Furnace replacement in Springfield.

Gas climbs the older the street gets. In Kings Park and North Springfield close to nine in ten owners burn it, and in Ravensworth, the small 22151 neighborhood where the typical owner home dates from 1964, nearly every one does. North Springfield’s typical owner home went up in 1957 and Kings Park’s in 1966, so the furnace in those basements today replaced one that had already replaced the original.

Many Springfield houses run a furnace and outdoor unit bought years apart. When the condenser’s label shows R-410A or one of the new A2L refrigerants and it went in during the last decade, keeping it usually makes sense; the new furnace then sits under the existing coil, so its cabinet width and blower have to suit that coil. An R-22 label means a unit most likely set before 2010, and then the pair, $8,898 to $23,000, is the better quote.

The bigger choice in a 1960s Springfield basement is how the new furnace breathes. A standard efficiency model can keep venting up the masonry flue it shares with the gas water heater. A condensing one pipes its exhaust through the nearest outside wall in PVC and sends its condensate to a floor drain or a small pump, and once it leaves, the water heater may be drafting by itself up a flue built for two appliances. Washington Gas, the gas company for most of Fairfax County, pays rebates on furnaces rated 95.1 percent AFUE or higher, in two tiers.

West Springfield runs about two thirds gas, and close to four in ten of its homes are townhouses, where the furnace usually stands in a lower-level utility room at the foot of a narrow stair, and that path gets measured before pricing. About one Newington owner in a hundred burns propane, and those furnaces are ours to replace too.