0:02 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
0:49 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
1:36 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
2:22 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
3:08 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
3:54 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
4:40 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
5:27 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
6:12 though the box fan is much larger of course the box fan would do better if it's away from the window too
