Originally Posted by
Chris Friesen
As a thought experiment...I'm in Canada, it hit -35 C in February. Hypothetically speaking, as a worst-case if I'm pushing 800CFM out of the building at 15 C then I would need to warm up 800CFM of air by 50 C. The specific heat of air is 1006 J/(Kg*K). The density of air at -15 C is about 1.35 kg/m^3. That works out to 25.6 KW of heat energy, or 87000 BTU/hr. (Thanks to Google for doing all the unit conversions!)
I pay about 14 cents per KWhr, so it would cost at most $3.60 per hour of running the dust collector in extra electric heating energy if I vented outside. I actually have gas heat, so that would drop to more like $1.20 per hour.
That's the absolute worst-case. If you can mix the air less, or the temperature difference between inside and outside is less then the numbers go down.
Thanks for the math Chris. I am definitely going to vent outside. I am also using gas, in floor hot water so it should be less.
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