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Andersen DH windows getting condensation on the bottom inch of the top pane


kisonay's Avatar
Member

Join Date: May 2011
Posts: 12
NY

01-03-14, 06:02 PM   #1  
Andersen DH windows getting condensation on the bottom inch of the top pane

I had 10 new Andersen Double Hung 400 Series windows installed in May of this past year. I noticed a huge change in the insulation factor over the summer. It took a lot less energy to keep the house cool.

Now I am in the Northeast and it is currently 13˚ F outside. I noticed today that on all of my windows (all 10) that on the top pane, the bottom inch or so is sweating/fogging. Now this is on the interior of the window and not between the two panes of glass.

I came across this wonderful post here which does an amazing job explaining what causes it.

We keep the house at about 67˚ and the relative humidity is 40-45%.

My question is, why would it only happen on the top pane of the double hung window and why only the bottom inch or so of the window and not the whole pane? I would think if the glass was hitting the dewpoint that the entire pane would fog.

An image of the sweating can be seen at View image: IMG 0924

Appreciated the feedback and insight in advance.

 
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kisonay's Avatar
Member

Join Date: May 2011
Posts: 12
NY

01-03-14, 06:05 PM   #2  
Andersen DH windows getting condensation on the bottom inch of the top pane

I had 10 new Andersen Double Hung 400 Series windows installed in May of this past year. I noticed a huge change in the insulation factor over the summer. It took a lot less energy to keep the house cool.

Now I am in the Northeast and it is currently 13˚ F outside. I noticed today that on all of my windows (all 10) that on the top pane, the bottom inch or so is sweating/fogging. Now this is on the interior of the window and not between the two panes of glass.

I came across this wonderful post here which does an amazing job explaining what causes it.

We keep the house at about 67˚ and the relative humidity is 40-45%.

My question is, why would it only happen on the top pane of the double hung window and why only the bottom inch or so of the window and not the whole pane? I would think if the glass was hitting the dew-point that the entire pane would fog.

An image of the sweating is attached.

Appreciated the feedback and insight in advance.

Attached Images
     
 
lawrosa's Avatar
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Join Date: Dec 2010
Posts: 17,607
NJ

01-03-14, 07:09 PM   #3  
Threads merged.....................



Mine do that too... I did not read that other thread but you need to lock the windows with the latch... It pulls the seal in tight...

Just my opinion....


Mike NJ




"The problems that exist in the world today cannot be solved by the level of thinking that created them".


- Albert Einstein




Last edited by lawrosa; 01-03-14 at 08:01 PM.
 
XSleeper's Avatar
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Join Date: Dec 2004
Posts: 19,342
NE

01-03-14, 08:09 PM   #4  
That's pretty normal when the temp outside is that low and your humidity is that high.

It's only on the bottom because of 2 things. Cold air falls, so the glass is getting "air conditioned" as the cold air from the rest of the pane drops. It also occurs on the bottom of the sash because of the shape of the window. Any ledge will block warm air that may be rising, and it "skips" that part of the sash, creating a cold spot on the frame.

The edge of the glass will always be the coldest, since it's in contact with the metallic spacer you will get heat transferring from one side to the other. The center of the glass is always the warmest.

 
kisonay's Avatar
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Join Date: May 2011
Posts: 12
NY

01-05-14, 04:29 AM   #5  
Appreciate your responses. I figured it was ok since it wasn't the whole panes and made sense that the bottom would be colder.

It was defiantly was due to the humidity. I was able to drop it to 35% and it was colder last night then the night before and I had no condensation.

 
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