In this brief blog post in the 5 Gallon Bucket Air Conditioner - Does it work series, I am going to talk about fans.
The fan is THE KEY COMPONENT to these types of projects. It is the fan that will determine whether the device works or not. The fan design is critical.
So, there are 3 main things one needs to look at when it comes to fans. Namely, the power requirements, cubic feet per minute (CFM) output, and the static pressure. Think of these three requirements as 3 points on a triangle. If you change one, then the other 2 will HAVE to change.
So, there are many fan types, shapes, designs etc., but at the end of the day, they all do the same thing, move air. So, it is naive to assume that fan design for the 5 gallon bucket air conditioner is very simple, you want the fan that moves the most air, period. That is very simply is NOT the case.
I have read and have seen all of the other 5 gallon bucket air conditioners on the internet. I can assure you, not one of them, other than mine of course, is designed by an engineer who "knows what he's doing." It's obvious. Because, of that, the 5 gallon bucket air conditioner is getting a 'bad rap' because so many 'other guys' are giving negative reviews, saying it doesn't work, etc. You won't hear that about my units. These things work. Because they are specifically designed, component by component to work as a system, for maximum performance.
The fan is the most crucial piece of this puzzle.
So, I see a lot of guys talk about using large "endless breeze" fans or even a Honeywell "turbo" fan etc. Beside the fact these things are huge and not aesthetically appealing, they don't work as well as my fans do. There are videos of little tassels and streamers showing the air flow etc. One may wonder why I don't show that on any of my videos? Simple, my fans produce so much pressure that it would rip the streamers right out of the tape, and the streamers would be 10 feet long and still blowing strong as they are blowing across the yard!
That's because, the key to these units is the fan pressure, not the air flow.
I read over and over, and I have to chuckle, about how these DIY guys, want bigger fans that move more CFM etc. Then I read where they found a fan that will move 900 cfm, and only draw 1.5 amps of current. That is comical.
I'm not saying there aren't fans that draw 1.5 amps of current, and move 900 cfm of airflow, I'm just saying, those fans won't work effectively for THIS purpose.
So, here are some pretty basic engineering principles that I am going to try and make as simple as possible for you to understand.
The first one is pressure.
Think of 2 square chambers, equal size, mounted side by side, connected with a small pipe. One chamber has high pressure in it, and one has low pressure. Obviously the pipe connecting the 2 chambers will EVENTUALLY put the 2 chambers at equilibrium pressure.
Now let's make that pipe, smaller and smaller, and in fact let's make that pipe so small that is considered 'an orifice' rather than pipe. Let's say that the orifice diameter is measured in thousandths of an inch rather than in inches.
Now, let's say that the pressure difference between the 2 chambers is less than 1 psi, when we open the orifice.
Now, how long will it take for the 2 chambers to equalize, assuming the chambers are very large?
A long time right? There simply isn't much pressure difference, and the orifice diameter is very small.
Now, let's change the scene a little bit. Now let's have the same situation, but let's make the pressure difference between the 2 chambers large, like 200 psi. Now what happens when the orifice is opened up? The air will be "screaming" going from the high pressure to the low pressure, right? There will be huge velocity going through the orifice, NOT A LOT OF AIR, but very fast air.
There are obviously many calculations on orifice flow, and orifice flow geometry, and orifice design and shape etc. But, for our overly simplistic example, one can see that at least in this example, there would be very high velocities of air flowing through our orifice.
So, now, how does one get such high pressure into the high pressure cylinder? This is where a pump comes into play. When thinking of a pump, think of it as something converting power into pressure. That power can be electrical power, can be chemical power, mechanical power, any kind of power, and then converting that power into pressure. In our case, that pressure is air pressure.
So, in most cases, one would use electrical power, to compress the air, and then use that compressed air to pressurize the "high pressure" chamber. There is no other way to create pressure, without power.
Ok, so now, with those basic understandings of power, pressure, and air flow, we can go back to talking about fans.
One can see, that with enough power, there can be a lot of pressure, but not necessarily a lot of airflow. The flipside is also true, if you use your power to move a lot of air, there won't be a lot of pressure.
So, now, with that basic understanding of engineering, you can now see where these DIY guys are talking about 10" fans that draw 1.5 amps and blow 900 cfm, that there is not any pressure. To put that in comparison to the 5gallonairconditioner.com fans, they draw over 4 amps of power and flow 250 cfm of air.
To compare the fans, my fans draw 3Xs the power, and blow 30% of the air, so what does that mean? That means that they have MASSIVE VELOCITY due to the very high pressure as compared to these other designs being touted on the internet.
Another way to think about it, is to place one of the competitors fans next to a book, and turn the fan on. Their fan will blow a lot of air, and may flip a few pages in the book. My fan? Flip the book over end over end and blow the entire book off the table, ripping pages out as it's doing so.
So, why is this important? Why the need for such pressure?
It is because of this pressure that makes the 5gallonairconditioner.com units work, and none of the others do.
So, to answer the question, 5 gallon air conditioner, does it work? The answer is, Yes !!