Condensation on windows

[mixxedbagg]

Sort of dropped this thread, but I have an additional question. We have no bathroom vent or air exchanger, and that unit on my furnace turned out to NOT be a humidifier. So, I've been limited in options, other than run the hood vent in the kitchen and let some air in through one of the basement vents.

I think we need to get a dehumidifier to run on the main floor. The smallest one I saw at the local fleet store was a 30 pint. That seems like a whole lot of moisture to remove...and kind of spendy. Anyone know enough about dehumidifiers to guess if I could get away with a smaller unit? My house is quite small. Also, does placement matter much or can I tuck it away in any available corner and expect that the air on the main floor will mix regardless?

[delcecchi]

It will only remove the 30 pints per day under specified conditions. Typically the new ones have a humistat that you can set. So it comes on at 60% and goes off at 50%. And the lower the humidity the less water it can remove per day. So, other than price, the 30 pint unit will do just fine.

[JohnMickish]

No bathroom vent can be a huge contributer to moisture in the house, especially if long hot showers are taken.

I think a dehumidifier is about your only realistic option.

[FishLocker]

Sort of dropped this thread, but I have an additional question. We have no bathroom vent or air exchanger, and that unit on my furnace turned out to NOT be a humidifier. So, I've been limited in options, other than run the hood vent in the kitchen and let some air in through one of the basement vents.

I think we need to get a dehumidifier to run on the main floor. The smallest one I saw at the local fleet store was a 30 pint. That seems like a whole lot of moisture to remove...and kind of spendy. Anyone know enough about dehumidifiers to guess if I could get away with a smaller unit? My house is quite small. Also, does placement matter much or can I tuck it away in any available corner and expect that the air on the main floor will mix regardless?

You have received a lot of good advice.

Put in a vent in your bathroom and run it when you shower, and run the cooking exhaust fan when cooking with water.

If you still need to dehumidify in the winter you may need to check ground water infiltration. Not always water, but moisture wicking from the concrete can still put lots of moisture in the air. Make sure your sump pump works and the basket is empty for the winter. Also check your dryer exhaust hose is still hooked up and not leaking moist air into the laundry room.

Dehumidifiers can be set for how much moisture to remove, and your example would max at 30 pints per day.

Your catch 22 is that warmer air holds more moisture, so the fastest way to dehumidify is to put your unit on the top floor with the warmest air. But the easiest way to run it without having to monitor/dump is to put it in an open area in the basement with a garden hose draining your tank into the floor drain so you never have to empty.

Quick fix to save the wood is to use window plastic, and I always suggest the 3M tape as the cheap tape leaves sticky residue that is a real pain to get off and collects dirt.

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Here is an excerpt from last years reply to someone elses condensation issue. If your thermostat is set cooler than 70 degrees then you will need a lower humidity setting as cooler air supports less moisture before precipitating out.

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Condensation (inside or out) is just a simple fact of dew point, not defective windows. Your window surface will be cooler than your room temperature all winter long. If you run a humidifier, or even boil water while cooking, you can put more moisture in the air than can be suspended by the rapidly cooling air that comes in contact with the window surface. The colder the air, the less moisture it will hold before precipitating out as condensation. This is why your bathroom mirror also gets condensation after showers...the mirror is cooler than the moist air from the shower. Here is somehting from the U of MN

The University of Minnesota has developed guidelines for the minimum recommended humidity levels for houses. Based on a 70ºF interior room temperature, engineering studies established the following guidelines:

Outside Temperature Inside Humidity

20º to 40ºF Not over 40%

10º to 20ºF Not over 35%

0º to 10ºF Not over 30%

-10º to 0ºF Not over 25%

-20º to –10ºF Not over 20%

-20ºF or below Not over 15%

These guidelines do not guarantee that condensation will not appear on mirrors or windows.

The building trades actually are lower yet, but they are also guarding against mildew and mold in insulation behind walls etc. Human skin is most comfortable at about 30%, and feels dry and/itchy under that.

[BartmanMN]

3M window film is the ticket for me on my windows that Face North and North West.

I do need to sand and refinish many windows this Summer. I keep putting it off, since I really don't like to do that type of thing, however it is time.

[soldoncass]

If there is no fan in the bathroom, there should be a window.....open the window a crack after showers. That will get some of the humidity out at the source, before it gets to the main part of the house. You should be able to get a fan in the ceiling from the attic, to help more.(won't be fun, but possible)

What kind of windows do you have? crank-outs, gliders(slide sideways), or double-hungs (slide up and down)? Double-hungs are easiest to put storms/combos on. Triple glazing(3 glass layers) is very helpful, and eliminates the hassle/mess of plastic every year.

A dehumidifier will help also(no matter where you put it), because basements are traditionally damp....that will leech its way upstairs also. Control bathroom and kitchen moisture, also and you should have a big improvement overall.

The way you described the unit on the furnace, I'm wondering if those tubes are part of a plus 90 furnace.....if so they don't burn up any moisture inside the house (like less efficient ones do). Every moisture source contributes to the totals.....so every little thing you can do will help some.

[mixxedbagg]

Wow. Thanks for all of the advice. I can definitely do some of this. Step one will be a dehumidifier. It will be on the main floor...in the bathroom, maybe?

I really don't think moisture is a problem in the basement. We don't have a sump or really any seepage. The blocks have been sealed several times with Dry Lock and my house is built on pure sand, so the water is gone quickly.

I can actually get my hands on a psycrometer at work, so I can measure the actual humidity...I hadn't thought of that. But, based on those guidelines, I'm sure I've never felt dry or itchy skin in this house...but always did at the last place I lived.

[upnorth]

OK...Not sure about this being factual, but doesn't double pane glass help condensation too? We get some pretty good frost on a few of our windows too, but the house doesn't seem humid. We have a humidity sensor and it shows a normal comfort zone.

[BobT]

Double pane certainly is better. Condensation occurs because the glass is cold and the water vapor in the house is condensing on the cold glass. The air between window panes adds a level of insulation so the interior pane isn't so cold and this reduces condesation. Triple is even better. Just adding a storm window helps but manufactured double pane windows are sealed and in some cases filled with gases that provide better insulating qualities.

[Tom7227]

You can buy a digital indoor/outdoor thermometer for under $20 and every one I've seen has a hygrometer as part of it. That's the jobberdo that gives you relative humidity.

[mixxedbagg]

Got the 30-pinter. I'll let you know if it makes a difference.

[soldoncass]

Good start...you will be amazed how quickly the reservoir fills up.

Double pane is better than single pane(single pane is SO BAD , it isn't even on charts), but triple pane is better than double. When I changed my windows 20 years ago, I put in double-hungs with a combo storm on the outside.....never get frost/condensation on them. However the bedrooms have crank-outs for egress, and they get a little frost on the bottom when it is really cold out...even after we added another glass in the screen slot.

[delcecchi]

Glass in the screen slot? Is that something that is off the shelf, or did you make it special?

That is a great idea, and I had never heard of it before.

[soldoncass]

"normal comfort zone" doesn't tell you much at all, too generic, and way too many variables.Just the evidence of frost build-up proves the existance of too much humidity inside for the style/kind of window you have. The only things to do are: improve windows or lower humidity.....or a combination of both.

I located that chart I mentioned before, but don't know how to post it. If someone is willing/able to do that, let me know your e-mail address, and I'll send it to you. Thanks.

[soldoncass]

Had them made, same size as the screen.....just switch them in the winter. Crank-outs always have the screen inside, so it is easy to do.

[MuleShack]

Not sure if i read this or not in this thread, but our house has the forced air, the whole house recirculation system and a humidifier with the wall setting.

No matter what setting I have it at, if I leave the insulated blinds down on a window i will get frost on the lower part of the window. Mainly due to the room heat not getting to the window for an extended period of time. When the blinds go up in the morning, then no problem.

If your windows are freezing up with no window coverings, then there is a lot of moisture.

[mixxedbagg]

I have seen some improvement with the dehumidifier. It seems to take maybe a half gallon or so out of the air in a day. It has a gauge that displays the humidity in the house which as pretty much hovered from the mid-30s to the low 40s. That doesn't seem excessive to me, but maybe it is--it's at least high compared to what a few of you have posted.

The humidity in the house really spikes when someone takes a shower, so I tried rolling the dehumidifier in the bathroom then, and it really made a difference...the mirror didn't even fog. I'm hoping a few more days will get us on top of the humidity in the house and it won't be such a problem. I have noticed the condensation height has receded since running this.

[Tom7227]

The temps have warmed up and so the air is able to hold more moisture. Acceptable levels in the house according to the able posted earlier is much higher than last week with the cold weather. Come this weekend when it hits 32 we'll have fog and excess moisture again.

[mixxedbagg]

Thanks for the responses and thanks for the chart Dale. I think the dehumidifier is having a positive effect as the windows are pretty dry right now.

[harvey lee]

I have an air exchanger and a dial mounted on the wall for adjusting. I can put my humidity in the house about where I would like it.

It is typically on average about 25.

I never have moisture on my windows or frost and if I do have some moisture, I simply turn down the humidity.

It did take almost one whole winter season to get to know how to adjust the exchanger just right but she works great now.

[reddog]

If you want to get on top of the humidity fast, just flush the house of its warm air and start over. Thats the simplest and quickest way to get it done. Start at the windward side of the hosue and open the ddors and windows and work your way around. By the time you get around, its time to close them. Youre not cooling the mass of the house, so the furnace recovers quickly, as dry air heats faster and easier than moist air.

[soldoncass]

Here's the chart I mentioned.