason why manufacturers have stopped using spun fiberglass insulation in the underbelly and have gone to "Styrofoam laminated floors and aluminized bubble wrap.

Any time there is a cyclic temperature change inside a confined space, if the outside atmosphere is moist (high humidity), the "heating part of the cycle" will absorb outside moisture and the "cooling part of the cycle" will deposit moisture (condensation) on the coolest spaces in the underbelly. The condensation is too heavy to "migrate through the open holes in the underbelly and escape, so it settles on the cold surfaces and pools in low spots.

That "cyclic condensation" also occurs inside the RV as temperature rises and falls during the thermostat swings from on to off to on again. Water from showers, cooking and breathing add to the problem by increasing the inside humidity. Controlling the amount of water inside the RV (confined space) is important to preventing condensation on cooler surfaces like outside walls, inside cabinets and especially single pane windows. But don't be lulled into believing that in high humidity areas, uninsulated heat ducts in the underbelly don't contribute to moisture problems under your RV. The problem isn't just inside.

[77cruiser]

Anybody ever try a intake from outside for the furnace cold air return?