Condensation and ice on windows - help!
duluthjeff
10 years ago
Not strictly speaking a new home, but our builder told us to expect year-over-year improvement as the wood dries out. Instead we are experiencing more condensation and ice buildup on our windows than in years past. 4-year old 2900 SF very tight, well insulated home in Duluth MN. Running a Venmar HE 1.8 HRV at full blast continuously. Windows are well sealed, double paned low-e. This year, we are getting more condensation and icing whenever the outside air temp is Is our HRV too small, or am I doing something wrong? We are not generating more water into the air (cooking showering etc.) than in years past. Any ideas?
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10 years agoUser
10 years agoRelated Discussions
frozen condensation on storm windows
Comments (10)Heat always travels to cold and wet always travels to dry - (unless acted on by an outside force). Your windows are a prime example of that principle. In the winter, the outside air is cold and dry. Cold air does not hold moisture very well and no matter how dry your home may feel to you, it is still holding more moisture than is the air outside. That warm and moist inside air wants very badly to equalize with the cool dry outside air, so it is looking for a way to escape from your home. In the middle of summer, pull a can of something cold and frosty out of the refrigerator and notice how quickly the can becomes wet on the outside. This is condensation caused by the contact between the warm, moist summer air and the cold can. The surface of the can is below the dew point. Trying to stop moisture from forming on the can is impossible because it is some very basic physical laws at work. Unfortunately, those same physical laws are affecting your windows in the winter when you get moisture forming on the surface of the glass. Your leaky inside windows are like an open invitation for your nice warm inside air to go outside...and in the process, it is drawing lots of nice warm, moist air to the storm windows. The warm air is contacting the storms and, like the can out of the refrigerator, the glass surface is below the dew point of the air inside your home...thus, condensation on the glass surface. With a single pane window, when the temperature is 0 degrees outside (F), the face of the glass inside is only about 16 degrees. At 16 degrees, it doesn't take much moisture to cause condensation on the surface of the glass. BTW, the numbers I am using are center-of-glass measurements - edge readings will be lower by several degrees. If you add a "tight" storm window, then the surface of the inside of the inside window may be about 40 degrees or so, when the outside temp is zero, but that outside storm is still going to be well below freezing. At 40 degrees, for example, it takes only about 6-1/2 grams per square meter of moisture in the air to reach the 100% RH level or dew point temperature - which is pretty close to the temperature of your windows. At that 6-1/2 grams of water per cubic meter an RH reading of only 30% at 75 degrees is sufficient to have moisture on your inside windows - at that moisture level. At 32 degrees it obviously takes even less moisture to reach 100% RH which will cause condensation and subsequently frost or ice on the storms. Ultimately, there are two things you can do to help prevent moisture from gathering on your windows first, you can attempt to increase the temperature of the windows to a mark above the dew point, and second, you can attempt to block the warm, moist air from reaching the glass. In order to raise the dew point of the windows themselves, you will have to assist your homeÂs heating system by using small fans or, even better, small forced air heaters, close to, and directly facing the glass. I suspect this is not a practical solution, except for maybe the very worst offenders. This "solution" should warm the inside glass enough to avoid moisture build-up, but at an obvious cost in your energy usage, but it may not do a thing for the water and ice build-up on the storm windows  only on the inside glass. As Guy suggested, the plastic window covering is probably the best possible "solution" for your situation. The plastic film will help to keep inside moisture away from the windows. Also, as Carol suggested, keeping blinds and curtains open will help a great deal control inside condensation, but that won't do much for icing-up storms, unfortunately....See Morecondensate/ice on interior window edge
Comments (1)It is condensation from the broad temperature differential and higher than tolerable indoor humidity. Even if the aluminum windows have a thermal break (foam insert) they are going to be your most conductive frame material and therefore get cold when it is cold outside. Cold surface + warm air = condensation. Most windows that are considered thermally broken are actually just insulated and not truly thermally broken. You can lower you indoor humidity and see if that doesn't fix the issue temporarily. I think we can agree that these are pretty irregular temps for Dallas....See MoreWhat's the deal-e-o? Ice & condensation on interior of windows
Comments (22)The argument that one spacer system is inherently superior to another or all others is ripe with the possibility of misinformation, misunderstanding, and certainly a great deal of emotionalism. Each system has its proponents and its detractors. In the past, polysulfides, silicones, butyls, and other sealant or adhesive materials were used as the primary (and often only) seal for many aluminum spacer systems up to the advent of the original warm-edge spacer systems. Many of these same aluminum spacer systems have shown extensive seal failures when analyzed possibly as high as 6% - 10% seal failure rate at 10 years for some of these units. Virtually all newer spacer systems, including SuperSpacer, use a dual seal system which in the case of the SuperSpacer system includes, primarily, a hot-melt butyl sealant as the primary moisture or gas seal and an acrylic-adhesive as the primary structural seal. Unlike other systems, however, SuperSpacer is "reversed" in that it places the structural seal inside the IGU (between the lites) and the primary or moisture seal to the exterior of the structural seal. Does reversing the moisture / structural seals (compared with other systems) make SS an inferior product? No, not in the least actually SS outperforms every other system on the market, including TPS, in energy performance numbers given that Super Spacer is generally only about ½ to one degree better than TPS at the edge. The hot melt butyl primary seal used with the SuperSpacer system has a very specific application temperature range of 275º 325º. If the applied material is outside of this range, then the P1 chamber testing can be significantly reduced to as little as two to three weeks to seal failure. What happens in the field in this case? In addition, SuperSpacer allows the use of polysulfides, polyurethanes, and even silicone as the primary moisture seal. The problem is that none of those options is impervious to air and air/moisture intrusion into the airspace may be a possibility with the use of those materials. Edge Tech advertises that their system goes 80+ weeks in a P1 test. They advertise that the "metal" (stainless Steel) systems go 40+ weeks in the P1 chamber in the same marketing brochure Edge Tech also made the claim that none of the other systems tested lasted more 40 weeks. What they dont explain is that the "40+ weeks" of the metallic system was actually 80 weeks for a PIB / silicone dual seal spacer system. Some industry folks suggest that one week in a P1 chamber is equal to one year in the field while other folks suggest that one week in a P1 chamber equals one week in a P1 chamber - and nothing else should be inferred. However, after 80 weeks or so in the P1 chamber the bond between the glass and the seal begins to break down possibly as much from glass deterioration as from spacer material failure. Am I slamming SuperSpacer? Again, not at all. When manufactured to strict quality control standards and exactly as specified by the manufacturer, then SuperSpacer really is a very good, even superior, product. What Edge Tech does really well is market their product(s). They have what appears to be an excellent, even superior, product; but they also have a marketing program that totally kicks butt. They have opened areas of discussion that really didnt exist prior to their introduction of itthey have emphasized SSs inherent advantages while ignoring any potential disadvantages (which is what marketing folks do, of course). They have invented new ways to categorize window spacer systems in some ways they have introduced the idea of IGU spacers to the general public. Energy performance and durability are what these things are ultimately about. How do they compare? At the edge of the IG, SuperSpacer is the best performer with TPS (Thermoplastic Spacer) second by about a degree or so. Cardinal Glasss XL stainless steel system (there are a couple of different ones on the market, but Cardinal is the largest manufacturer) is about two degrees or so lower than TPS a bit better than Swiggle. Drop another degree or so to Intercept and about another 6º to 8º for aluminum. Ultimately, using a LowE coating will have a much greater effect on the overall unit temperature performance than does the choice of which one of the "warm edge" systems. Of course using a LowE coating with SuperSpacer and with Swiggle still keeps SS a couple of degrees warmer at the edge, but these are also ratings of the "raw" IGU so what happens when the unit is in a frame? Well, how about this for thought from a joint Canadian and European study on the performance of various edge systems: "Conclusion The thermal resistance of the spacer bar material influences the glass temperature at the edge-of-glass region of an IG unit. Based on the limited testing performed at IRC and computer modeling at EMPA Switzerland, the spacer bar with the highest thermal resistance shows the warmest glass temperature on the warm side and the coldest temperature on the cold side of the glass at a distance 5 to 60 mm from the edge of the IG unit. But the effect of the type of spacer bar on the overall thermal resistance (and tote heat loss) through windows depends heavily on the window design and material. Therefore, the full impact of thermal characteristics of the spacer bar material on the thermal resistance and the condensation resistance of a window should only be determined by testing complete window assemblies." Heck of a concept testing complete systems rather than independent component testing to determine how the system will perform. Durability some folks will suggest the idea that desiccant is used in most spacer systems in order to hide seal failure. While it is correct that the desiccant used in these systems could absorb moisture in an IGU so that for many years there would be no evidence of a seal failure, a catastrophic seal failure, like those seen in some older single-seal, organic-seal, IGUs would overwhelm the desiccant relatively quickly and could cause the window to fog as well but this is much less likely with todays dual seal systems be they non-metallic, metallic, or otherwise. But what if there is a seal failure? Well, the desiccant used in these systems (except TPS which includes only 4% desiccant in its structure) could very well prevent moisture from forming inside the IGU for many years even with a minor seal leak and to play devils advocate, so what? Well, if the window was argon filled (which is true of half of IGUs manufactured today), then the argon will escape possibly to be replaced with air. But, if only half of IGUs today have argon fill then what about a window with no argon that has a "leak" as noted what happens to the energy performance? Basically nothing. There is virtually no difference in the energy performance numbers of an IG unit sealed or unsealed. If the desiccant was sufficient to maintain the interior without condensation, then the LowE coating would be safe as well. As I said though, I am playing devils advocate and real world numbers as well as lab testing are very specific that seal failure numbers in newer systems are extremely low. Kommerling TPS claims that they have never had a failure. EdgeTech claims less than 1% over 20 years and Cardinal advertises less than a quarter of a percent using XL for 20 years. Swiggle is higher, Intercept is much higher. Depending on the source of the information, Intercept may be as high as 6% (or more) at 10 years failure rate. This is primarily a manufacturer rather than a product issue, but it has become a very serious problem for several major window companies. And speaking of argon, filling an IGU to 100% with argon will improve performance by 16%. 50% argon fill improves performance by 8%. 25% argon fill improves performance by 4%. Notice the trend?...See MoreCondensation on Anderson windows
Comments (5)Okay, this is a really long answer. I have posted this same answer to this same question previously - but it is a really good question and it becomes a common question this time of year... The reason that you have moisture on the inside surface of your windows is because the temperature of the glass is below the dew point temperature of the air in your home. In order to stop moisture from forming on the surface of your windows, you either have to raise the temperature of the glass to a level above the dew point temperature of the air in your home, or else you have to lower the dew point temperature of the air to a level below the temperature of the window. Unfortunately, suggesting those two solutions is often much easier than actually being able to accomplish either one. I am going to include a post about window condensation that I wrote and posted on a different forum in THS. It is really long and even has a little math in it...but I think it does an okay job of explaining some real basic information about window condensation. -------------Window condensation -------------- The reason why there is condensation on the interior of your windows has a really simple explanation the surface temperature of the window is below the dew point temperature of the air in your homeÂthatÂs itÂa very simple explanation. Unfortunately, the reason that the window surface temperature is below the dew point temperature can potentially become somewhat more complex, but I am going to offer a few thoughts and even throw in a few numbers that I hope might help your situation. In the summer, when you pull something cold and refreshing out of the refrigerator, and the air is warm and humid, that cold and refreshing beverage container suddenly and quite magically becomes instantly wet  just as soon as it is exposed to the air. What has happened is that the temperature of the container fresh from the refrigerator is below the dew point temperature of the air  which has caused condensation on the outside of that container. What happens to your windows in the fall and winter is that the surface of the glass is below the dew point temperature of the air in your home  which is causing condensation on the surface of that glass. Dew point is defined as saturation vapor density...or put in simpler terms, when the air reaches 100% relative humidity and can hold no more moisture. Relative humidity is, well, relative. Relative humidity is a comparison of the actual vapor density versus the saturation vapor density at a particular temperature. Basically, dew point is 100% relative humidity or the point where the air - at that temperature - is no longer able to hold any more moisture. If the air has reached vapor saturation (100% relative humidity), then the air will release moisture...be it on the outside of that cold beverage container in the summer time, or be it on the interior glass surface of your windows in the winter time, it makes no difference. If the surface temperature happens to be below freezing, then that moisture becomes frost or even ice. In order to stop condensation from forming on the surface of a window, you either have to lower the dew point temperature of the air in your home to a level below the dew point temperature of the window surface, or you have to warm up the window surface to a temperature above the dew point temperature of your home, or a combination of both. Lowering the relative humidity of the air in your home MAY have absolutely no effect on controlling window condensationÂand I bet that that statement is a bit of a surprise to some folksÂit is true however. There are two ways to lower relative humidity  increase air temperature or decrease moisture content. If you increase the air temperature you will lower the relative humidity but you will not change the dew point - which is based on the amount of water vapor in the air and is not based on the temperature of the air. The amount of moisture in the air is measured in grams per cubic meter, which is kind of nice for our metric folks but not so nice for our non-metric folks; but the metric version is much easier on the calculator than the English version. However, in the interest of making this stuff easier to understand for all of us non-metric types, I am going to use Fahrenheit rather than Celsius temperatures in the calculations. Okay  consider your home at 65 degrees F and with a relative humidity reading of 40%. There are 6.25 grams of water in a cubic meter of air in your home in that particular scenario - which then equates to a dew point temperature of 38 degrees F. So at 38 degrees the air will be at 100% relative humidity or at saturation vapor density. Now, if your neighbor keeps her house at 75 degrees, but she also has 6.25 grams of water per cubic meter in her air, then the relative humidity in her home is 29% - versus your 40%. But, and hereÂs the kicker, the dew point temperature in her home is still 38 degrees. While the relative humidity in her home is much lower than is the relative humidity in yours; if the surface temperature of the windows in her home is 35 degrees she will have condensation on those windowsÂyet if the surface temperature of your windows is 40 degrees  only five degrees warmer  you will not have condensation on your windows. So, while her handy humidity gauge reads (correctly) only 29% RH  she has a condensation problem. While your handy humidity gauge reads (correctly) 40% RH  you donÂt have a condensation problemÂSWEETÂwell, for you anyway, not her. If your home hygrometer measures the relative humidity in your home at 60% while the temperature of your home is 70 degrees, you will have a dew point temperature of about 51 degrees  meaning that if the temperature of the window surface is below 51 degrees then you will have condensation - so now we talk a little more specifically about windows. The interior surface temperature of a single lite of glass, when the temperature outside is 0 degrees F and the inside air temperature is 70 degrees, will be about 16 degrees. Add a storm window on the outside and the surface temperature of the inside lite jumps up to about 43 degrees  a huge improvement. But these are center-of-glass readings and not the temperature readings at the edge of the window where condensation usually forms. A typical clear glass dual pane window is going to have center-of-glass temperature reading pretty much the same as a single pane with a storm  something that is often claimed (correctly) by folks who advocate refurbishing windows rather than replacing (something that I am not going into here  I am NOT advocating either replacement or restoration in this post. It is long enough and detailed enough already without opening that particular can-of-worms!) However, if that dual pane has a LowE coating and an argon gas infill then the center-of-glass temperature will be about 57 degrees  a 14 degree improvement over a clear glass dual pane or a single pane with storm window  but again, and more importantly, there will be a comparable edge of glass improvement as well, particularly if the IGU (Insulating Glass Unit) was manufactured using a warm edge spacer system. Also, the dual pane is going to have desiccant between the glass layers. Desiccant absorbs moisture keeping the inside of the dual pane system very dry. The advantage? If it gets cold enough outside, the temperature in the airspace between the lites can get very low. By keeping that space dry, it helps to keep the dew point temperature very low as well; something not always possible when using a single pane and storm window. Although a single pane with a good and tight storm window can help the interior lite to avoid condensation (when compared with a single lite and no storm), the storm window itself will frost up when the temperature is low enough  at a temperature usually well above the temperature that will cause the dual pane to ice up. It is unavoidable given the right circumstances So what does a window temperature of 57 degrees mean? Well, as I mentioned earlier a home kept at 70 degrees with a 60% relative humidity has a dew point temperature of 51 degrees so it is unlikely that there will be condensation problem on those particular windows despite the relatively high relative humidity in the home. But what happens to the dew point if you keep your home at 70 degrees and you have a 65% relative humidity? Well, for one thing the dew point has jumped up to 57 degrees which we have already noted is the same as the window temperature. For another thing, anyone with 65% relative humidity in a home at 70 degrees has way too much moisture in their air and they are in serious need of some sort of ventilation system  or at least several good exhaust fans! Somewhere back in this post I mentioned that lowering the relative humidity in your home may not help control condensationÂthat is still trueÂIF the relative humidity is lowered because of an increase in temperature. But, lowering the relative humidity by removing water is a different story because in that case you will also be lowering the dew point as you lower the relative humidity and that WILL help to control condensation on your windows. I hope that made sense...please feel free to question anything that I didn't explain well......See MoreLawPaw
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