I bought a 5hp single phase 220v motor today for the sweet sum of $100 from a guy on Craigs list. He had bought it for his metal lathe but then he never removed the 3 phase motor is has ,and then bought a convertor for it.
Motor is used, but sure doesn't look like very much, no bad smells in the winding hole. Bearings are smooth and quiet. This puppy will make the 30" axial fan move a lot of air, around 12500 @ 1.0 according to the manufacturer.
Was going to use a 3hp with vfd on the axial fan, but since I acquired a pair of centrigual fans I am going to use 3hp's and vfd's on the intake air and let the pressure transducer tell them what speed to run.
Theory is the 2 fans have a greater output than the axial fan.
IF theory proves out then I will be to go positive or negative in a couple seconds notice, like when someone opens the door while the booth is in use and is a bit negative.
Bam- vfd's speed the intakes up and air is pushed out the open door instead of sucked in
.
2 motors down, 1 more 3hp 3ph and another vfd to acquire.
Worst case scenario the axial draws more than the intakes can put out, a simple recirc duct from the discharge back into the intake with a dampener cures that, and gives the option to add an actuator to the dampener and control it with the vfd brains.
Sure a good thing I have friends that work in the commercial hvac bidness. No way I would know how to program it