Belly ducts, attic flex and a 1940s plenum: what a duct-cleaning day looks like across three Live Oak house types

Three eras of ductwork

Ductwork in Suwannee County comes in three main kinds, and each matches an era of house.

The downtown bungalows between Ohio Avenue and the courthouse, built from the 1900s through the 1940s, were heated by floor furnaces and fireplaces and had ducts added later, often a sheet-metal plenum in the crawlspace feeding floor registers through short runs. Seventy years of living has dropped everything imaginable into those registers, and the crawlspace side has been breathing damp air the whole time.

The 1960s-to-2000s houses, from the block ranches of Sherwood Forest to the River Woods subdivision, mostly have flex duct in the attic. Attic flex sags, kinks, pulls off its boots and leaks at every joint, and it runs through an attic that hits 130 degrees in July. What is inside it is dust and insulation fibers pulled through those leaks.

The manufactured homes, nearly half the county’s housing, have a belly duct: a long insulated trunk under the floor, sometimes with a crossover between two sections of a double-wide. It hangs from the frame, and when a strap lets go or an animal gets in, it tears, fills with sand and water, and starts pulling air from the dirt.

Where the truck goes on a duct day

8:50 a.m., a bungalow off Howard Street. The owners want the ducts cleaned before a new baby arrives. The technician starts not with the brush but with a camera down each floor register and a look at the plenum from the crawlspace. The runs are intact metal, dusty but sound. This house gets a true cleaning: registers pulled, each run agitated and vacuumed to a negative-air machine, the plenum wiped, the return sealed where it gapped at the furnace.

11:15 a.m., a two-story in River Woods. Complaint: dust everywhere, two bedrooms always warm. In the attic, one flex run is kinked flat against a truss, another has pulled halfway off its boot and is blowing into the insulation, and the return plenum has a gap the width of a hand. Cleaning would be pointless. This house gets the runs re-hung and reconnected, the return sealed, and then a cleaning of what remains.

2:30 p.m., a double-wide near Wellborn on SVEC power. The system runs constantly and the house never gets cool. Under the home, the belly duct has torn open along six feet and is lying on the sand, and the crossover has collapsed. There is nothing to clean. This house gets a quote for a new belly duct and crossover, and the owner gets an honest explanation of why the package unit on the roof was never the problem.

The gear that comes in

A Cook’s duct visit brings a negative-air vacuum that pulls the system under suction while the runs are worked, rotary brushes and air whips sized to the duct, an inspection camera, a duct leakage tester, a static pressure gauge, mastic and foil tape for sealing, hangers and straps for re-hanging flex, and drop cloths and register covers to keep the house clean. On a manufactured-home day, add a creeper, belly-duct material and the tools to drop and reinstall skirting.

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What we find under and over Suwannee County houses

The same discoveries repeat across the county.

• Returns pulling from the wrong place. Attic air in subdivisions, crawlspace air under bungalows, dirt-and-sand air under manufactured homes. The dust in the house came from there.
• Flex runs crushed, kinked or disconnected, which look on the thermostat like a weak air conditioner.
• Sweating ducts in crawlspaces and attics, dripping onto insulation and growing mold on the outside of the duct, which no cleaning reaches.
• Rodents and insects in belly ducts and crawlspace plenums, especially on acreage and river lots.
• Pollen and construction dust in houses that have been renovated or sit near a dirt road.
• Flood silt in the ducts of river houses from Suwannee Springs to Branford after a high-water year.
• Filters that stop nothing, one-inch fiberglass in a return that could hold a real cabinet.

Cleaning fixes the pollen, the dust and the debris. Repair fixes everything else on that list, and repair is what most of the day turns out to be.

After the cleaning

Each duct visit ends with a static pressure reading and a leakage number, written down, so the house has a baseline. The homeowner gets a filter recommendation sized to the return, a note on which ducts were cleaned and which were repaired or re-hung, and a plain opinion on whether the remaining ductwork has years left or is on the list for replacement at the next equipment change. Cleaning is not on a calendar here; it happens when there is a reason. Sealing and repair, done once, usually hold until the house changes.