Ductless mini splits in Catharpin.

The Census sorts ZIP 20143’s 334 owner homes into detached houses, and about four in ten went up before 1980, one in five before 1960. Houses that old were often built with limited ducts, and the median build year of 1986 leaves plenty of room for additions since. A ductless head heats and cools a single room without a duct: a sunroom, a finished basement, a bedroom that lags behind the rest.

In the electric-heat houses, nearly half the owner homes here, a head can replace baseboard in a room and add cooling to it. In a propane or oil house, it gives one room its own electric heat and cooling without extending ductwork from the system you have. Each head is a zone, and each zone gets its own setting on its own remote.

Dulles averages a January low of 25.2 degrees and logs 101.7 nights a year at or below freezing. Snowfall totaled up to 30.0 inches near Bull Run in January 2016, and large trees came down near Catharpin in June 2020. So the outdoor unit’s spot matters: ask for a wall bracket above the snow line and clear of limbs, not a low pad under a tree.

Prince William County lists work that alters a home’s heating and air conditioning as permit work, which is where a new ductless system lands. The exemption covers swapping an electric furnace, heat pump or condensing unit for the same type in the same spot, not a new head in a room that had none. We can say how your project lines up when we quote it.