When the Ocala Electric bill climbs and the registers whistle, the ducts are usually leaking, not just dirty

The bill, the whistle and the attic

Inside Ocala city limits, Ocala Electric Utility serves about 56,000 customers, and the summer bill is how most duct problems announce themselves. The house has the same people in it, the thermostat sat at the same number, and the July bill is up again. The system runs fine. It just runs all afternoon.

The second clue is sound. A whistle or hiss at a supply register, or a sucking noise at the return grille when the system starts, is air being forced through a gap that shouldn’t be there. The third is dust: a gray halo on the carpet around floor registers, or on the ceiling around a supply, that comes back a week after cleaning.

Put those together in a house built before 1990, and the diagnosis is almost always the same: the attic ductwork is leaking. In Ocala’s 1970s and 1980s block ranches, the supply runs are flex duct in an attic that hits 130 degrees in July, joined with tape that let go decades ago. Cooled air leaks out into the attic on the supply side; superheated, dusty attic air gets pulled in on the return side. The system cools the attic a little and the house less, and the bill shows it.

That’s why half of our Ocala “duct cleaning” calls are something else. The dust is real. It’s just a symptom.

What duct cleaning is not

It is not a fix for leaking ducts. Cleaning a duct that pulls attic air through a gap at the plenum is a clean duct for about a week.

It is not a cure for a musty smell that comes from the coil. If the smell is strongest when the system starts in August, the growth is on the evaporator coil and in the drain pan, not in the duct, and the fix is at the air handler.

It is not a humidity fix. A house that feels damp at 74 degrees has an equipment problem, often an oversized heat pump, and clean ducts won’t change it.

It is not something to do every year. A sealed, properly filtered duct system in Ocala might need cleaning after a renovation, a pest problem, a flood like the June 2023 one that put water into low-lying houses, or a decade of dog hair. Not annually.

And it is not a fifteen-minute visit with a shop vacuum and a fogger. If someone offers that at a price that seems impossible, it is.

What it is, and when sealing rides along

Duct cleaning at Cook’s is negative-pressure cleaning: the system is sealed at the registers, a powered vacuum is connected at the trunk, and agitation tools work each run toward the vacuum so the debris leaves the house instead of settling somewhere else. The air handler cabinet, blower and coil are cleaned as part of the job, because a clean duct fed by a dirty blower is dirty again by fall.

In most Ocala houses built before 1990, sealing rides along. Joints are reconnected and sealed with mastic, not tape; the return plenum is sealed where it meets the air handler; boots are sealed to the ceiling or floor. Where a run is crushed, torn or undersized, we’ll quote replacement of that run rather than clean something that can’t do its job. Duct leak repair is one of the items Ocala Electric Utility pays a rebate toward with a licensed contractor’s receipt, so for city addresses the sealing line often comes partly back.

Commercial duct work, for restaurants on Market Street, medical offices on SR 200 and the I-75 distribution buildings north of town, runs the same way with larger equipment and a schedule built around the business’s hours.

The duct visit, register by register

1. The attic first. Before any cleaning, the technician goes up with a light and looks at every run, every joint and the plenum. In Ocala this is where the diagnosis gets made.
2. Airflow at each register, measured and written down. The starved back bedroom and the overfed hallway show up here.
3. The conversation. What’s leaking, what’s dirty, what’s crushed, and a price for each part of the fix before anything starts. Cleaning only, cleaning plus sealing, or replacement of specific runs.
4. Protection. Floors and furniture near registers covered.
5. Sealing and repair of the joints and plenum, if approved, done before cleaning so the vacuum isn’t pulling attic air through the gaps.
6. Negative-pressure cleaning, trunk to register, each run agitated and vacuumed in turn.
7. The air handler: blower wheel, cabinet, coil face and drain pan cleaned.
8. A new filter, and a look at whether the one-inch slot should become a media cabinet.
9. Airflow re-measured at each register, with the before-and-after on the report.

Schedule a duct inspection

Clearing the way: what to do before we arrive

A little preparation shortens the visit.

• Note which registers whistle and which rooms never cool; that steers the attic inspection.
• Clear a path to the attic access and to the air handler, whether it’s in the attic, the garage or a closet.
• Move furniture a couple of feet off floor registers and take anything fragile off shelves below ceiling supplies.
• Pull up your last twelve months of OEU, Duke, SECO or Clay Electric bills. The month-to-month shape helps us tell a duct problem from an equipment one.
• Mention if the house has had water in it. The June 2023 flooding and Milton’s rain in October 2024 reached ducts in some low-lying Marion County homes, and wet duct is a replacement conversation, not a cleaning.
• If pets or allergies are the reason for the call, say so. It changes the filter recommendation at the end.

The technician comes from Palm Coast, two hours west on SR 40, with the sealing materials and cleaning equipment on the truck. The price is set before the work and doesn’t change with the hour. The report you get afterward shows the before-and-after airflow at every register, and the next summer’s Ocala Electric bill shows the rest.