Window condensation

[David C. Macy]

I had new windows installed about 3 weeks ago and I wanted to ask your opinions on the condensation I have been seeing.

This is my home.

Heat and air off.
Weather has been wet, damp.

Last night about 55, clear. No rain for 2 days , but extremely wet grounds.

east face windows have heavy condensation on the exterior.

Why? Why only the east face?

Thanks for your opinions.

I have called the salesman, installer and window company but they seem clueless.

My dog is really upset as she can not see out her window

[Linas Dapkus]

The dew point is lower than the glass temperature.

[David C. Macy]

Originally Posted by ldapkus1

The dew point is lower than the glass temperature.

Why only the east face windows?

[Linas Dapkus]

Maybe the other windows have more air movement over the surface as they cool. Do the other windows have trees nearby? Trees may block east facing windows cold night sky radiation so they don't cool below dew point.

[David C. Macy]

Originally Posted by ldapkus1

Maybe the other windows have more air movement over the surface as they cool. Do the other windows have trees nearby? Trees may block east facing windows cold night sky radiation so they don't cool below dew point.

The other windows are smaller and all are able to open so there would be slight air movement.

The largest window with condensation is fixed so no air movement. The other large window is also fixed.

Thanks Linus.

[Linas Dapkus]

Prevailing winds in your area have been from the S-SW during the last 24 hours. Humidity has been high (in the 80% range) dewpoints in the 50's. All good conditions for condensation to form on your east facing windows. Call your window salesman and educate him.

[David A. Andersen]

I have the same thing on one of my upper east facing windows in my office.

Linas is correct.

#1 Condensation is relative to the temperature of an object subjected to outdoor ambient conditions above the dew point temp of the object that is getting wet.

#2 Why is it one and not others?: When you begin to "think thermally" as Linas is, there are many conditions not obvious to you that can drop the windows temperature colder than the outdoor air.

Why does frost occur when the temperature is not below freezing?

Why does one side of your truck windows frost and not the others?

Look in your first pic.
See the reflection?
That is a hint.

Now, the windows "perspective" may not be the same as yours. So even if other windows can "see" the sky, it may not be the same.

Why the East side?
That is where the sun comes up.
Heat drives moisture.
Solar convection.

You can not see or feel this stuff.
But it can be measured.
Those that think they can find stuff without Thermal Imaging can chime in now with their undocumented opinion.

When you changed your windows to a better thermal rating, it allowed the window be colder than your old ones and now you see proof that the new are better than the old.

[David C. Macy]

Appreciate the feedback and knowledge.

How would your IR camera find or detect this situation now when condensation is gone and temps are mid 60's and not humid?

Have had windows 3/4 weeks and only have had condensation 3 days in morning on east face windows.

[Robert W. Jude]

how about the location of your heat registers and direction of flow inside? its all relevant.

[David A. Andersen]

Comparison. Very accurate camera correction is required.

To predict when the condensation will form then you must also understand psychrometrics.

Depending upon the amount of latent heat in the outdoor air, will determine if or when it will happen.

Robert, yes that is relevant however please explain when the exact same condition exists at different Windows with different orientations as well as locations are significantly different and the moisture only forms on certain Windows.

Why does frost form on one side window of your truck and not on the other in the wintertime? It's not about interior airflow then.

This time of the year David may not even have his heat on yet. That's when the anomaly usually occurs…

[Robert W. Jude]

residue on inside of my truck windows i would guess.

[Linas Dapkus]

Here's an similar condition explained in simple terms.

[David C. Macy]

Originally Posted by rjude

how about the location of your heat registers and direction of flow inside? its all relevant.

Heat and air have been off on the days the windows condensate.