What type of current is primarily used in residential HVAC systems?

Residential HVAC systems primarily use single-phase alternating current (AC) for their electrical needs. This is due to the common electrical supply in most homes, which typically provides single-phase power. In a single-phase system, the electricity flows through one phase and is characterized by a sinusoidal waveform, making it suitable for the standard voltage levels used in household appliances, including HVAC equipment.

Single-phase AC is commonly used in smaller appliances and heating or cooling units that do not require the higher electrical demand found in larger commercial systems. It is effective for the operation of air conditioning units, furnaces, and heat pumps in a residential setting, making it the standard choice for these applications.

Three-phase AC is more common in industrial and commercial applications where larger motors and equipment require higher efficiency and power capacity, but it is generally not necessary for typical residential HVAC systems. Direct current (DC) is used in some specific applications, such as certain types of fans and controls, but it is not the primary current type for HVAC systems. Pulsating current may be encountered in some specialized electronic circuits, but it does not represent the standard supply used in residential HVAC systems.