For a more scientific explanation, pressure falls with altitude because there's less air compressing it from above. The reduction in pressure is equal to the weight of the air below, because it's no longer above you pressing down. Because cold air is denser than warm air, if you rise say a meter in altitude, the reduction in pressure will be greater in cold air because the meter thick slab weighs more than the warm air slab. This means that air pressure falls *faster in cold air,* and *slower in warm air.* This means that if it's cold outside, but warm in your house, the air pressure at the top of the house must be higher than outside, and the air pressure at the bottom must be lower, so that the average air pressure is overall equal to outside. So the average pressure is equal, but the pressure at the top and bottom of the house is different.
So if you had a wood stove in the basement how could you easily adjust for stack effect issues. Would opening a window or door on basement or all floors help?
I have watched and enjoyed many of your videos - just a building science keener myself. But you made a rookie mistake when you attempted to show that you can measure stack effect from totally inside the building. You weren't measuring the pressure differences at the ends of the tubes - that's not how it works. The air inside the tubing is changing in density the same as the air outside of the tubing so the net result is that you could remove both tubes from your manometer and get the same reading - except you had the one tube under the basement door. You were measuring the pressure in the basement across the door. You had closed the door I noticed. If you would have turned the HVAC off your gauge would have went to zero. Probably the HVAC had more returns than supply in the basement and that is what you were measuring. Still love your videos - lets all keep learning together.
an ad that actually explained things in a real way. nice
Thanks again Larry you explain so the average person who cares to listen can understand such simple building principles.
For a more scientific explanation, pressure falls with altitude because there's less air compressing it from above. The reduction in pressure is equal to the weight of the air below, because it's no longer above you pressing down. Because cold air is denser than warm air, if you rise say a meter in altitude, the reduction in pressure will be greater in cold air because the meter thick slab weighs more than the warm air slab. This means that air pressure falls *faster in cold air,* and *slower in warm air.*
This means that if it's cold outside, but warm in your house, the air pressure at the top of the house must be higher than outside, and the air pressure at the bottom must be lower, so that the average air pressure is overall equal to outside. So the average pressure is equal, but the pressure at the top and bottom of the house is different.
Where is the top of the door casings?!!
Good video. That Christmas tree was distracting in it's awesomeness.
Great explanation ! You are never too old to learn
So if you had a wood stove in the basement how could you easily adjust for stack effect issues. Would opening a window or door on basement or all floors help?
Nice Larry!
I would like to say thanks for a great video.
Awesome video.
great video
That was useful information.
Good video
Well explained. 🌠🌠🌠
I have watched and enjoyed many of your videos - just a building science keener myself. But you made a rookie mistake when you attempted to show that you can measure stack effect from totally inside the building. You weren't measuring the pressure differences at the ends of the tubes - that's not how it works. The air inside the tubing is changing in density the same as the air outside of the tubing so the net result is that you could remove both tubes from your manometer and get the same reading - except you had the one tube under the basement door. You were measuring the pressure in the basement across the door. You had closed the door I noticed. If you would have turned the HVAC off your gauge would have went to zero. Probably the HVAC had more returns than supply in the basement and that is what you were measuring. Still love your videos - lets all keep learning together.
*hmmmmmm*
I told my white friend, "That's awfully white of you." He then had a racist facial expression.