It does require ventilation. This is from their product pages;
Safety System:........................Power exhaust venting removes 100% of combustion by-products. Automatic Safety Shut-off Safety System:........................Power exhaust venting removes 100% of combustion by-products. Automatic Safety Shut-off in case of malfunction. No open windows are required. Operates safely at altitudes above 5000 ft.
Vent Kit...................................Vent kits have all necessary installation hardware included for most common installations. Includes 3 foot length (1 1/2" I.D.) flexible exhaust hose, exhaust vent terminal, remote wall thermostat, mounting screws, and easy-to-follow installation instructions. Chose between an exhaust thru-fitting , a sidewall exhaust terminal, or a stainless steel scoop exhaust terminal.
case of malfunction. No open windows are required. Operates safely at altitudes above 5000 ft.
Vent Kit...................................Vent kits have all necessary installation hardware included for most common installations. Includes 3 foot length (1 1/2" I.D.) flexible exhaust hose, exhaust vent terminal, remote wall thermostat, mounting screws, and easy-to-follow installation instructions. Chose between an exhaust thru-fitting , a sidewall exhaust terminal, or a stainless steel scoop exhaust terminal.