View Full Version : Exhaust blower is chilling me.

Tom Majewski
01-27-2007, 11:44 AM
As it was 17 degrees here at night and I'm running the laser in my basement, I was getting ill thinking of how hundreds of cubic feet of warm air per minute I'm sucking out of my house. All that negative pressure is drawing more cold air in through the leaky 150 year old farmhouse.

So does anyone know if putting a blast gate - semi open to just draw out only as much air as I need, instead of full force will overheat the blower motor. It's a Penn State 3/4 hp unit.

I can feel it noticeably colder in the basement after running for 20 minutes.


Joe Pelonio
01-27-2007, 12:14 PM
I wouldn't mess around with the cooling function of the fan, as expensive as replacement tubes are. My suggestion is to slightly open a window, if you have one near the laser. If no window maybe install some sort of vent that can be opened to allow outside air to be drawn in and through the laser then out the exhaust. That will prevent it from sucking out the warm air from the rest of the house. The air has to come from somewhere, with no intake it's going to come from the house. I keep a window in my shop near the laser (right behind it) slightly open while running it and there's a cold draft in that area but the rest of the room is OK, and you can always wear long sleeves while working. I'm doing a few jobs this morning and it's 27 here.

Guy Hilliard
01-27-2007, 12:20 PM

A heat exchanger would work better at saving energy but the blast gate will work to limit flow. A TEFC motor will not overheat under that condition. When the blower is working against a partial vacuum it is actually doing less work then with an open pipe.


Martin Reynolds
01-27-2007, 1:15 PM
I'll second Guy's comment. When I was testing my setup, I put a power meter on the systems to make sure that I wasn't going to trip breakers. A fully open blower runs 600W or so, with the blast gate closed just 200W.

Opening the widow a bit makes a big difference.

Kim Vellore
01-27-2007, 5:36 PM
I had the same problem so I did this



Bill Cunningham
01-27-2007, 8:50 PM
How well the direct input to the front of the laser would work, depends on how much water is in the icy air as it condensates on your electronics :eek:.. I just consider the heat loss as the cost of doing business.. But, my shop is in another building and I'm not sucking the heat out of my house which is really a much bigger problem!!