Rheem/Ruud blower motor specs

[Obi-Wan]

I'm looking to put an exhaust fan inside my insulated/heated 30x40x14' workshop to help draw air through on hot summer days. I have the old squirrel cage furnace fan that was in our home furnace (3-ton unit for 4000-sq-ft (incl basement) home). The unit was first installed in 2003, and the motor has 4 speeds. Squirrel cage fans are generally quieter than standard fans, so I'd like to use this if I can. The math I've seen says I need at least 8 air changes per hour, so I'd like to get 3000 CFM if I can.

The problem I'm running into is figuring out the CFM rating of this blower based on the stickers that still remain on the unit. Can anybody help me find the specs on this unit?

The assembly housing is aprt 61697-50, like this:
https://www.hvacpartsshop.com/as-61697-50-blower-assembly/

The blower wheel itself is model number 70-22688-01, like this:
https://www.americanhvacparts.com/p-19892-7-14-w-x-12-dia-blower-wheel-rheem-ruud.aspx

The motor is model number 51-24070-02, a 1/2-hp, 1000-rpm, 115V unit, like this:
https://www.amazon.com/dp/B003U4KEIQ/?tag=atomicindus08-20

The motor's not sealed, but I'm not painting cars or using lots of oil-based finishes, and the workshop should be relatively clean except for occasional sawdust. Have any of the rest of you used old furnace fans as shop exhaust fans?

 

[Obi-Wan]

And, of course, as soon as I posted my question, I found my answer. This online PDF:

https://api.ferguson.com/dar-step-service/Query?ASSET_ID=4572636&USE_TYPE=PARTS&PRODUCT_ID=1600787

lists the CFM for that assembly at just 1100-1300 CFM, which is less than half of what I'd really like to have. I assume that's on high speed. That surprises me, given that it came out of a home with 50% more cubic feet of space than my workshop will have. I guess TPTB think my workshop needs three times as many air exchanges per hour as my home does.

That's disappointing. Still, have any of the rest of you had good luck using home furnace fans in your shop?

 

[bazar01]

That's about right at 400 cfm per ton.

 

[LS6 Tommy]

ACH for an exhaust fan is different than ACH for cooling. For comfort cooling you're recirculating existing air. The minimum CFM rating is to provide proper cooling. For an exhaust system, you're replacing the air completely.

Tommy

 

[nadogail]

Thanks for posting.