How to circulate air in a house with fans
Best fan placement to move air through the house
Timecodes:
there's a very visible step function
and again a clear step and wind speed
when i move the fan
now at one and a half meters i'm
actually getting
the best readings yet i want to measure
where's the best place to put one of
these fans
to circulate air through the house
and i'll close the doors to the rest of
the basement
i've got another window facing the same
way
and i'm going to use an anemometer to
measure how much airflow i'm actually
getting through the house with that
first test is blowing air into the house
full power i was trying to pull air
through that window and let's see how
the anemometer is doing
nothing let's flip that fan around
and try blowing air out the window
and this thing is spinning very very
slowly and the problem is
this thing is very deficient at
displaying very low
speeds so i wired the sensor in this
thing
to a raspberry pi and that can actually
give me a much better readings than this
device itself at low speeds
and it graphs it on the screen too so
now i have this in the same room as the
fan
with a long wire going over to my
anemometer so i don't even have to come
in here to check it
let's turn the fan on blowing air out
the window
and we're starting to get more
consistent readings here
we're getting uh about .18
come on somewhere around 0.2
0.4 meters per second i think i need to
average this over a longer period of
time unfortunately i'm seeing
a bit of wind outside
and that's making my numbers kind of
move all over the place
okay averaging over about a minute i get
a quarter meter per second now let's see
what happens if i move the fan
a little bit further away from the
window and
a little bit of windiness outside is
causing some variations
but i think it's averaging quite a bit
higher
so i just tried it for a while without
the fan running and just a breeze caused
some wind now i got turned back on at
1.2 meters away from the window
and it's clearly having an effect it's
just getting gustier outside messing up
all my readings
i ended up taking lots of readings and i
graphed those
and nothing's really clear other than
with the fan further away i get more
airflow
it's the next morning and the weather is
calm so let's try again
i got my fan right up against the screen
and the anemometer is turning slowly
but consistently and i do have a little
bit of bumpiness but
nowhere near what i had yesterday
and for moving it back there's a very
visible step function
for the wind speed
and again a clear step in wind speed
when i move the fan
i love getting clean data very
satisfying seeing this thing go round
and round
smoothly even though i don't actually
have to look at it
with the fan this far from the window i
do have to be careful about getting the
aim
just right now at one and a half meters
or five feet from the window
i'm actually getting the best readings
yet
just a little bit higher than before i
end up going back and forth in terms of
distance just so i wouldn't be
biased by time and then graphing it as a
function of distance
the airspeed increased as i got further
away up until
bit past 50 centimeters or about two
feet
beyond that it stayed pretty much the
same even when i went as far
as 2.1 meters or seven feet the speed
didn't drop very much
so at least for this window and this fan
optimal placement is probably about two
feet there's no need to go any further
than that
and now testing with a box fan straight
up against the window screen and the
wind speed
doesn't appear to be that much higher
than it was with a fan
and i tested again with it further away
from the window and further and then
closer again
just moving that fan closer to the
screen again you can really see a step
down in wind speed
this is all somewhat counter-intuitive
but the reason is the fan is throwing
air out the middle of it
but towards the edges it's actually
sucking in the air from the front
so if that fan is straight up against
the screen it's sucking in
outside here and graphing the box fan
here is right against the window
and this is 20 and 30 centimeters away
from it so
more air speed and then this would be 90
centimeters
about three feet so clearly up against
the window is
less good than further away i really
meant to get more readings
but then this happened
this experiment is done way out of
balance now
but is one of these oscillating fans
really completely ineffective at pulling
air through the window
let's put it right in right up against
the screen
and that doesn't make enough wind to
even move the anemometer
and that seems counterintuitive but if
you stand behind the fan like that
you really don't feel any wind just in
front of it
and the fan is just pulling in air from
all sides
so why should it pull the air
particularly from behind which is why a
fan like that is particularly
ineffective at pulling air in from a
window
and my takeaway from all this is it's
always better to blow air out the window
than trying to suck it in and move that
fan away from the window
at least half a meter or two feet
but if there's even a light breeze
outside you're much better off just
opening all the windows because that'll
completely swamp out
what your fan can do and the surprise
conclusion from all this
is that this desk fan about three feet
from the window will move as much air
as this box fan in the window even
though the box fan is much larger
of course the box fan would do better if
it's away from the window too
Related queries:
how to circulate air with fans
should i circulate air in house
how do i circulate the air in my house
how to circulate air in house
