Windows - Condensation

[lindy rig]

Just moved in to a 10 yr old house with Anderson crank out windows. Are there any tricks to reducing condensation?

[reddog]

Reduce the relative humidity inside the structure or increase the surface temperature of the glass.. Reducing the RH, can be done with some sort of mechanical ventilation, either run your bath fans (marginal at best) or increase the ventilation rate of your houses HRV/EFV etc. Shut off or reduce any humidifyers you have running to try to find a balance in your house..Increasing the temp of the glass, doesnt mean raising the temp of the house, it means exposing the glass to more of the heat inside the house, by either opening drapes, or moving air across the surface.

With that said, even the best windows in the best structure built nowadays, will have condensation under the conditions we are experiencing now.

If the condensation is excessive, look for the source.

Damp basement, uncovered floor in crawlspace. excessive plants, long showers, too many kids showering, etc.

[leechlake]

our house is the same age, same Andersen windows. I'm in the millwork business so keeping the right relative humidity in the house during the Winter especially is on my mind to keep the hardwood floors and other woodwork happy. I shoot for 30-35% RH (google RH at certain outdoor temps that RH% should actually be lower at lower temps), I balance it with the humidifier but also the air exchanger. Ideally in the am you want just a few drops of condensation on the bottoms of the windows. Ideally doesn't always happen. Take all screens off the windows in the Winter, these increase air getting to glass.

My kids shut the blinds at night and shut their doors. Their windows can be pretty icy. Ideally the blinds would be open or if they shut them they should open them in the morning and turn the ceiling fan on.

The better air flow you have at the correct RH the better your windows will fare. Sometimes you just need to towel them off when it's super cold to avoid the water pooling on the sill and ruining the finish and eventually decaying the wood.

The bathroom with the shower can take a beating, we have two fans in our bathroom and you just get a lot of condensation on cold days.

[BoxMN]

Leechlake, when you do get some condensation, is there anything you can do to help prevent the finish from getting "water stained"? Like wash down after winter with some oil or cleaner or something? I recall my parents anderson windows getting blackish over the years. I have new (6 yr old) Marvin, and though we now have the air exchanger set right to get very little, I want to avoid those "black corners" if possible. Thanks!

[yoppdk]

We've experienced a LOT of condensation this year ... I've been trying to keep up with it by wiping moisture from windows, but even today with -9 temps in the morning it's pretty evident. I've noticed that the outdoor relative humidity is still pretty high and i guess that is part of the problem. When it gets this cold it seems the humidity is usually pretty low. But our's reads 97% right now (9:30 am). It's usually uncomfortably dry but not so this year, at least not so far ...

[#fishhunt#]

Try putting the 3M window plastic insulator over them. I don't get any that way. Also if you pull the shades down teh air flow behind the shades is bad. Turn a small fan on in the room may halp also.

[Tom7227]

Found this info. In order to keep track of things you need to get a hygrometer - which most folks call a humidity gauge. You can get one fairly cheap as they often are included in any electronic indoor thermometer. As indicated you need to adjust your indoor humidity as the temp changes. My older April Air has a device that allows me to change the setting but doesn't adjust it automatically. Check out your setup.

"The following list, supplied by the Minnesota Department of Public Service, is based on a double-glazed window and an indoor temperature of 70 degrees. You will notice that the lower the outdoor temperature, the lower the indoor humidity should be.

If outside temperature is 20 to 40 degrees, humidity indoors should not be more than 40 percent.

If outside temperature is 10 to 20 degrees, humidity indoors should not be more than 35 percent.

If outside temperature is 0 to 10 degrees, humidity indoors should not be more than 30 percent.

If outside temperature is 10-below to 0, humidity indoors should not be more than 25 percent.

If outside temperature is 20-below to 10-below, humidity indoors should not be more than 20 percent.

If outdoor temperature is lower than 20-below, inside humidity should not be more than 15 percent.

[leechlake]

Box-

I sand the sill then use one part bleach to three parts warm water. Use a toothbrush and get in the corners. Let it dry and then reseal with polyurethane.

Do it in the Spring when you notice it being needed.

[BobT]

If your house is only 10 years old, there's a good chance it is too well sealed and this is causing your problem. It is not an uncommon problem as we strive to prevent heat loss. One of the best ways to regulate and control this is to install an air ex-change system.

Whatever you do, if you don't control the humidity, your windows will get damaged forcing you to repair them.

[311Hemi]

I'm in the millwork business so keeping the right relative humidity in the house during the Winter especially is on my mind to keep the hardwood floors and other woodwork happy. I shoot for 30-35% RH (google RH at certain outdoor temps that RH% should actually be lower at lower temps), I balance it with the humidifier but also the air exchanger. Ideally in the am you want just a few drops of condensation on the bottoms of the windows. Ideally doesn't always happen. Take all screens off the windows in the Winter, these increase air getting to glass.

I agree with this.

Lindy, you will need to turn your humidifier down (or off) when it gets cold outside like it is now. You can turn it back up when it warms up a bit. It's kind of a constant monitoring thing to watch to keep woodwork happy. In my brand new house I have condensation on most of my windows as well (Marvin Integrity), it's just that the humidity inside is too much compared to outside temps. I had turned my air exchanger off for a few days when it was warmer out to try to get more moisture in the house (to keep at or above 30%), but turned it back on today to try to dry it out a little more until the temp warm up.

For the hardwood floors, ideally 30-40% is what you want during the winter. Because of my hardwood floors I have been monitoring my upstairs and downstairs humidity levels, and upstairs I am at 30% (28% downstairs) and still getting condensation on the windows today. I may have to try to get down to somewhere between 25%-30% temporarily to get rid of the condensation while it's cold out, and then get it back up around 30% when it's warmer. My goal will be to keep it above 30% as much as possible when I can, but temporary cold spells well need to be adjusted for.

I think the ranges Tom posted above are a good reference point. My dad had read me similar numbers that he got from his humidistat on his HVAC system.

Only bad part about it is the dryness of the air. My daughter sometimes gets nose bleeds when it's this dry, so I will run a humidifier in her room some nights.

[delcecchi]

I have another similar question. We had our breezeway remodeled and a new storm door put on. The other storm door is old.

The new one gets big time condensation on it. The old one not a drop. Any ideas why? My theory is that the low-e glass in the new door somehow encourages condensation. Both doors are single pane. One faces sort of north and the other sort of south. Breezeway is not heated.

[reddog]

Surface temp of the glass could be a factor between the north and south doors, with the south being slightly warmer.

Could be positive pressure on one side of the structure and negative on the other, with air movement dragging rh to the negative side.

Or, it could be the low e surface. Interesting observation.

H2O doesn't like being in a vapor state. It's constantly searching for a condensing surface.

[lindy rig]

Good info, thanks guys, thanks Hemi. I am not having much of a problem downstairs, but upstairs it's pretty bad. Water pooling and ice forming. I did remove screens. But we are using shades at night and I noticed that makes it worse.

I do have a humidifier and air exchanger. Had the humidifier on around 35 for our hardwood floors as previous to this I noticed some gaps and shrinking. Guess I'll shut off the humidifier for awhile. Funny, somehow I thought a new(er) house would be less maintence. I don't think the plastic wrap is really feasible I have 50 XL windows.

With the ceiling fans is there a difference which direction is goes?

And what is the main purpose of the air exchanger?

[311Hemi]

Reverse ceiling fan direction in winter to great an updraft, can run at low speed. This will help force the warm air back down into the lower levels of the room.

Your air exchanger is used to being fresh air into the house. Today's houses are built tight so air exchangers are used to bring fresh air in and remove stale stagnant air.

Your floors are going to shrink in winter and you probably will see gaps. I see some starting to show on mine now. Just a part of loving with hardwood flooring. You do want to keep it above 30% when you can, but in these cold conditions I don't think you can without having condensation on the windows. We open the shades first thing when the kids are up to let the windows dry out. We have that same problem even with 26% humidity in the house.

Your air exchanger should have some setting that you have to adjust as well.

[delcecchi]

One additional thing. The previous storm door on the breezeway, pre-remodel, didn't ice up nearly as much. Maybe a little but not much that I recall.

Not a big deal, but I think it is the low-e glass. (talk about a waste, low-e glass for energy conservation on an unheated space.)(I don't think I would have saved much by special ordering regular glass, if I could have)

[amateurfishing]

If your house is only 10 years old, there's a good chance it is too well sealed and this is causing your problem. It is not an uncommon problem as we strive to prevent heat loss. One of the best ways to regulate and control this is to install an air ex-change system.

Whatever you do, if you don't control the humidity, your windows will get damaged forcing you to repair them.

we always get window condensation this time of year due to amount of cooking we do in kitchen, just one of the draw backs of a well sealed structure, if I knew how to limit it I would, all we have are ceiling fans & air exchanger and I don't think air exchangers are meant to be on during winter (correct?) or that would be bringing additional humidity into the home, right?

[dillon]

My house is about 8 years old and had such a bad window condensation problem that I was going to change them all out. This year I put on an addition and decided to also put in an air exchanger. My condensation problem is now gone. Before, when it got below zero, my windows actually frosted up. This morning it was -22 degrees and the condensation was only slightly noticeable...absolutely no frost.

With the newer houses sealed tightly, I think an air exchanger is a must.

[CAMAN]

we always get window condensation this time of year due to amount of cooking we do in kitchen, just one of the draw backs of a well sealed structure, if I knew how to limit it I would, all we have are ceiling fans & air exchanger and I don't think air exchangers are meant to be on during winter (correct?) or that would be bringing additional humidity into the home, right?

[Down Deep]

I would go with the 3m film. You keep the moisture away from your glass and eliminate condensation. I have first had experience with this method. I had my house resided and new Walsh vinyl replacement windows installed. Everything was sealed and insulated at the time of the installation. The first winter I noticed the condensation and applied the film. One thing you want to consider is the tape can pull the finish off when you pull it off, but it can also be installed around the edges of you trim. I you use a heat gun instead of a hair dryer the job will go fast.

Another thing you can try is run your ceiling fans on low.

[311Hemi]

Quote:

Incorrect, air exchangers are meant to run in winter. Some say they should be turned off in summer but I know people who do both and dont see a difference either way.

I definitely saw my humidity levels increase in the summer when the air exchanger was running.

[not_nuf_time]

I was going to mention, an air exchanger is really the only way to cut out the window frosting. We put one in about 10 years ago and never, or seldom get condensation now. The cost is around 2 grand, but far cheaper than window replacement so worth the cost. As a matter of fact I just orderd 5 windows that are wrecked from frost before I got the air exchanger, just those 5 Marvins $4000.00. As the old commercial goes, pay me now or pay me later.

[reddog]

85% outside humidity is a completely different animal at 90 degrees in the summer and -12 degrees in the winter. We probably still have 70 -80% outside RH right now, but when that cold winter air is brought in and warmed up, it expands in volume several times by the time it gets to room temperature. The RH remains static at lets say 80%, but the volume of air holding that 80% grows, so the RH/volume reduces down to maybe 15 or 20 percent by the time it gets to room temperature. That is why your house dries down so much in the winter with uncontrolled infiltration.

The single most quickest way to rid your house of excessive humidity is to simply open a window at the top of the structure, then open one at the bottom and let stack effect carry all the moisture out of the structure for a few minutes. Dry air is easier to reheat than moisture laden air.. it will only cost a few cents in heating costs to reheat the air you bring in, but the dehumidification that occurs will be substantial.

I have a 1928 farmhouse that I just installed 26 Marvin Integrity windows in in October. I have a point and shoot laser temperature/hygrometer. Just this morning, I shot the glass temps. Center of the glass pane was 61 degrees, bottom edge of the glass was 49. This is not a window problem, its called edge effect. The top edge was 55. (heat rises, even within a glass surface) This edge effect is what attracts humidity and causes it to condense. Once it starts condensing,(and possibly turning to ice), it will expand its range a round the sides of the window, primarily because it is cooling the glass surface more as it grows.

Find the source of the humidity and address it.

If you dont want to spend the money on a air exchanger, simply run your bath fans more.(assuming they are ducted to the outside, if not, then you will floor your attic with moisture laden air where it will condense on your roof sheathing) or, open the windows occasionally and let the humidity out for a short period of time.

[311Hemi]

One other important thing for those with air exchanger, make sure you clean the filters. Mine says to clean every 3 months. I recently cleaned mine and man were they dirty! Dirty filters do not help the HRV systems.

[crothmeier]

http://www.marvin.com/windows-and-doors/condensation/

If this is legal to post, its a good read, with information on combating this problem.

If you look up Andersen windows article, it says the exact same thing.

We've gotten alot of calls in the past two weeks regarding this issue.

[reddog]

Cause: Inefficient windows with extremely cold glass surfaces Cure: Install energy-efficient windows and doors. High-performance windows, such as those made with Low E II coatings with Argon gas, make the most of the sun’s heating rays during cold months and maintain a remarkable temperature difference between the indoor and outdoor panes of glass.

FACT: Installing new windows can potentially increase the amount of condensation, because of the inherent tightening of the structure that comes with improvements such as these. Where natural ventilation was occuring to lower the RH thru infiltration has now been short circuited with new, tight foamed in windows.

Cause: Moist air trapped in attic

FACT: Moist air in the attic will have no significant effect on a window inside the building envelope. In fact, the opposite is true. If you seal all your openings to the attic, )like changing out to new windows) you have effectively changed the dynamics of the house again, thus causing more trapped humidity in the living space and exacerbating the condensation problem you are trying to cure.

Cure:Seal around indoor light fixtures to prevent warm, moist air from rising to the attic. Install soffit vents to prevent attic rot, making sure to keep vents clear of dirt and garden debris.

Cause: Radiator or kerosene heat

Assuming by "radiator" they mean Hydronic heat, this is a sealed system, and will have no effect on the RH of the house. The only thing a radiator heat lacks is the air movement associated with a gas or electric furnace.. Kerosene... yes..

Cure: Use dryer sources of heat such as gas or electric furnaces.

Cause: Cooking and dishwashing Cure: Vent stove range hoods and dishwashers to the outside. REALLY, A vent for a dishwasher?

Cover pots while cooking.

Cause: Stale, damp air Cure: Install an air-to-air heat exchanger to vent moist air outside. Some air quality systems recover up to 97% of the existing warmth and energy to heat incoming fresh air.

Cause: Showers and baths Cure: Make sure bathroom exhaust fans are vented to the outside and use fans regularly.

Every time you do something to your house, it effects the dynamics of how the house is functioning prior to the improvements.

Changing out a furnace from a standard flue to an energy efficient, draft induced furnace will change how your house performs. other items that will change the dynamics of a house are.

Windows

insulation.

doors.

You can have a house that performs fine, (but is not particularly energy efficent) and change windows, doors furnace etc, and end up with a house that it rains in the attic on the first warm day of spring.

The house is a system, and needs to be addressed as such.. Ventilation is good, whether natural or mechanical. The problem with natural ventilation, is that there is no control over it. ON a windy day, you get lots of ventilation, on a calm day, not so much. Stack effect is a primary cause of ventilation also. Cold air enters a sturucture where ever it can, but stack effect (chimney) causes more cold air to enter lower if allowed to leak out with the warm moist air at the top of the structure, thru recessed cans, wire penetrations, attic bypasses etc.

Crothmeier.. You and I both know what Marvin means on the HSOforum they linked to, but to put it in such simplistic terms, takes it from what is thought to be good information, to maybe not so good, if someone were to address it to a T..