Please read this Important Notice. The Modine Hot Dawg® Model HD power-exhausted, gas-fired unit heater is compact, light, and quiet which makes it great for garage installations.
Separated combustion draws outside air into the unit combustion chamber where it is burned with the fuel and then vented out with the exhaust. Reduces the common concerns about dusty, dirty, humid or aerosol environments.
Power Vented (or open) combustion pulls the the combustion air from inside the building and pushes the exhaust gases outside using a blower.