How is combustion air supplied to gas appliances?

Combustion air is essential for gas appliances to operate efficiently and safely. The correct method of supplying combustion air is through natural ventilation or ducted systems. Natural ventilation involves the influx of air via openings or vents that allow fresh air to enter the space where the gas appliance is situated, while ducted systems use a series of ducts or air intake systems designed to channel the necessary air supply directly to the appliance.

This approach is critical because it ensures that there is a sufficient and continuous supply of fresh air needed for the gas to combust properly. Proper combustion is necessary to optimize appliance efficiency and reduce the risk of hazardous situations, such as the production of carbon monoxide.

The other methods mentioned do not adequately provide the required combustion air. Electric fans can assist in maintaining airflow but are not the sole source of combustion air and are not universally applicable for all gas appliances. Open windows might provide some air but are not a reliable or safe means for controlled combustion air, especially in colder climates or during seasonal changes. Lastly, sealed units may have their own design standards for combustion air but are not the exclusive means of supplying air to gas appliances as various appliances require different configurations for air supply.