In the Burke Census place, which takes in Lake Braddock and Burke Lake Road, about 6 in 10 owner-occupied homes heat with gas and about 6 in 10 went up before 1980. Most are single-family, with the furnace in a basement or utility room, often not the first one to stand there. Washington Gas supplies most of Fairfax County, and the gas pressure at the furnace leads our list of readings.
There the air conditioner’s coil usually rides on top of the furnace, so all the winter heat passes through it. A coil packed with summer dust, or a filter last changed in August, chokes that air. Short of air, a gas furnace runs hot until a limit switch shuts the burners off, and the house swings between warm and cool. Temperature rise, how many degrees the furnace adds to the air moving past it, catches that early.
Inside Burke Centre only about 3 in 10 homes heat with gas, and plenty of those 1980s and 1990s furnaces have been traded for high-efficiency ones that exhaust through a wall in PVC. The Conservancy’s Architectural Standards keep gas appliance vents out of street view, on the rear or side of the house wherever possible. A pressure switch won’t let the burners light when those pipes can’t breathe, and proving it still works is part of checking the safeties.
The other 7 in 10 Burke Centre homes run on electricity, mostly heat pumps whose backup is a bank of electric strips: no burner, no flue, nothing for a gas gauge to read. A Burke Centre heat pump like that still gets a fall tune-up, at the same $99 a system as a gas furnace.