While in the process of some extensive home remodeling, I thought I would add a whole-house attic exhaust fan. We enjoy a couple of months on the either side of summer where opening the windows and drawing air into our home is very comfortable.
The attic fan pulls in outside air and exhausts house air into the attic, which, in turn, helps to cool the attic. There is a louver assembly that uses gravity to keep the louvers closed, and when the fan is on, the airflow opens them. It saves energy over having to use the HVAC central system.
I picked up a three-speed fan at a local discount outlet for about $100. Installation was easy, and everything looked great. The fan was in place, the louvers were hung, and we were ready to test it. I pulled the cord, and the fan started, the louvers opened, and the air flowed. I walked out of the room to seek praise for my efforts when I heard a noise behind me. Running back down the hall, I found the fan had shut itself off. Then I noticed the pull cord, which had hung down from one side of the fan and through a hole in the louver surround. It had been sucked up through the louvers.
I pulled the louvers down and discovered the fan blades had caught the pull cord and cut the end off, thus shutting off the fan. I had turned the fan on to the lowest speed. It was pull once for high, pull again for medium speed, pull once more for low, and then one more tug to turn it off. It pulled the cord and the little weight at the end of it right up into the blades! Who designed this? Who tested it?
My solution was to completely remove the control switch and run wires down to a wall-mounted three-way rotary switch located out of harm's way. After this experience, I decided against putting one of these in the bathroom.
This entry was submitted by Bradley Miller and edited by Rob Spiegel.
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Good point, Jmiller. It sounds like he was taking a window fan and using it as an adict fan. Certainly a fan mounted in the attic. Certainly you wouldn't need three speeds for a fan way up in the attic.
I have seen this same thing happen several times with Pedistal fans. (having had to replace the switches, if the motor did not burn up) (Pedistal fans are the larger fans more for industrial use, that stand about 6' tall, or like you see in many exercise places to move the air around.)
I have seen it suck up the cords when someone attaches a light string onto the chain, it sucks in the string and then the chain. Normally, the fan has a wire surround guard that the blocks the chain from going into the fan. Air flow is insufficient to lift up the chain and suck it between the wire mesh, but add on a light string and there you go. I even had someone add on the string, had this happen, removed the string afterwards and stated it was never there. He had just thrown the string in the nearby trash can, and when I looked, there it was.
I have also seen this happen when the fan was placed into a Boxed-in frame. This helped to create more air flow immediately around the motor housing (which the chain come out of) and sucked in the chain.
And then there are those who do not test what they sell, as others have advised. Seems everywhere you turn, you find something that could have been made more user friendly with only minor changes. But with mass produced off shores junk being imported, actual testing is very limited. And any part that is heavier add a fraction of a cent to cost...
In my experience one of the biggest failures of engineers is not going down to the lab and putting there hands on the finished product. In so many companies you write some kind of test request and someone else does the test. Engineers should be right in there helping with or definitely monitoring any test results.
Another failure of young engineers is to not understand how their components or systems affect the next guy down the line.
Further, how many times do companies actually take the time to do a good design review and/or design failure mode analysis.
I think this may also be an example of the failures that can occur without proper project management. Sometimes the system just isn't set up to allow someone to take into account how everything goes together. It seems like we bog our project managers down with so many presentations to upper management and cost analysis and other non-productive stuff that they don't have time to do simple design reviews. Kind of sad. Good example of what not to do, though.
Interesting that it appears the entire ceiling fan market has issues. I wonder at what price point does the american market place start to pay more for higher quality. Will we pay more for a higher quality toothbrush. probably. Will we pay more for a higher quality car, absolutely. But when it comes to that $50-$125 price range it appears we will pay for what we get and not complain. Until we start to vote with our dollars and communicate to businesses that we will pay for qualiy, we are doomed to stay where we are.
Seems like a problem like the amount of weight on the fan pull cord is a hard thing for a company to miss. It's certainly not a matter of cutting corners. I guess it must be a matter of just not thinking.
All the ceiling fans in our house, some dating more than 20 years have split phase motors. And, to the best of my recollection all of them were manufactured either in Taiwan or mainland China, so I'm NOT talking American-made HUNTER or CASABLANCA (now defunct!) units. Yet, when I inspect the chamber where the direction switches & speed control swithes are housed, I see there is a multipole capacitor with the approx. values of 2 uf, 5 uf & 8 uf. So, one would assume that these are switched into the winding to provide the additional phase shift to change the fan motor's rotational speed.
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