Various types of connectors are used in home appliances and air-conditioning systems to create reliable contacts between different parts of electric circuits. In recent years, the number and types of connectors have multiplied as advanced sensors, controls, and communication/networking capabilities are incorporated into more intelligent appliances.

Natural gas remains the dominant heat source in regions where electricity is at a high premium and natural-gas infrastructure has been established. Italy, for example, continues to prefer gas for its reliability and lower cost.