Inside the Town of Vienna two of every three homes went up before 1980, back when a house was planned around its furnace. The cooling came later and borrows from the heat: the coil sits just above the furnace, and the fan a tune-up cleans is the furnace blower in the basement. It spent October to April pushing warm air, so by May its blades carry a winter’s dust, right when cooling asks it to move more air than heating did.
Outside, the condenser on an older town lot went wherever there was room the year the air went in: a side yard, a corner by the back steps, behind the shrubs. The Town’s crews vacuum leaves raked to the curb from mid-October through December, but the ones that blow in behind a condenser stay all winter and mat against its coil. Pulling them out and washing that coil is the first outdoor job of a spring visit here.
A quarter of the homes in town date from 2000 or later, many built where an older house came down, and the Town keeps a separate permit track for that infill work. Those houses usually split the cooling between two or three systems, and the bedrooms’ system hangs its air handler up under the roof, over a drain pan above a finished ceiling. Usually a float switch in that pan stops the system cold when it fills. The tune-up clears the drain before the humid weeks, when the coil pulls the most water.
Across the line in Wolf Trap, almost every home is a detached house, over a third of them built in the 1980s and 90s, and about two in ten owners heat with electricity. That’s mostly heat pumps, so the outdoor unit arrives at its spring visit after a full winter of heating and defrosting. Dunn Loring, with a 1977 median, sits at about the same electric share.