CFM vs Pressure Drop help


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Old 05-20-13, 08:35 AM
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CFM vs Pressure Drop help

I am looking at specifying an evap coil. I noticed that there are a couple of coils that Goodman makes and I'm a little confused about the CFM vs Pressure Drop.
These are 2.5 ton units CAPF-F3131B26 which has a 0.061" wet drop at 800CFM vs the CAPF3030B6 that has a 0.150" wet drop at 800CFM. Is there a reason to go with one over the other?
Thanks in advance for your input!
 
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Old 05-20-13, 09:17 AM
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There are a lot of factors that affect the pressure drop of an evaporator coil; however, it is difficult for me to believe that there would be that much difference in the pressure drop between those two coils. That low figure appears impossible to achieve...

The choice of coils depends largely on the purpose or objectives that you are seeking for your system to achieve. If the pressure drop drives the static pressure to high for the air handler to cope with, then you would probably want to go to the lower pressure drop coil.

These newer higher efficiency coils have larger pressure drops than older coils, and some larger tonnage coils can be way up in the .45 pressure drop categories which doesn't leave much room for your filter and your other pressure drops in the system.
 
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Old 05-20-13, 11:27 AM
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Thanks for the reply. I noticed that the coil with the lower drop also has a larger sq ft face area (4.2 vs 3.75) which accounts for the difference. But the 3 ton coils also only have 3.75 sqft areas. You need to get to the 3-3.5 ton coils before the area goes up to 4.2 sqft.
Is there a good reason to ever go with the higher press drop coil?
 
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Old 05-20-13, 07:19 PM
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Is there a good reason to ever go with the higher press drop coil?
Usually, they might be more efficient at absorbing heat.
 
 

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