Condensation Problem on front window.

[Fleetwood_Coupl]

I pulled the curtain back covering the front windshield this morning only to find 1/4 of water along the bottom and condensation build up about 6 inches up the window. I had just finished installing Reflectix on all the other windows and was about to install it on the front. Now I am worried it will make the condensation it even worse. Is there a product that will help stop this, or should I try to cover it from the outside?

[BigSur2]

Would be nice to get examples of which dehu's people are using.....i.e. the only kind you can find at camping world vs. just buying an electric 30 pint from Walmart. I am also in the market.

[msturtz]

Fleetwood Couple wrote:
Update, tried the next night with the overhead vent cracked...ice on the inside of the window was even worse and the heater kicked on even more. Also my weather station said the inside humidity was 25% which is lower than outside so how will a dehumidifier help? Seems most folks are using the pillows that cover the vents so how are they ventilating? Cracking a window?

Keep in mind that the humidity is based on the temperature. The lower the temperature with a fixed amount of water vapor the higher the humidity. Most people that have humidity problems are using catalytic propane heaters or cooking inside with propane. Doing this dumps massive amounts of water vapor into the coach. The issue is as soon as that water vapor hits the front windshield which is single pane it will condense out. If you have low humidity inside the coach by using a mechanical dehumidifier you can mitigate the problem by using the front fans or a small fan blowing on the front windshield which should reduce the likelihood of water collecting. A good dehumidifier can drop the humidity quite a lot. You won't eliminate the condensation on the front window the idea is to keep it from collecting on the front dash area. The reason eliminating the condensation on the front window is nearly impossible is because it is single pane and you would need to drop the humidity on the inside of the coach to less than the dew point of the temperature outside. That is very difficult to do because in the winter it is 30 - 50 F warmer inside vs. outside. This means 25% - 35% RH inside at 75F would be past the due point at 30 F. Having a fan on the front window can attempt to keep the window warmer to keep the water from staying on it. Opening a window or vent only works if you are producing a lot of water vapor such as cooking using propane or showering. In that case open the vent and then close it. The only other thing you really can do is to add a cover on the outside of the window to attempt to keep the window warmer.

[TexasH]

J-Rooster wrote:
Yes, there is a product that will stop moisture inside your coach it's called a Dehumidifier! You can buy them at most RV Shops. It's the greatest device that I have purchased for my coach. I have my dehumidifier placed between my split windshields and I empty 3 to 4 inches of water out of it a week. Great Question!

Yep! I bought one 3 years ago and haven't had a problem with condensation since. It's much cheaper at Walmart than RV shops. Just plug it in and empty the water every once in a while.

[rgatijnet1]

Unless your interior humidity is zero, there is still moisture in the air that will appear on the cold interior surfaces. This is the same reason why condensation forms on the outside of a glass of ice water.
When in your automobile and the windshield starts to fog up, what do you do? Most people turn on the defroster which blows warm air directly on the windshield, which is what you can do in your RV when you are driving.
When parked, you can do the same thing with a fan or with an electric heater aimed towards the windshield area. Unfortunately when you draw your privacy curtain, you prevent the circulation of air on the glass.
In this case the only alternative is to lower the humidity in your RV to an acceptable level. This can be done with electric resistance heaters or a dehumidifier. A dehumidifier is basically a small AC unit and removes water from the air the same as any other AC unit. Air passing over the cold coils release moisture that is collected in a tank. The dehumidifier also has the advantage of exhausting warm air which means it acts somewhat like a heater in Winter months.

[Fleetwood_Coupl]

Update, tried the next night with the overhead vent cracked...ice on the inside of the window was even worse and the heater kicked on even more. Also my weather station said the inside humidity was 25% which is lower than outside so how will a dehumidifier help? Seems most folks are using the pillows that cover the vents so how are they ventilating? Cracking a window?

[J-Rooster]

Oasisbob wrote:
We run an electric water collecting dehumidifier in the HTT during winter outings. Leaving windows cracked or vents seemed silly. Now we dial in the humidity we want. We have been known to put the unit in the shower and dry cloths by hangin them in the bathroom. I think these should be standard equipment in all RV's.We have collected three gallons of water from the air in less than 24 hours

X-2 on being standard equipment in a RV!

[weathershak]

Use towels to collect the water on the dash. The windshield works great as a dehumidifier. I covered the outside of the windshield last winter along with all the side windows. I started to get condensation on the walls. I didn't like that, so I no longer cover the outside of the windshield. I crack a vent at night. Run the fan when showering and cooking, and head for the laundry weekly to wash and fully dry the clothes.
My windshield faces the sun. I keep the privacy curtain closed and open the vent windows slightly during the day. The sun still heats up the interior well and removes the moisture from the windshield and towels.

[rgatijnet1]

Since the topic is discussing dehumidifiers, I thought I would add this link. There have been several dehumidifiers that have been recalled, including one that I had. Check the list and see if you have one that has been recalled. You will get a check for the MSRP of the unit. Mine was several years old and I got a full refund. Recall list

[Oasisbob]

We run an electric water collecting dehumidifier in the HTT during winter outings. Leaving windows cracked or vents seemed silly. Now we dial in the humidity we want. We have been known to put the unit in the shower and dry cloths by hangin them in the bathroom. I think these should be standard equipment in all RV's.We have collected three gallons of water from the air in less than 24 hours

[msturtz]

We installed a portable mechanical dehumidifier in our old TT and moved it to our Class C and now it is in our Class A DP. We set it to 35% RH and automatic mode and we have minimal humidity problems. Water is the death or RVs so it is critical to keep the humidity down.

[doxiemom11]

Google Eva Dry. They have some small units that work well. We have one that we sit on the dash between the curtains and the windshield and it does help keep the moisture down. A hint I read and was going to try. Spray windshield with water and then stick bubble wrap onto the glass. It will act as an insulation barrier. When the sun is out - remove and let sun in to warm things. Simple to reinstall - just spray glass again. I haven't tried this, but will as soon as I pick up some bubble wrap rolls. An older motorhome here has a map light that is between the curtains and windshield. They leave it on and it provides enough heat to keep the condensation off the windshield. We don't have one located to do that.

[John_Joey]

I don't know HVAC:h. We spend winters next to the Gulf and there is nothing as nice as a dehumidifier. Warms the place up some, and takes that damp feeling out of the furniture.

Seems like the old timers that grew up on Trailer Life magazine do the cracked vent idea process though. I think that came out with running a non vented propane heater and the moisture it would put out.

Don't know how a crack vent would ever pull the dampness out of the furniture though, and heat does rise so if you're trying to stay warm it seems counter productive.

[Golden_HVAC]

Hi,

Basically I just used a bath towel to dry out the windshield when it got wet. Or a smaller dish towel, that I can hang on the oven door to help dry it out.

Or you can place one of your heaters near the windshield, and it will blow warm and very dry air across the windshield, keep the window warm, and prevent the condensation from happening there.

I would not bother with a dehumidifier, they are kind of expensive, while opening a roof vent while cooking is required, just leave it open about 1/4" all the time, you will bring in some dry outside air, and constantly let out some moist inside air through the roof top vent.

Air has a 'relative humidity' so the number of 'grains' of water that air can hold varies with temperature. So outside air with 85% humidity and 43F can only hold about 15 grains per cubic foot of air, while the 70F air that is leaving with 65% RH can hold about 200 grains of moisture per cubic foot. So you are bringing in much dryer outside air.

A dehumidifier has a electric compressor that cools the incoming air to about 40F on the first coil, then heats the air going through the condenser to about 85F, so that the air drops to about 15 grains of water (leaving it on the cold coil, just like in a HVAC system) then heats it back up to 85F where it can absorb much more moisture, and is very dry now. You just skip the electric compressor part by bringing in outside 40F air and exhaust the 70F moist air.

When I lived in Portland OR in my motorhome for one winter, I used a 25' long #12 gauge extension cord to plug in one of my electric heaters. I ran the cord into the basement, and through a fitting in my bedroom that the factory installed. Then I plugged in one heater there, running it on high heat. It draws about 12.5 amps. With the 30 amp RV service, I ran two other heaters on low heat output, and that kept it toasty warm inside.

At night, I would shut off the two other heaters, and just warm the bedroom. In the morning, I could run one heater on high - normally in the bathroom, while warming up the front of the coach. I did not use a coffee maker, or toaster oven. When running the microwave, I would shut off the heaters. I never tripped my 30 amp main breaker.

Good luck!

Fred.

[John_Joey]

Fleetwood Couple wrote:
There are no weep holes. This is the front windshield it's sealed up all the way around. The water was in the bottom frame of the window. I am going to see about locating a small dehumidifier. Not much left to run anything else. We're already shuting stuff off just to make coffee. 30 amp service is all we have.

Dehumidifier is the right answer, if you're living in the rig. 30 amps should be enough. I'm guessing you might be running an electric heater or two on the same line as the coffee maker. More then likely the line is a 15 amp breaker.

Good thing about a dehumidifier is if you can find a cheap used one in a second hand shop they usually are not very energy efficient and will throw off heat keeping you warm in the process.