Get rid of condensation!

Jmolan

Member
I have wanted to do a write up for a while on the dreaded condensation we have all seen inside our vans. ( I am flat on my back recovering from pneumonia, so I have some time on my hands)

I will hit the basics of keeping dry, and have some stories to back it up. I apologize ahead to anyone who knows all this already. And don't hesitate to add or correct please.

OK basic concept. If you can keep this in your noggin, it will guide you as you beat the dripping.

Warm air: Think of warm air as a sponge, it can absorb a lot of water. You see warm moist air come in off the sea, climb the mountains where it is cooled, and it condenses into cloud or rain. Think of cold air as squeezing the sponge. Cold air releases moister.

In our vans, we warm them up inside by any number of methods. We also cook, have wet clothes, breath (You release a liter of water a night out your lungs) The warm inside air absorbs moister, but as soon as it comes in contact with cold metal window surrounds, pillars, uncovered windows, in condenses into water again. Think of a cold glass of lemonade or beer on a hot day, the out side is soaked. Same thing in the van.

We have all woke up in a tent with it raining on us from overhead, our vapor condensing on the colder tent surface. So how to beat this menace?

Most say "ventilate" and for many that is all that is needed. You have to give the warm water laden air a place to escape, so it does not settle on your colder surfaces.

What I learned, and found to be killer is, rather than use the air your are living in to heat up and try to vent vent (no positive pressure), set up a dynamic circulation system. If I bring cold dense dry outside air into my heater, and heat it up, I am adding a powerful force to soak up moister in the van. My heater is putting out dry warm air, that is like supercharged to absorb our vapors. Rather than warming wet air from inside the van. It is also a positive pressure inside the van. By simply cracking a vented window or just cracking the lid on my fantastic fan, the air flow scoops up the vapor and exits!

OK story time..... My boat in Bering Sea Alaska had a room about the size of a 40' container. It was bare painted steel, no insulation on the inside. It was used for gear storage, crew rain gear hooks, and a hang out spot for the crew to wait to hear what I had in mind next. Between waves slopping in to this room, the guys always came in to this room soaked and stripped off their gear and hung up there gloves etc. It had a big 220 volt industrial heater. Big fan, gong 24/7. But in the cold temps we had, the room was always wet.
It had a bare plywood floor that NEVER dyed out. The ceiling dripped like a rain forest. Everything was clammy, they called it the mushroom factory, warm as hell, but wet.
I finally had enough, I could never get them to leave the door open. I cut a 4" hole in the front of the room and plumbed a PVC pipe to the back of the big heater. I wrapped aluminum foil around the back to the heater to make sure only the air from the out side was going through the fan. I cut another 4" hole in the far end of the room near the cieling, made a gooseneck to keep out waves. My crew were very skeptical, like "oh boy there goes the Capt. again" I told them to keep the door shut. In 24 hours the plywood floor was bone dry! No more rain forest, gone. Now their gloves dryed out, and rain gear. They were pretty stoked.

So......Bring outside cold dry air into your heater, vent the warm moist air out, you will be styling.

These window vents are really valuable, and like $60. Not only to vent moister, but on a hot day I crack the window enough you cannot see it from the outside, I run the fantastic fan on suck, it moves a lot of air, keeping things cool. Hours of sitting and the van is livable when I return.

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Also the window coverings my wife sewed up have been awesome in all seasons. Foil bubble
outside, ironing board material inside, suction cups to hold. Here is link if you want to try to sew your own. They are difficult to get right for my experienced seemstress wife, but so nice!

http://roadtreklife.blogspot.com/2013/03/diy-reflectix-window-insulation.html

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Midwestdrifter

Engineer In Residence
An often used approach in Europe is too put a diverter on the intake of an espar/webasto heater. One setting is recirculation the other is fresh air. This is ideal for supplying warm low humidity air.

Air at a certain temperature has what is called relative humidity. At a certain temperature and relative humidity air has what is called the dew point. Any surface below this temperature will produce dew. The warmer air is the more moisture it can hold so warming an air mass with a certain amount of water will have the same absolute humidity but it will lower relative humidity. When the relative humidity reaches 100% the air can no longer hold any more water unless it is warmed.
 
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Jmolan

Member
Yes that is what I want to engineer, very simple air intake/cabin air intake. My heater is under the passenger seat, I will get a hole in there somewhere. Make sure the box is air tight, and plumb something simple like a PVC valve.

Auto's all have outside air/recirc buttons. You would never get your windows to clear on record I bet.

When the dew point and temp match we get fog. (Is a constant in the Aleutians in summer)
 
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surlyoldbill

New member
The best way to stop overnight condensation is to stop breathing while you sleep.

A small enclosed space like a van is going to be almost dripping with respiration after 8 hours of 1-2 people breathing in it. A moving vehicle vents some of that through the small holes built into the body, but a stationary van does not have the airflow.

Some sort of dehumidifier would help if you can't get the perfect temp/humidity ratio via heaters and vents and other stuff.
 

Graphite Dave

Dave Orton

Bobnoxious

Adeptus Trollarium
Window coverings. [/B]

Having recently purchased a Juki sewing machine for the purpose of sewing window coverings, what and where is the material called and purchased. And what is the proper name for the edging. Very nice BTW!

Bob
 

Midwestdrifter

Engineer In Residence

mdhutch2

Member
I've been using the same dehumidifier that Dave mentioned for 2 years now, but only while we are at home and on shore power. It works very well and produces several pints of condensate a week. I also heat the van to about 45-50 degrees so the air can absorb a little more moisture. There is never any condensation on the windows, in the walls or under the flooring. I never really thought about using it on the road because the built in a/c is such a powerful dehumidifier. I use the a/c full time in the winter whenever we go any where. Just set the heat where you want it.

All the vans I've ever had here in Seattle have developed a lot of water inside by the end of a winter just through a daily heat/cool/condense cycle and there was no good way to dry them out. Before the Sprinter I didn't have air conditioning in any of them. Now when we are on the road we tend to drive at least a few hours on more days than we sit still, so the van's a/c does a really good job of drying things out.
 

Jmolan

Member
This is the link she used to make the covers. We bought the foil at Home Depot and the ""ironing board cover" material at a sewing store or material store.
My wife is a long time seamstress, and she did not enjoy making these. The edging was a pain I guess. I helped cut out and hold, and feed her beers.....:)

We tried magnets and never got them strong enough. The suction cups have proven easy to use and very secure.

http://roadtreklife.blogspot.com/2013/03/diy-reflectix-window-insulation.html
 

Jmolan

Member
Follow up, I cranked the heat up today, and set the fantastic fan on low suck in back. I felt plenty of fresh cold air coming in through the fresh air vents from the dash. With my heater under the front passenger seat, this will work for now. Dry things right out!
 

Aqua Puttana

Poly - Thread Finder
Thanks for the insight.

... The edging was a pain I guess. I helped cut out and hold, and feed her beers.....:)

...
I picked up a PVC inflatable boat for good price because it needed repairs. Research showed that my Hypalon patch materials wouldn't work. I decided upon HH-66 vinyl cement for the many patches. It worked great.

I've since used the HH-66 to repair foul weather gear and fabric repairs like our RV mattress covering and a 2nd row passenger seat my dog tore standing with his claws for grip. It sticks very well to fabric. Not always pretty, but strong.

It may work to stick the two pieces of fabric together around the edges and then sew the edging on afterward.

:2cents: vic
 

hein

Van Guru
What I bought to try this winter:

https://www.eva-dry.com/dehumidifiers/eva-dry-1100-petite-dehumidifier/

For an additional $12.95 you can buy a 12 volt DC cord.

Works well in our laundry room so expect it to work in van. In my case I do not heat the van at night and stay warm with a 12 volt DC heating pad. Want to be stealth without heater noise.
These little dehumidifiers based on the Peltier device work great. I have one running in our van every winter whenever it sits outside. Here's one that you can run directly on 12V DC.

https://www.amazon.com/dp/B00MQ81BLG
 

Jmolan

Member
Thanks for the insight.


I picked up a PVC inflatable boat for good price because it needed repairs. Research showed that my Hypalon patch materials wouldn't work. I decided upon HH-66 vinyl cement for the many patches. It worked great.

I've since used the HH-66 to repair foul weather gear and fabric repairs like our RV mattress covering and a 2nd row passenger seat my dog tore standing with his claws for grip. It sticks very well to fabric. Not always pretty, but strong.

It may work to stick the two pieces of fabric together around the edges and then sew the edging on afterward.

:2cents: vic
Yes, will keep that tip in mind. We used a good grade of 3M spray on adhesive to stick the fabric layers together. I failed to mention mama wanted a few "colorful" covers also, which took 3 layers of material, but they do jazz it up a bit...:)
 

Jmolan

Member
These little dehumidifiers based on the Peltier device work great. I have one running in our van every winter whenever it sits outside. Here's one that you can run directly on 12V DC.

https://www.amazon.com/dp/B00MQ81BLG

Thanks for that. Living in Bend Ore. is quite dry, and we drive the van daily (one reason I chose a 4x4 Sprinter) about the only time we need the drying effect that goes beyond what the AC can give us, is when we are camping or skiing. After tracking in lots of wet clothes and gear having a hot air system that circulates hot dry air really kicks butt....:)

I looked at the humidifier you linked, never did see a way to get 12 volt to it, I probably just missed it. I did notice not so good reviews. Screen Shot 2016-10-17 at 9.57.06 PM.png
 

Graphite Dave

Dave Orton

GaryJ

Gary
Dave,

What's the listed DC output voltage/amps on the plug-in 110AC converter?

Thanks, Gary
 

Aqua Puttana

Poly - Thread Finder
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GaryJ

Gary
From the page posted.

"Additional specifications of the EDV1100 includes: a power adapter of 9V DC 2.5AMP, power consumption of 22.5W,"

vic
With the optional 12V cord, I wonder how the unit will like getting 14+VDC with the house battery getting a solar charge?

Gary
 

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