Condensation on interior windows

[alkco1-rts]

What is the best way to eliminate and prevent condensation on the inside of the windows. We are on the Oregon coast  and the outside temperature is about 50 degrees and the humidity is high.

Leroy

[Dreamscape]

Hi Leroy,

What part of the Oregon Coast are you visiting? I used to live in Salem and always enjoyed the coast, some beautiful country.

With regards to humidity it all depends on what kind of heat you have and how much moisture is in the air. Also it helps to have insulated windows to keep the transferance of outside and inside temps down to a minimum.

Good Luck,

Paul

[WEC4104]

Stating the obvious, the condensation is the result of the high humidity inside the bus, and the temperature of the glass being below the dewpoint.  For starters, let's talk about the humity level in the bus.  Do you have a propane stove?  One of the byproducts of burning propane is water, which gets added to the air.  Cooking with propane adds extra moisture to the air and is the fastest way to fog your windows. Anything else adding extra moisture (towels drying in the bathroom, water boiling on an electric stove, baths/showers)?

If the source of the condensation is just the high humidity in the Oregon air, and not self-induced, that leaves two other areas to explore.  The first is to try to "dry" the air inside the bus using some means. I don't know of anyone running a dehumidifier in their bus, but if shore power is available, I suppose it might work.  An air conditioner will also remove moisture, but if the air temp is 50, I'm guessing that is something you won't be doing.

Lastly, let's talk about the windows themselves.  The condensation is forming where the cold glass meets the wet air.  Replacing all your windows with dual pane insulated glass would of course help, but at major cost. Of course, if you could heat the glass (think rear window defroster wires) that would solve the problem also. Again, most of these options have considerable expense.

If you are looking for a small improvement for a small investment, you might consider trying a coating applied to the window.  Your local auto parts store will have bottles of Anti-Fog liquids that are for the insides of windshields.  It is usually on the shelf next to the Rain-X stuff.  I like the Rain-X product, but would not recommend it for this use.  Rain-X encourages moisture beading, and may actually make your situation worse. Instead get the sister product that states it is for anti-fog.  This may or may not help, but I think I would try it on one window and see if it makes a difference.

[Bob & Tracey]

We find leaving a roof vent open helps a lot.

Bob

[HighTechRedneck]

If cooking with propane, I've read that using an externally vented cooktop ventilator while cooking helps a lot (also helps with the heat of cooking in the summer as well).  If heating with propane, an externally vented heater makes a big difference.

[buswarrior]

What works quite well, if you don't mind the energy use...

Put your AC and your furnace/heaters into competition with each other.

As long as you get the interior up into the 70's, and it is above freezing outside, the AC will dry you out.

On those kind of wet cool days, I used to set one roof air on low AC and the other roof air on high heat on an old command vehicle I once had charge of. Aimed the discharges at one another into the middle. If cooler, adding some more BTU via a cube heater was done.

Engineering a bus conversion HVAC to do this automatically is amongst those dreams for the next chapter of some bus conversion... BTW, the stock coach HVAC will do the same thing.

happy coaching!
buswarrior

[Lin]

Good ventilation when using anything that produces moisture like showers, cooking, etc.  If you are using an unvented propane heater, consider if you are willing to accept the moisture issues.  A small dehumidifier would work.  A dehumidifier works similarly to an air conditioner in that it cools the air to extract the condensate, but then re-heats the air with the condenser.  You end up with dryer air that is a little warmer.  What Buswarior suggests is really the same thing using two systems and more energy.  However, if you try that with an unvented propane heater, you are going in circles.

Oh yeah, people are another big moisture load.  Encourage everyone to stop breathing.

[TomCat]

We find leaving a roof vent open helps a lot.

Bob

I'm with Bob on this one...leaving the roof vents cracked open, even as little as a 1/4 inch should relieve your condensation issues.

HTH

Jay
87 SaftLiner

[fraser8]

I installed a portable dehumidifier I bought at the building supply. The first night we ran it we emptied almost two gallons of water out. I turn it on when we go to bed and in the morning I'm surprised by the amount of water that needs to be dumped out. We have no condensation on any windows and the environment is much nicer. We live on the Wet Coast so condensation is always a big problem.

[niles500]

I'm with fraser - the dehumidifier will also help your A/C in summer muggy weather - HTH

P.S. most units have a hose to bypass the reservoir which eliminates having to empty the units constantly - place it on the counter and run the hose to the sink - FWIW

[NEO/Russ]

While my rig is parked I didn't want the wood to swell or the interior to get musty so I searched for a de-humidifier.  I found a 40 quart at Wallyworld that that was too big for my tastes.  At Lowe's I found a 25 quart and as I recall it was like $174, plus tax.  It has a name brand, but like everything else electronic today, made in China.  It is small enough to sit on the kitchen counter with a hose going into the drain.  It has a gauge and can be left on continuously or timed for 2 hrs or 4 hrs.

[JohnEd]

Guys,

I guess a dehumid is the optimum.  I wouldn't throw away all the "distilled" water, though.  Keep it for adding to the ethy gly anti freeze at change time.  Also, for the windshield washer so the tips don't get all clogged with minerals and same for the rad misters.  Steam iron water comes to mind.

I did the window problem different:  I put shrink film on all windows and they never sweat again.  I leave the stuff on some windows for a couple years.  It is hard and cleans like glass if you are careful.  The name of the product Frost King and all the home stores have it.  Not particularly expensive.  I put the thin 1/8 inch square foam self sticking foam to the edge of the metal window frame and then stick the film to the wood around the window.  That prevents conden from forming on the film that is stuck to the frame without foam isolator.  Buy a humidity monitor at Radio Shack so you can "see" what the effect is of what you are doing.

I kept a vent open 24/7 to dump humid.    One person aspirates a lot of moisture.  Now two people and a couple dogs and you have a small mtn stream.  Add to that cooking moisture and golly Batman.  You have to "dump" the inside air every once in a while and watch the meter for the timing.  Don't get things too dry.

The widow film also make a world of difference in the insulation and makes heating and cooling much, much easier....all year long.

HTH,

John

[alkco1-rts]

Thank Paul and others

I live in Salem, OR and in joy the coast. Thanks for all the comments it was very helpfull

Leroy

[Dreamscape]

Hi Leroy,

My folks live in West Salem across and down the road from Salem Towne. Small world huh. I go up there to visit them when I have to work out of our home office in Vancouver WA. Would be nice to meet you one day. I used to live on Battleground road and really liked the area, but God had other plans for my life! My younger brother just sold thier place at McNary Golf Course and moved to Sisters, and he's retired!

I hear the weather has turned south and it's getting nasty, so stay dry!

Take Care,

Paul