How do Buck Stove infrared heaters not require a vent or chimney?

Hello, thank you for reaching out. Buck Stove infrared wall heaters are vent-free gas heaters, they do not require a traditional chimney because they are unvented units that use oxygen from the room, and adequate combustion & ventilation air must be provided for the units to work. The heaters are also equipped with an Oxygen Depletion Sensing (ODS) safety shutoff system that shuts the heater down if insufficient fresh air is detected. If you have additional questions, please feel free to reach out over the phone to our Customer Service line at 1-888-901-5460. Have a great rest of your day.