How do I prevent condensation on my balcony windows?


On the street, temperatures at night are about -5 °ะก and about 8 °C during the day. In the apartment it is about 25 °C. So, there is condensation on the windows and I don’t want to wipe the windows every time.

How do I prevent condensation on the balcony windows?

Do Silent Condensate Pumps for Air Conditioners exist?


I need to install a Condensate Pump in a new A/C in a bedroom, and there is no choice but to pump the condensate up to a drain on the roof.

The A/C technicians have told me about different types of condensate pumps, but they all seem to make an audible sound on regular basis when the pumping action kicks in, and even though the pumps would be on the outside of the wall of the bedroom, they will be right next to a window that will be next to a bed, so my fear is that the regular sound of the pump will be just loud enough to drive me insane as I wait for the next pumping round to kick in, and the next, and the next…

So I was wondering if there are any silent condensate pumps on the market that are also reliable and that will last for years without requiring maintenance.

Any ideas?

Should I insulate the exterior foundation wall above grade or insulate the interior basement wall?


An existing basement wall is not insulated on either side. Humidity inside is causing significant sweating on the cold wall in the winter months. Outside, the top 4 feet of wall are exposed above the ground. I am less interested in insulating for energy savings and more interested in avoiding the condensation problem as the basement space is actually a garage. Will I solve the condensation problem by insulating only the outside wall to a depth of about 2 feet below grade. If not, then what is the best way to insulate the inside with a proper vapour barrier to isolate the humid air from the cold wall?

How to protect lens from mist formation while shooting in places like beaches?


Usually when photographing cool breezy areas like beaches in the evening, I have experienced mist formation inside the lens. Once this mist formed, it stays there for at least an hour even after keeping the camera inside the bag.

How to protect the lens from these kind of mist formation? Is this really harmful for the lens?

Also what are the safe ways to get rid of the formed mist quickly?

Why am I having an attic ventilation problem this year when I didn't last year?


This winter in the attic I noticed ice on the roofing nails. Obviously warm moist air condensed and then froze on the cold nails. When the weather broke and warmed up a bit, I was back up in the attic and noticed black mold on certain areas of the lower attic ceiling going toward the eaves.

Some interesting facts:

  • I have been in the house two years and did not notice this happening last year.
  • This is only occurring on one side of the attic ceiling, the other side is completely fine (no rusted nails poking through, no mold)
  • I recently put down some more plywood so I can have more area for storage, and before I did that I added some more insulation to the attic floor (rolls). I wonder if that has anything to do with it?
  • It was also a colder drier winter this year so we had humidifiers in use more, so that may also have something to do with it.

I am just curious why it is happening this year and not last year, and why on only one side of attic ceiling (roof).

Important Information:

  • For ventilation of the attic we have only two gable vents (one on each side of the house), about 1.5ft x 2ft rectangle each. These do not have any fans.
  • There are no soffit vents or ridge or roof vents; just the 2 gable vents.
  • Looking at the lower part of where the attic roof slopes down and meets the wall I notice there is a board that blocks the attic area from the soffit area/eave. So if I was to put in soffit vents from outside, I believe I would have to also drill holes from inside attic through this board so the outside air could actually pass into attic and not be trapped in this blocked off area.
  • The attic space is about 600sq ft.
  • The only insulation is in the attic floor and on there walls, there is no insulation on the attic ceiling.
  • Bathroom fans are vented to outside the home (not into the attic or soffit)
  • I live in Massachusetts where winters get cold and summers are hot and humid.

My questions:

  1. What should I do?
  2. Why was the gable venting system in place good enough last year but not this year?
  3. Why only one side of attic affected?

I recently beefed up the insulation and seal on the pull-down attic entrance as this could be an area where warm moist air was entering into the attic (the entrance is on same side as the attic problem area). Will that fix problem, or do you recommend installing more ventillation anyways?

Will a fan on the gable vents do the trick, or do I need to install soffit vents anyway?

Will soffits with the gables work, or will ridge or roof venting also be required?

Thermodynamics: Are pressure and temperature enough to calculate enthalpy?


enter image description here

From the chart above, it looks like it is possible to calculate enthalpy from just pressure and temperature. After a few hours of Googling my question, I’m not able to find anything helpful.

My company is interested in finding the effectiveness of an air conditioning system by measuring the change in enthalpy from one side to the other. As a software person, I need a formula that I can use to calculate the enthalpy. I know this formula would need to include different properties of the gas, can you elaborate on what those constants are? Thank you very much.

What to do with a cold corner?


I live in an apartment on the 4th floor. My bedroom has the misfortune of being in the very corner of the building – it has two outer walls. On top of that, the corner between these two walls is facing north (where the sun don’t shine) and there are no obstacles for the cold winds coming from that direction. The only insulation that the building has is about 30cm of concrete.

As a result, the corner tends to be substantially cooler than the rest of the walls and lots of condensation gathers on the wallpaper. Since I cannot do anything to the outside of the building, is there anything I can do on the inside? Some material that I can place beneath the wallpapers? (I have enough spare wallpaper to fix the corner, but not the entire wall)

Can remodeling work around a window cause moisture / condensation problems?


I had flashing repair work done around one of three windows in my bedroom last summer. When it started getting cold, I noticed moisture / condensation on one of my windows. I thought it would go away in a few days; it did not. There is continuous moisture on the main window where the work was done. I’ve been in my home 10 years and have never experienced this problem. And, there is no moisture on the other two windows in my bedroom or on the three windows in my adjoining bathroom. I am wondering if the flashing work could have caused this problem.

Why am I getting condensation on vapour barrier?


I installed some vapour barriers on the windows recently due to it getting a bit cold, but have been noticing that I’ve been getting a fair bit of condensation on the inside facing part of the plastic. Now the temperature has gone down about thirty degrees since I installed these, so I’m wondering if it’s just not up to the task, or I’ve installed them improperly/poorly, or maybe something else that I’ve missed? Here’s a picture of one installation. as you can see there’s condensation on the lower part of the window.

window with condensation on the plastic vapour barrier

How can I interpret negative values of potential evapotranspiration?


If I extract Potential Evaporation (PET, W/m$^2$) from the National Centers for Environmental Prediction (NCEP), climate reanalysis data (downloadable as netCDF files here), there are some negative values, e.g. for summer in southern Manitoba (50N, 100W), I get the attached distribution of PET values.:

enter image description here

Is this a real physical process, such as condensation (dew formation), or is it an error (e.g. should I average over these values or set them to zero)?


update requested metadata:

The metadata (contained in the files) says that the valid range is -800, 5200; here is further description of the ‘pevpr’ variable (provided in the data header):

  • long_name = “Monthly Mean of Potential Evaporation Rate”
  • valid_range = -800,5200 ;
  • units = “W/m^2″ ;
  • add_offset = 0 ;
  • scale_factor = 1 ;
  • missing_value = -9.96921e+36 ;
  • precision = 1 ;
  • least_significant_digit = 0 ;
  • var_desc = “Potential Evaporation Rate” ;
  • dataset = “CDC Derived NCEP Reanalysis Products” ;
  • level_desc = “Surface” ;
  • statistic = “Mean” ;
  • parent_stat = “Individual Obs” ;
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