Bill, the plumber ran the shower at about 3pm yesterday. Even leaving windows open and running the fan for an hour after didn't make the shower bone dry or stop the condensation from coming this morning, 24 hours later. There are always some drops of water in that big shower, I guess! It seems even if I had a stronger fan (mine is around 60-100 cfm), or two fans, I'd have to run them 24/7 and even that might not do the trick. The only thing that keeps the condensation out is going to bed with the shower door opened into the shower (giving room for more air flow). I guess I'm still confused. If the condensation is"normal," why do I need to find a way for it to not happen? Sorry for all the questions!

First I haven't read every post so I may repeat something said earlier. We too have a Venmar 1.8 HRV. Note that there is a difference in operation between an HRV and an ERV. The ERV recycles home moisture back into the home, the HRV does not so it does reduce household moisture. How much flex duct do you have in you installation? Flex duct perfectly installed creats a lot more static pressure than metal ducts. Turns out we have a lot of flex and a flow test on our HRV system showed very low flow levels as a result. I suggest you have your HRV system checked for flow volume; you may be surprised at how little air you are really exhuasting. Some Venmar 1.8 numbers: CSA F326 10cfm per Kitchen Dining room Living room Master bedroom(20) Bedroom #1 Bedroom #2 Bedroom #3 Washroom #1 Washroom #2 Basement (20) Total 120 cfm at high speed ASHRAE Standard 62-2001 Volume of basement Volume of main floor Volume of second floor Total (7,360 ft3) (7,360 ft3) (7,360 ft3) (22,080 ft3) x .35 7,728 ft3/hr ÷ 60 (min/hr) 129 cfm (high speed) Metal Duct capacity (short runs minimum elbows) Duct Diameter Recommended Airflow Maximum Airflow 4âÂÂà40 cfm 60 cfm 5âÂÂà75 cfm 110 cfm 6âÂÂà120 cfm 180 cfm 7âÂÂà185 cfm 270 cfm 8âÂÂà260 cfm 380 cfm Go to venmarces.com and get the manual for your unit. After you have resolved these other issues and you still have the problem try interior or exterior storms. One more point. A parcel of air at 70 degrees and 25%RH will reach 100%RH at 30 degrees. If your indoor RH is at 25% you will have condensation on the first 30 degree surface. I think Rollie mentioned that and it brings other issues into the picture. For instance, air leaking through a wall, think switches and outlets, and hitting a 30 degree surface; that is not good! Go to buildingscience.com for a lot on this subject. Hope this helps! Jim

Hi Tia, I believe I can help. I'm going to throw a lot of statistics at you to address condensation on your windows. Keep in mind that these stats are based on a worst-case scenario of 0 outside and 70° inside, which sounds like it may apply to your climate but is not applicable to warmer, southern climates. Now for some stats. If a window is clear double glazed insulating glass (doesn't matter if it's wood or vinyl), the center-of-glass roomside temperature would be about 44-45°F. (Incidentally, single pane windows with a storm window would be about the same) Adding a Low E coating to the glass bumps it up to about 52°F, and Low E insulating glass with Argon gas raises the glass temperature to 57-58°F. Not bad for 0° outside. You didn't mention if your windows are Low E; hopefully they have and that they have the argon gas as well. However, with insulating glass the edge-of-glass temperatures are much lower than center-of-glass. The type of spacer that separates the panes of glass greatly affects the edge temperature, and much could be said about the merits of different types of spacers. Naturally, condensation, and even ice, would normally occur at the edge first, since that's the cold "weak spot." Clear IG with an aluminum spacer has an edge temp of only about 29°F. Low E glass with an aluminum spacer only raises it to about 32°. Then there are "warm edge" spacers, which are warmer and provide more condensation resistance. Stainless steel spacers are about 37° edge temp on a Low E/argon unit, and Superspacer and TPS spacers would be at the top at about 39°. Again, warm edge spacers typically range from 35-39°, but still tend to max out usually in the upper 30°s. So it's normal for windows to be colder on the edge than they are in the center. Now for the fun part. If you cover a Low E/Argon gas unit with some type of roomside window treatment such as a shade, blind, etc., the center-of-glass temperature drops from about 57° to only 36°. That's an amazing 21° drop. I don't have any exact stats on what that does to the edge temperature, but I would imagine it must drop 5-15° as well. The reason it drops is because the air in the room is no longer freely circulating against the glass. Even a couch or desk in front of a window (or door) will significantly reduce the glass temperature if the furniture is partially blocking part of the window. You mentioned the condensation you're experiencing tends to lessen or dry up by noon. That's classic. Cold/condensation caused (in part) by the shades being down at night, condensation showing when you finally open the shades in the morning, but drying up or reduced by mid-day because the windows now have circulation against them. Enough stats. Condensation, and worse yet, ice, can NOT occur unless two conditions are present at the same time: high humidity and cold temperatures. The cold temperatures on your windows could be due in part to missing or defective weatherstrip, poorly-fitting windows, faulty installation, or just because of cold winter weather. If you have cold weather but low humidity in the house, condensation can not occur. Both conditions have to be there. If you're experiencing condensation on your windows, you have too much humidity given the current outside temperature with the existing glass system that is in the home (assuming that the windows are properly installed and not defective in some way). There are TWO basic solutions: raise the glass temperature or lower the humidity. That's it in a nutshell - those two things. More about those in a bit. First, I'd buy a digital hygrometer from Home Depot, Radioshack, a hardware store, etc. to measure the amount of humidity in the house (about $10-$29). You need to know that. Then I'd contact the manufacturer if possible or visit a window company's website for recommended humidity levels for various outdoor temperatures. Most window manufacturers have brochures on condensation and recommended humidity levels. They usually will state that when it's 0 degrees outside your humidity level inside should be in the 20-25% range. I'm guessing your humidity level is higher than that. New homes are more airtight, and because they are not as drafty as older homes, the humidity is somewhat trapped in the home instead of exchanging with the dry air outside. Also, new homes have more humidity because they are new - the floors, walls, lumber, etc. have a higher moisture content and will take several years to dry out if it has a way of escaping. RAISE THE GLASS TEMPERATURE - One possibility is to raise any shades up when it's really cold out. As mentioned before that can increase the glass temperature by an additional 21° or more, but unfortunately that leads to a lack of privacy. A compromise is to open them just slightly, maybe 4" to 8", so that warm air can circulate against the bottom of the glass (the most condensation-prone area) and partially warm the glass unit. For old existing windows, the best solution is often to replace them with modern, energy-efficient windows. But you've already have newer windows and it's evidently still not enough given your humidity levels. For those who replace their windows, it's ideal to replace them with windows that have warm-edge spacers, Low E coatings, and gas fillings in the units to hopefully avoid condensation. If someone really wanted to get the absolute maximum condensation-resistant windows out there, there are windows that are triple glazed that have a better performance than what you currently have, but most modern "energy-efficient" windows are made with double glazing and that's usually all that is needed. An advantage of many triple glazing systems is that one can have higher humidity levels in the home before condensation issues would arise. Some even have between-glass shades to avoid temperature drops when closed for privacy. Other ways to raise the glass temperature include taking out roomside casement screens during the winter, using free standing fans or ceiling fans to better circulate air against the glass, and adding another layer of glass or plastic (I hate to see that though - it shouldn't be necessary). LOWER THE HUMIDITY - One of the best solutions for an airtight home is to have an air-to-air heat exchange ventilator installed to the furnace. It's required by code for new homes in some areas. It brings in the DRY fresh air from the outside and exhausts the stale HUMID air - giving you healthy air to breathe and lowering the humidity to the desired level. New homes are built so much more airtight than older homes, so they often need mechanical help to get air exchanges. Older homes exchanged air by being drafty. Dehumidifiers will help too, but are generally not as effective, since they usually can't get the humidity low enough. Great for basements though. Simply turning down your April Air humidifier probably won't do it - that simply means the humidifier won't turn on, but it won't remove humidity like DEhumidifiers are designed to do. Other ways include running exhaust fans when showering (and leave them on for a while), or simply stop bathing ;-) In summary, condensation on windows can and will occur under the proper conditions. Even ice can form if the humidity is high enough, the temperature is low enough, and other factors are in place such as restricted airflow to the glass because of window shades. You need a humidity-measuring device to see if your humidity is too high. You need a humidity guide to suggest proper humidity levels. And ultimately somebody has to address raising the glass temperature or lowering the humidity.

It is very likely that you have collapsed glass. Many window companies have/had this problem. Andersen has a repair procedure and the warranty on your windows ends this year. One way to tell is to open a sash. Place an index finger on either side of the glass, opposite one another. Move from the edge to the middle. If your fingers seem to get closer in the middle, the glass is collapsed. This is where the argon has leaked out, but the ambient air is unable to get in, creating a vacuum.....collapsing the glass. Call Andersen @ 1-888-888-7020. Give them the visible glass size of the sash and the date code in the corner. The service includes opening the seal and letting a bit of air in which makes the glass thickness uniform. If this is the issue, no more condensation....unless the humidity is too high in your home.