Venting dc outside

[Michael W. Clark]

Well let me ask it this way:

If you pick it up and set it back down... say, 100 times. (lets assume in the same spot)

Did you do any work?

Carl,
Work = Force x Distance. If you apply a force to an object and move it, then work was performed. Even if the object returns back to the same place it started, it still traveled a distance.

I wasn't trying to be smart when I posted this, but wanted it to lead into the statement by Phil and others. Moving the air around in the shop takes energy and a large percentage of the electrical input of the DC motor goes into moving this air. A relatively small percentage is converted to heat due to the electrical inefficiency of the motor and drive losses at the fan.

As far as the air being heated from duct friction, I just can't buy into it without more thought or emperical data. I understand the concept that the duct friction is imparting heat into the air, but honestly, I have never measured a temperature rise in the airstream between two points when there was just ductwork and no outside influence.

Mike