Furnace tune-ups in Marshall.

Only about eight owner homes in all of 20115 heat with utility gas, so a Marshall gas furnace runs on propane from a tank in the yard: about one owner home in five, a bit over 400 houses. Most of the rest heat with electricity, usually a heat pump, and a heat pump gets the same fall tune-up for the same $99 a system.

In the village, the furnace is younger than the house by generations. The County’s plan lists stone, frame and brick buildings on West Main Street from the early 1800s and two-story I-houses from 1900 to 1920. A propane furnace in one of those often sits in a cellar and vents up an old masonry chimney, which spends the summer collecting leaves, crumbled mortar and the odd nest. Among the safeties the tune-up makes prove itself is the switch that shuts the burners down when exhaust isn’t clearing.

Marshall’s ground adds wear of its own. The plan maps soils with a seasonal high water table 10 to 40 inches down and says houses with basements there should be sited to keep groundwater out. A furnace on a floor that’s damp half the year rusts from the bottom, and the scale can drop onto the burners. The tune-up looks at the burner compartment and the cabinet base; if the furnace ought to be raised onto a pad, that goes in the findings with a price.

North of Main Street and west of Rectortown Road, where most houses date from the 1970s through the 1990s, a propane furnace there is often the house’s second or third. Fall is when field mice look for somewhere warm, and a quiet furnace cabinet suits them; a nest by the blower or a chewed control wire is what a fall look finds before a cold night does.