Furnace and heating repair in Rectortown.

Fauquier County’s building criteria put the winter design temperature, the cold a heating system is sized for, at 17 degrees. The nearest NOAA normals station, outside Warrenton at nearly the village’s elevation, averages a January low near 25, about 98 nights a year at or below freezing and about five at or below 10. On those few bitter nights a heat pump leans on its electric backup strips, and that’s expected. One that needs the strips at 35 degrees has a problem.

Across the 20115 ZIP that most Rectortown homes share, electricity heats close to two in three owner homes and propane about one in five; natural gas, fewer than one in a hundred. So no heat here usually comes down to a defrost control that stopped clearing the coil, a burned element in the backup strips, or a propane furnace that lights and drops out.

The big storms test the outdoor unit. NOAA’s records put the January 2016 blizzard at 24 to 36 inches across northern Fauquier, and a February 2016 ice storm coated the same zone in a fifth to a third of an inch of ice. A heat pump buried in a drift or sealed in ice can’t pull heat from the air. Clear the snow off its top and sides, and never chip ice off the coil with a shovel; the fins bend before the ice gives.

The propane tank in the yard brings its own winter chores: keep the drive open after a snow for the delivery truck, and check the gauge before a cold week. Every furnace also needs electricity for its igniter and blower, so when trees and wires come down, as they did across the county in the March 2018 nor’easter, the heat stops with the lights. When the power returns and the heat doesn’t, check the breaker first, then call.