I recently discovered mold on the lower frame rail of five windows in our home. I hadn't noticed this mold until I was washing windows one day late last month [April].
These are Pella Designer Series Casement windows that allow a mini blind to be in between the main dual paned glass and an inner third pane of glass. Neat idea and one of the reasons I picked them to be in our new home as well as the quality of Pella windows. You can read all about the building of our home by doing a search on Sawmill Creek" under "A New House".
I was purchasing blinds for installation in four of the eleven windows that did not already have them, so I emailed the sales rep with pictures to see if the person they were sending could look at these windows. The reply was to show the tech the windows and the pictures I had sent were shared with the sales reps manager as well as the service dept.
During the two week period between the email and the arrival of the tech on May 10th, I was trying to figure out what could be causing this problem. I did have a humidifier installed on the HVAC system and was given instructions about setting the humidity level by the HVAC contractor. I was to observe the windows on a regular basis and if I noticed any condensation I was to lower the setting on the humidifier to dry up the air in the house. I checked at least once a week, if not more often, and the only windows that were showing any condensation were the bathroom windows after someone had taken a shower, so having this mold was puzzling in my mind.
During this two week period I have deduced that the mold on these windows, while not of the same intensity on each window, is more prevelent at the side where the crank handle and underlying hinge is located. Perhaps the windows are not sealing properly there and this is what is causing the mold. It is also strange that two of the windows are above heating vents, while the other three are not. One of the windows over a vent has the most mold while the other over a vent has a small to medium amount of mold. Two windows face south, one window faces north, one faces west and one faces east. One of the windows not over a vent has the second most amount of mold. There doesn't seem to be any other factor to tie the mold on the various windows together, except an air leak at the crank/hinge area.
May 10th arrives and the tech shows up at 7:30 AM with the blinds in hand and asks what else I have for him to look at. I show him the sliding door and then the mold on the living room window, which is one of the ones he will be installing the blind in. I explain that I have five windows with varying degrees of mold growing on them. One of his questions is if the mold is new? I explain that I just discovered it and I'm guessing it didn't grow overnight. One of his next questions was what the humidity is in the house. I explain that I have a humidifier and I think the unit is set at about 40-50%. I later found that it was set between 35 and 40% humidity and again I had no condensation during the winter months on any of the windows.
Disconnect the humidifier was his response. That was causing the mold because of high humidity during the winter months. The higher humidity is trying to get to the lower humidity outside which causes condensation and consequently the mold on my window frames. My response was disconnecting the humidifier was not going to happen for various reasons which I didn't go into.
My common sense understands what he is telling me, but the same common sense says that if that's the case then why don't all my windows have mold? I explain what I said above about the heating vents and that the windows are facing different directions and the only common bond I can see is the fact that the mold is heaviest near the crank/hinge. He has no answer except that it's all caused by humidity and don't use the humidifier any more. I lost my cool at this point as he wasn't going to even investigate if there could be a problem with the windows. I demanded a call from the sales rep or his boss to further discuss this matter. He went on with his work and I was pleasent for the remainder of the time he was here. He also left me a gas company report on heating and mold in new air tight homes. Very informative, but little I didn't already know.
A couple of hours after he left I got a call from his boss, the manager of the service dept. The conversation began cordially until the manager said turn off the humidifier and that was the cause of all my problems. Not, well maybe there is something else going on here that we should check. I personally don't know of any manufacturer of any product that doesn't have some defects from time to time. I guess, at least from this service managers perspective, Pella is perfect and their windows don't ever have any defects.
So here I am trying to decide if I'm totally out in left field and what my next move might be. I have thought about calling in one of those services that can find air leaks by putting a vacuum to the house.
I am going to write to Pella, but I thought I'd get some opinions from the vast knowledge bank here and at the "Creek" before I make a total "you know what" of myself.
Thanks for taking the time to read this rant and I look forward to any and all views on the subject.