Air flow: It's all about fan thrust
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- Опубліковано 28 вер 2024
- Testing how much air the fans can move through a window. This turns out to be considerably more than the air that goes through the fan itself, even if the flow is impeded by a bug screen.
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It would be interesting to plot the air moved and noise generated to get a "noise efficiency" rating for the fans.
This. We have a very powerful fan at home, I think it's 3000W. But we almost never use it, both because it's very heavy and very loud.
My in-laws happen to have a very very silent fan and I'm very envious!
The sound signature can be more important than just pure noise levels
It would be interesting to see if the noise efficiency remains consistent across all fan speeds.
Also, without a testing body, any of these ratings can't be compared across brands.
I'm curious what that 3,000W fan gets plugged in to.
@@fantabuloussnuffaluffagus just a wall plug. European outlets can deliver 16A @ 230V. So approximately 3600W. In reality most appliances are limited to 3000W because there's multiple outlets on one breaker
Excellent video as per usual, but I'm somewhat surprised you didn't test one of your home made blowers in the test rig as well. Would be rather interesting to see where your trash picked plywood and yard-sale motor creations compare to one another, let alone the store bought competition. Thanks again for sharing.
Those blowers were mostly meant for dust collectors, rather than air movers.
His box fan might as well be trash picked :D
@@user2C47 True, originally i had thought to ask for a performance test vs one of those stationary squirrel cage fans, or for a comparison of velocity optimized vs static pressure optimized fans. But then i remembered that our gracious host both has kids, a million other things to do, and isn't like Project Farm and willing to buy fans just to test for us. I blame lack of sleep on my part.
disappointed not to see the garden blower...
I picked up one of those Dreo fans, they are very impressive. One of my favorite (albeit mundane) features is that the LED display will automatically turn off depending on ambient lighting conditions, i.e. when sleeping
The pedestal one?
@@pengting87 Nah the small desktop silver one - though I imagine the pedestal one does the same thing
The videos on this channel over the past several months are my favourite content on youtube right now. Thanks Matthias.
I’m a big fan of your experiments, the results blew me away.
Yeah, these videos really catch the wind in my sail.
They have a cool(ing) effect
I see what you did there being a "big fan" 😅
@@rhranjithkumar34”blew me away”
Go to your room Adam Earl.
I would have liked to see the watts power input to each fan on your graphs. Also as you move the fan backwards in the room you are creating all kinds of air patterns that can effect your sensor . For example if air is going out the back door it will make different readings on that . A smoke test would be interesting see what the air is really doing. Also a blower door test where the entire door is blocked so you see how much positive or negative pressure is created.
Agreed, cfm per watt would show the efficiency of each fan.
Yep, seems like a miss. Based on listed specs only, Vornado is 44W and Dreo is 48W, which seems to account for the difference between the two outputs.
@@brjan. if you watch Matthias' video comparing the two from 3 weeks ago, it seems the dreo is actually more efficient than the vornado. idk about the rated power but his measurements show 53 and 38W at full power for the vornado and dreo, respectively.
Agree with the power input graph... but the negative pressure measurement would not yield any result... Assuming the house as a closed system... the volume is just too big...
He doesn’t have an actual LAB… although pretty darn close!
About 2 weeks ago I bought a 106cm Dreo tower-fan, because of your videos, and I'm very pleased with it. Quiet and blows more air on lowest setting than my 46cm honeywell classic ventilator on medium setting. And on highest setting, it's like putting your head out of the window while driving your car.
Greetings from Germany, the country with this awesome window-mechanics 😉
Where did you get it? I can't seem to find european distributors
@@flyingvish I bought it on Amazon
Just bought my second Dreo DC Desk fan. It's a terrific little machine.
Thanks Matthias. Learned several things from you! Also enjoyed the end “Thruster”!!
Can’t thank you enough for the original video. Bought one and have never been so happy with a fan
Since we’re here, I just wanna say I feel like MOST if not all Lasko’s move air really good. It feels strong, fresh & they do a good job. They’re also cheap & have lines that are higher price, they have lots of options… just wonder if anyone else has experienced the same?
This really is a GREAT sponsored video- and your research and testing are remarkable sellers. I've been a big fan of Vornado for years and have many of them. In general, they work very well and can be very quiet. But the Dreo's performance looks exceptional. I think I'll pick up one of these!
Maybe Vornado has cheapened their manufacturing…
I just bought a Vornado at Costco, not on a short neck, but in a square form on TV-like feet, it can point low or upwards. It REALLY moves air, but is so noisy and rattling you can’t hear yourself think.
It was only around $40 dollars though.
Think I will take it back and apply the $$ towards a Dreo.
@@k.hendrickson8735 I actually DID buy the Dreo- specifically the pedestal one. Quite frankly, it’s the coolest fan I’ve ever owned. It’s extremely quiet and that silly feature of the app allowing you to point it where you want, remotely, is actually really useful. I typically keep it on a combined horizontal and vertical oscillation, but when I’m feeling hot I can open the app and position it on me. You can also tweak the oscillation range horizontally and vertically to specific angles of rotation. I don’t recall this being mentioned on the video, but there’s also a feature called “natural” mode in which the fan randomly speeds up or slows down in order to simulate wind gusts. It’s the craziest thing I’ve ever seen in a fan, and I quite like it; it’s like being outside while inside. In short (I guess not really) I would absolutely buy it again and don’t in any way regret my decision to do so.
If you get the Lasko fan with the round plastic pivoting frame you get exactly the same motor and blades as the box fan. The round frame is only about a tenth as loud and moves a lot more air than the box version, though.
Very interesting stuff! Perhaps you could test the effect of removing the fans' protection grilles in terms of both thrust and noise?
For shrouded fans i'd imagine they'd move a little less air. Non shrouded ones might see an increase
For the air circulator fans, the grille acts as a stator against the rotor of the blades, and is actually necessary to collect the airflow into a focused jet
😯 Who knew??
Thank goodness you scienc-y types do what you do!
Love these type of videos. Very informative. Thank you and keep up the good work.
Making a video and then contacting the winning company if they want to sponsor is a great business model :D
Thank you for these. I bought the pedestal one and it's great. The app is surprisingly good too. I'm getting the other one soon. I know you tested with 12V but I'm sure you can also use a 20V USB-PD trigger to run it at 20V, and then you can use any USB-PD 60W adapter or even some power banks.
Are you getting the dreao desk fan next ? It’s interesting that it is more powerful than the pedestal version
@@bunit8 I'm not entirely sure I'm getting it, I do think I'd prefer it with a pedestal cause I have no use for a desk fan. I was wondering if I could take off the base like on the pedestal model, and attach it to a stand but now I see that it has electronics in the base, unlike the pedestal model.
I do see that they have different blade configurations, 5-blade vs 3 blade. I don't know if it makes any difference, but the blades on the pedestal one have this golf-ball texture to it, more like a curiosity, don't think it would make much of a difference in noise or air movement.
wow, I'm impressed yet again
Woah! I can buy 3 box fans at the farm store for the price of one Dreo Desk fan. Which I have one of that has been running 24/7 for 2 1/2 years. I like air circulation. p.s. I think your videos are great! So interesting, well thought out and I love the data gathering!
Thanks Matthias, that's really interesting. Here in Texas our attics get hot. I am monitoring mine and when it is 100 F outside the attic gets well above 130 F. So I was considering getting one of those solar attic fans that sits on the roof. But based on this video, it seems like it would be better to put a fan in the attic and point it at my ridge vent. What do you think?
It would be interesting to see you do a video on attic air circulation by the way!
if yor ridge vent is 2'x2', and the fan is rated for the temperatures then yes. My guess is that neither are the case.
Sounds like a worthwhile experiment….
My big question is: Would an electric fan cool the attic enough to reduce the electricity bill for cooling the home below? 🧐
Or would the power usage needed to run the electric fan in the attic be justified at all?
There are NO fans in the universe rated for the attic of my home in Phoenix in August.
I vote yes for thrust ratings on fan packaging! Something else to make it easier for an apples to apples comparison when fan shopping similar to the simulated "nutrition facts" on light bulb packaging added many years ago. I know I've seen a simple version on ceiling fan boxes in the big box home improvement stores.
couldn't agree more
but that would just make too much sense from a consumer perspective, we couldnt have that!
I love when you embrace the analytical questions in your head, then develop a scientific way to analyze it.
Pure science. Thank you
Thanks for the video. This and a few of your others led me to buy the Dreo.
It’s fantastic (sorry) and outclassed the my Dyson and Vornado by a lot.
I actually trust the brands that let you test their products after you do your things, because MAN you hold no punches in your reviews haha.
Really enjoying your only fan videos, I’d almost pay a subscription for them. 😂
Cool experiment! Now it's interesting to see how thrust will change if you remove all (or at least front) protective grid from fans.
I like when you add in the factor for how much power you're drawing.
I think the thing about the dyson that we often forget is the size of the impeller used in their turbines is _miniscule_ compared to their competitors, and that the fact that it can even push 1/4 of the air of the Dreo is fairly impressive. I don't think it's worth the money at _all_ but from an engineering perspective the dyson's pretty incredible.
An excellent video, clearly explained with a real-world finding of what was a complex and carefully designed expeiment.
Another reason the Vornado and Dreo fans move so much air by themselves is the cylindrical cowling surrounding the blades. if you took your box fan and put four blocks of wood around the blades in a similar and closer radius to the blades you probably would vastly improve the amount of air moved. The king of fans, the centrifugal fans win at being relatively quiet compared to most axial fans with a large amount of air moved.
As someone who doesn't use air conditioning I splurged on the Dreo pedestal because I wanted a quiet fan (instead of the box fan I was using). It's weird to have such a positive opinion on a fan, but I'm really happy with it . And surprisingly all the functions are very useful too. I guess you could say... I'm a Dreo fan-boy now
my main gripe about the pedestal one is that you need the app to turn on "turbo" mode
The consistent results of all of your tests are that the cheap fans do best...crazy.
Thank you for providing us with thrustworthy data.
I like how the arrows on the box point in the direction of the air flow haha.
What a great video. I loved the cart at the end. Cheers
Would love to see more on those window fan types! They seem like a good quiet/compact option, but it's hard to tell if any of them are even good. Literally no real stats available anywhere.
That's why i love your videos. Nice experiments
What about CFM/Watt? Wondering if there's an efficiency gain for one design or another.
Thanks nerd. I love your work.
It's just sad the Dreo isn't available anywhere except America 😢
I'm glad you checked the one blower, but I'm very curious how a normal sized blower fan would compare.
Very interesting! I have a 1953 Robbins & Meyers 22" 1/2 hp full house window fan that has stamped on its data plate that it moves 3400 cfm, and is certified for this volume by Texas A&M University. It draws a massive draft through all the windows of the 3 floor house when turned on, and it has been in continuous operation for 70 years with a bit of oil every season. I would love to send a Dyson fan (and all other Dyson products) through its steel blades, but of course I won't insult it with such marketing hype junk.
😂
You had me at ‘1953’ !
Dreo currently makes no window fans nor any all metal fans of any type. Hopefully one day they will. A fan ought to last a century or more.
Thank you, I really appreciate this analysis. Fantastic job as always!
Great stuff. Can you publish entrained CFM per watt for each fan?
More than I ever wanted to know about fans.
I wish You can test the effectiveness of evaporative cooling to lower the temperature and how to make use of it in the most effective way. Also, a DIY evaporative cooling project by using existing fans will be much appreciated. Because, people tend to be cost conscious after energy price increases.
Dreo can thank you for the 4 fans I have purchased after your first video.
Love how quiet they are and the app is a plus!
Which one is your favorite?
This video definitely blows! Nice work!
I just love this channel, i really do.
Your video was as informative as usual thank you for making it
I have that same vornado but it’s a pedestal variant (model no: 7803), holy crap on high it’s powerful
THAT'S A REAL TEST OF A FAN! But anyway, who needs a fan that noise is like flight in the plane?
I always enjoy your comparison videos. If I had the time and equipment I would do these kind of experiments.
It would be very informative if you retested the box fan after adding a circular shroud inside the box to reduce air recirculation inside the box around the blade tips. Leave about a quarter of an inch (sorry; about 6.35 mm) between the blade tips and the shroud. All the other fans in this comparison do have circular shrouds.
This video broke my brain. I have so many tests to run now. 🤯🤦🏻♂️
So easy and so good. Measuring thrust. At minute 7 in the video.
i am watching this a full year later excited that i might get a deal on the dreo...but alas. also, which dreo desk fan did you test? should i assume it was the 13"? thanks for your great analysis. i am curious but not scientific at all and i learned lots
Coincidentally, I have the same box fan and I've been contemplating making a shroud or circular duct to surround the blade. By having a fairly close fitting shroud the efficiency will be increased over the square box w/rounded corners, therefore I hope to move more air.
that might actually make it worse
What if you make wood inserts for the corners of the box fan to make it "ducted"?
A few years ago you did the experiment of placing the fan at a distance from the widow. These results seem to match.... but weren't you drawing in outside air in that experiment?
yes, I was. But this year is just too rany. Also, by doing it all indoors, I get much more consistent results
man should start a fan channel lol, hes got the collection
So, is it better to blow the hot air out of a warm room, or pull the cool air into a warm room?
always better to blow. If you want to put the fan outside, you could blow the air in too
I am looking to buy a window box fan that can pull some air through my house from open windows in other rooms on the same floor. Do you have a particular brand and model that is very effective at doing this?
I really miss having an attic fan that was very strong and good at creating air flow throughout the house.
Noise level is not important.
Do you have a review for the best long-lasting rechargeable fan?
Should also talk about blade pitch and how that also effects the CFM
My current heuristic is "However many watts a well-designed fan uses is directly proportional to free airflow". Obviously this is suspect with regards to 'well designed', and there will of course be changes associated with higher pressure-curve fans and bigger/smaller fans, but... Watts is a metric you can get insight into without opening the box frequently.
It would be interesting to see a test using this test setup for air filter boxes for
Is there any circumstance where positioning the fan to suck outside air and blow into the house is more advantageous than blowing out?
I find Matthias onlyfans video not only entraining but also useful
it would be nice to see measurements of volume plotted vs cfm, as well as tests of fans like the chinese 9 blade fans, which seem to be quite powerful while much more quiet
This video is awesome! im happy I bought the dreo one!
Do you have any number on what Watt consumpion is using on every speed?
Can you also measure in MPH as well?
We can see that the CFM is pasted in your awesome data sheet that is easy to understand.
Interesting study! So, thrust rules :-)
Cant find the desk fan in the UK , are they sold under any other name
This setup might be making some of these fans more effective.
Can I watch how the air flows in the room by fan? That is airodaynamics of air? Any simulation experiment?
amazing content
Is there a formula for determining the best distance from a window or door based on thrust?
no, but its easy enough to feel how wide the air stream is at any distance just with your hands and face
Turn that fan around on the sled you made for it and you should be able to steer it around the place by turning the fan remotely. 🙂
yes, that would be fun, but panning the fan side to side is too slow considering how fast the cart went. Also, I didn't have any caster wheels on the cart
And the energy used for each ?
thrust +noise rating would be great on the boxes.
some fans like the box one have such bad blade design they make more noise than air.
if you want to be amazed, just buy a 15$ wooden prop for airplane and put it on a pedestal fan without the guards, it move so much air the fan will sometimes fall down on its own. if fans had proper impellers they would be so much better!
i want to see the box fan with a furnace filter on the back.
I just bought a ‘Vornado’ but it’s too LOUD on any setting but 1.
So thrust to price with Dyson vs. Dreo Pedestal, means that for 1 Dreo at $139.99 you would need to spend ($499.99 for a Dyson = $124.99). So at that point... I guess the cooling value in your living space vs. the $80 vs. the noise?
I guess that would be the comparison. Essentially, take one vs one and say "Is the noise value better or worse."? ;s
How do know everything? 🎉
True Science 🧑🔬
Very interesting information considering I am looking to buy a circulator fan. Am I right to say the conclusion is that they work? What would be an ideal way to place them? I am looking to cool a rectangular space, with a door to the balcony which wind doesn't enter. Some said a circulator fan should be oscillating all over, some said to blow it toward the wall or the ceiling. Any advice?
It's time for construction. what you really want to to put a fan in the window but the screen is restricting the flow.
You need to remove the window screen and with your new design (to keep out the bugs), place the fan in the window to get the maximum cooling effect for the area.
In the thumbnail, the box fan's propeller looks like a Playboy bunny.
I've always wondered how much better a generic box fan would run with a proper case/box? A lot of wasted space around the fan blades. Maybe some day I'll turn one into a proper ducted fan.
The one time I experimented with that, it made no measureable difference. in terms of thrust, it may even make it slightly worse, because the fan blades often also suck in air from the side.
Did you per chance document energy usage?
Not in this video. But the dreo fans with their brushless DC motors use quite a bit less power than the other fans.
Was weight factored into the thrust rating? seems like it would be necessary in that testing config
No, fan itself doesn't move, and I tared the scale each time I changed fans.
Sehr interessantes Video!
The dyson is the only one with all the marketing and that the rest is true
So what’s the optimal distance for a box fan from a window/ screen door? Can you include distance between two windows/door
Random question, What if you added a diffuser(diverter) in front of the fan by leaving a 0.5 inch gap in front
Am i getting it wrong or is your simulation placing the fan outside the house?
Your blow AT the door (window) and measure how much air flow is in that room (house) and out of the next window.
Or can i use that analog by facing the fan to an outside window and hoping for the same result it sucking the air through the house into the other window?
blow air out, and air will have to come in somewhere else to make up for it
This must be one of those only fans videos I keep hearing about.
So, this video is Only about Fans?
I wish I had as much free time as Matthias.
Free time! He's working his tail off for this audience base.