Vent free plaque heater uses natural gas or liquid propane. No conversion kit required. Thermostat valve for variable heat settings. Completely vent free with no outside duct or chimney needed. Unit is 99% efficient and has an ODS (oxygen depletion sensor) for safety. Plaque heaters operate just like the sun, providing direct, immediate warmth in the room. No electricity is required - perfect for use during power outages. Push button piezo ignition offers easy start up. PFS certified. One year limited warranty.