Two stage evaporative cooler motor question


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Old 04-13-19, 06:21 PM
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Two stage evaporative cooler motor question

Hi everyone I'm new here and looking for a little help. I'm building a two stage evaporative cooler and I was wondering about the motor on my primary fan. I picked up a large industrial exhaust fan I was planning to use for my main blower, it's a Dayton 3CC75 a 36" fan with a 1/2 horsepower motor currently attached. When looking up specifications it looks like this fan was rated for a motor from 1-5hp, however the RPMs of the 1/2hp motor are the same... Is there a benefit in purchasing a larger (more hp) motor?
 
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Old 04-14-19, 02:23 AM
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The fan you are referencing can be powered by any motor from 1/4HP to 1.5 HP.according to Dayton. The actual required HP of the motor is dependent upon the RPM and the amount of the " resistence to flow" that you apply to that fan blade. You can use the 1/2 HP motor in your project if it will supply the correct amount of air flow and the amperage of the motor is not above the rating on the name plate.
 
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Old 04-14-19, 09:29 AM
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Thank you! How would I go about calculating resistance to airflow? It will have a very short duct and I was simply planning on ensuring the area was equal at the inlet and outlet. Approximately 726 insq.
 
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Old 04-14-19, 10:59 AM
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Unfortunately you are dealing with an unknown system there. I'm not sure you could calculate the air flow resistance. Once you have the fan and motor in place you'd measure the motor current draw but if it was too high you'd need to change the motor. I would think for that application.... based on similar units.... that 1/2hp would be ok..... but that's just an opinion.
 
 

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