ductless

Ductless, in the context of heating and cooling, refers to systems that do not use ductwork to distribute conditioned air. The most common form is the ductless mini-split, consisting of an outdoor condenser connected by a small conduit to one or more indoor air-handling units.

Key components include the outdoor unit, one or more indoor air handlers, a refrigerant lineset, a condensate drain, and an electrical conduit. The system employs a refrigeration cycle to move heat between indoors and outdoors. In cooling, the outdoor unit rejects heat; in heating, some models reverse the cycle to extract heat from outside air. Thermostats or remotes control individual indoor units.

Zoning is a major feature: multiple indoor units linked to a single outdoor unit enable different rooms to be heated or cooled to different temperatures. This can improve comfort and reduce energy waste, particularly in homes with uneven loads or additions without existing ductwork.

Advantages include high energy efficiency, reduced energy losses from avoiding ductwork, easier retrofits, and flexible placement. Downsides can be higher upfront cost per zone, outdoor unit noise, and aesthetic considerations. Proper sizing, electrical requirements, and professional installation are essential; incorrect installation can negate efficiency gains or cause refrigerant leaks.

Most ductless systems offer high efficiency ratings (seasonal SEER, heating season performance HSPF). Regular maintenance involves filter cleaning, coil cleaning, and ensuring proper condensate drainage and refrigerant integrity. They are widely used in homes without existing ducts, room additions, and small commercial spaces.