Can you get your hands on the T&B reports to find out what cfm you should be moving with that fan and the others that you are having trouble with? If so I would go that route.. If its not a voltage or a mechanical issue, I would be inclined to think that it is an airflow issue.. Good luck buddy. Let us know what you come up with..
How negative is the space? Do the front doors of the building whistle or are they hard to open?
no not at all.
Originally Posted by desert guy
A fan motor that is pulling excessive amps is either defective or doing more work than it was designed to do. You have 99.9% eliminated the first possibility by replacing the motor. If this is a long established system and the problem is just-now-new - then something has changed in the system to reduce resistance to air flow.
So, as I see it the options are these:
1. The best method is reduce the blower speed by adjusting the drive sheave to a smaller effective diameter until the amp draw matches the FLA / RLA listed on the motor's name plate.
2. The other way is to reduce the max allowable amps / motor speed by altering the freak drive's parameters.
3. Find out why and how the air system has changed in a way which has resulted in a lesser resistance to air flow.
What do you mean: "return fan motor" ? Is this a push/pull system in a large air handler or packaged unit?
Originally Posted by Onefast450r