Originally Posted by
Leigh Betsch
I like simple things. Rod and Danny have nice simple formulas. I don't need extreme accuracy just a general conclusion that it is a good idea or dumb idea to exhaust outside. So if I understand correct:
Assuming a 1200 cfm exhaust and 50 degree temperature change
Rod's formula: 1200*.02* 50=1200 BTU/min*60=72,000 BTU/hr
Danny's formula: 1200*1.08*50=64,800 BTU/hr
So worst case (72,000 BTU/hr)/3413 = 21.10 KW/hr
at $.10/kw = $2.11/hr
So if I wire my DC to start and run only when my woodworking equipment is running and if my equipment run time is 1/2 hr per weeknight and 6hrs per weekend it would cost about $17.94 per week to exhaust the DC to the outdoors.
So if my math is correct it would make economical sense to look into the other factors that people have brought up, including the safety concerns.
My shop is not part of my house and my nearest neighbor is 1/2 mile away so I probably have a few advantages along this line.
I'll probably give it a real world test this weekend, hook up my DC and see if the shop gets cold, and see how much the furnace runs.