The definition of a kitchen make up air system is a ventilation system that provides fresh air to the kitchen. This system helps to reduce the amount of air pollutants and odors in the kitchen, as well as reducing the risk of fire. It also helps to maintain a comfortable temperature in the kitchen, and helps to reduce the amount of energy used to heat or cool the kitchen. Kitchen make up air systems are designed to be efficient and cost effective, and can be used in both residential and commercial kitchens. They typically consist of a fan, ductwork, and a filter to help keep the air clean. In some cases, the system may also include a humidifier to help keep the air moist. Kitchen make up air systems are an important part of keeping the kitchen safe and comfortable, and are essential for any kitchen.