This stove is EPA-certified to burn with 82% efficiency. Heat exchanger design and powerful room blower produce maximum heat from pellets. Pellets burn so completely that the ash drawer needs to be emptied only every two weeks. Five power settings allow 20 hours of continuous burning on the lowest burn setting. A 7-day programmable thermostat allows constant temperature economical pellet use. The rear exhaust is through a 3" double-wall pipe, intake is through a rear-facing 2" pipe. An included blower circulates warm air throughout your home, maximizing the stove’s heating power.