An outside air kit brings in a continuous supply of combustion air from outside your home straight to your stove. While it is not always required to use an outside air kit, it is highly recommended. There are some situations where an outside air kit is absolutely required, for example when the appliance is located in a mobile home. outside air kit are also sometimes required by local code. Please refer to your local Quadra-Fire dealer to learn more about outside air kit and if your city code requires you to use one.