I know this is a bit of a silly question, but then again if you don't ask
you will never know.
My girlfriend and I are having a discussion as to the placing of a
I say an outside wall, she said an inside wall.
Any advice will be appreciated.
There is no difference between the air pressure inside or outside the
home. The only time it will change and only for a second is when you
slam a door or open a door quickly creating a vacuum or high pressure
If you are in a building - like the Empire State building - and go up
the elevator with a barometer. It will read lower as you go up because
it is always measuring the weight of the air in the atmosphere "above"
its location. A barometer can be used as an altimeter if it is
calibrated for feet instead of air pressure in inches of mercury.
Barometer are one of the best instruments for predicting the weather. If
AP rises - the weather will be dryer and nicer. If the AP falls - you
are going to have wetter and worse weather. If it goes down super fast -
watch out for tornado or hurricane :-)
Of course you "need" a barometer. Put in a place where you have good
light to read it.
Or when you've got a whole-house fan that's seriously oversized.
Or if you've designed your house as a NBC shelter and are
deliberately producing overpressure through your filtration
system. Of course, that's about which SIDE of the
outside wall it should be on, not which wall.
But in any case, the barometer should be placed on the
same wall as the thermometer and humidistat,
which generally means on an outside wall next to
the window, but out of direct sunlight.
Depends on what you are trying to accomplish.
Do you want to accurately read the pressure? In that case, it's irrelevant.
Do you want the barometer to be in a more stable temperature environment?
Then inside wall.
If the barometer reads significantly different inside and outside, then
you are in or close to serious doo-doo!
A truly properly placed barometer is in an outdoor shelter of such
design to have its internal pressure match the pressure of the atmosphere
outside it regardless of windspeed.
If the barometer is in a room with a window and it does not change as a
result of opening and closing the window, then the barometer is probably
reading the outside pressure accurately. Definitely if opening/closing
windows on other sides of the house also do not change the reading.
If the barometer reading falls fast enough to see it moving downwards or
it drops more than about .06 "inch" within half an hour, then there is a
good chance your main worry is not the barometer.
- Don Klipstein ( firstname.lastname@example.org)
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