Ductwork & Duct Cleaning

It works at what it is for, which is removing material from inside the duct. After a renovation, after mice or water, or on a system that ran for years with the filter slot empty, a proper source-removal cleaning makes a visible difference. What it does not do is improve airflow, fix a hot room, lower a bill or cure allergies. Those are sealing, sizing and air quality questions. If someone quotes cleaning as the answer to a comfort complaint, ask what they measured.

On an event basis, not a schedule. No interval applies to every house, and the annual-cleaning pitch exists because a recurring service sells better than a one-off. Clean after construction dust, after a pest or moisture problem, when buying a house whose history you do not know, or when you can see debris at the register. Otherwise a well-filtered system stays reasonably clean.

It follows the number of supply and return openings, how accessible the trunk is, whether the system is one air handler or three, and whether anything needs opening up to reach. A walk-out basement with a straight trunk is a different job from a finished attic with flex through the rafters. Be careful with a headline price that covers unlimited vents — that is usually a rod-and-vacuum pass at the boot, not a cleaning of the system.

Sealing closes the leaks at joints, seams, boots and plenums with mastic so conditioned air arrives in the room instead of in a crawlspace. It is worth doing when ducts run outside the heated envelope — an attic, a vented crawl, a garage ceiling — which describes a great many houses in this region. It is the single cheapest way to make an existing system perform better, and it is worth doing before, not after, a system replacement.

Work backwards from the register. Weak air at the vent means the branch is undersized, kinked, disconnected or leaking before it arrives. Good air but the wrong temperature means the room is losing or gaining heat faster than that branch can keep up — a west-facing addition, a room over a garage, a finished attic. The first is ductwork repair. The second is zoning, a dedicated ductless head, or insulation. Closing vents elsewhere is not a fix; it raises pressure and makes the leaks worse.

Motorised dampers in the trunk open and close under a zone controller, with a thermostat per zone, so the system sends air where there is a call instead of everywhere at once. It works well on a variable-speed system whose blower can back down when only one zone is open. On a single-stage system with a tight duct trunk it forces full airflow through a fraction of the duct, which is loud and hard on the equipment. We check the trunk capacity before quoting zoning, and sometimes recommend a ductless head instead.

Sometimes, and you should find out before you order equipment rather than after. Modern high-efficiency systems move more air across a larger coil than the equipment they replace, and ducts sized decades ago for a smaller, hotter system frequently cannot carry it. We measure static pressure on the existing system first. Often the answer is modifications — a bigger return, a new plenum, a couple of reworked branches — rather than a full replacement.

Yes, and access drives the work. In a finished attic we look for an existing hatch, a soffit or a closet chase before opening drywall, and we tell you in advance where we would need to. In a crawlspace the usual finds are flex off its collar and insulation slumped off a supply run. Both are straightforward once someone gets in there.