**Short answer:** a proper residential duct cleaning takes three to five hours, uses negative pressure to pull debris out of the system rather than pushing it around, and covers the full network — supply runs, return runs, registers, and the air handler. Crews move through the house room by room. You don't need to leave. Most people have never watched a duct cleaning happen. That's part of why the industry has a reputation problem: when you can't see the work, it's hard to know whether you got any. This is what a real job looks like, start to finish. ## Before anyone touches a duct **Walkthrough and system inspection.** The technician finds your air handler, locates every supply and return register, and identifies what kind of ductwork you have — sheet metal, flex, fiberglass duct board, or some combination. In older homes across the Pioneer Valley, it's frequently a combination, and that changes the approach. **Assessment.** This is where an honest contractor sometimes tells you that you don't need the service. Light dust on the registers of a system cleaned four years ago is not a reason to spend money. Visible debris, microbial growth, evidence of rodent or insect activity, or post-renovation construction dust are. **Protection.** Drop cloths at the air handler and at work areas. Corner guards on hose runs if needed. You should be walked through what was found before work starts, not handed a surprise at the end. ## The core of the job: negative pressure Here's the part that separates a real cleaning from a theatrical one. A large vacuum unit — either a truck-mounted system or a portable HEPA-filtered unit — connects directly to your trunk line, usually near the air handler. It's switched on and the entire duct system is placed under negative pressure. Everything dislodged inside the ducts travels toward that collection point and out of your house. This is what NADCA calls *source removal*, and it's the standard the whole trade is measured against. Without it, agitating debris inside a duct just relocates it. If someone shows up with a shop vac and a brush and cleans only what's reachable from each register opening, you're getting the vent covers cleaned. The ducts themselves — the runs behind the walls, the trunk, the returns — are untouched. ## Room by room With the system under negative pressure, the crew works the house systematically. **At each supply register:** the grille comes off. An agitation tool goes into the duct — compressed-air whips, rotary brushes, or air skipper nozzles depending on the duct material. Flex duct and fiberglass duct board can't take an aggressive rotary brush without damage, which is why material identification at the start matters. The tool breaks debris loose and the vacuum carries it away. **At each return:** returns are usually dirtier than supplies, sometimes dramatically so. They're pulling air from the house — dust, dander, hair, whatever's on the floor. In many homes the return side accounts for most of what comes out. **Registers and grilles:** cleaned individually, not just wiped at the face. **The air handler itself:** blower assembly, blower wheel, evaporator coil, drain pan, and interior cabinet. The blower wheel is worth paying attention to. Buildup on the fins measurably reduces airflow, and a lot of "my system doesn't move air like it used to" complaints trace back to exactly that. **Filter:** replaced or, if it's a washable type, cleaned. ## How long it takes For a typical single-family home in Western Mass or Northern Connecticut, plan on three to five hours. The variables: - Number of registers and returns - Square footage and number of zones - Duct material and accessibility - How much is actually in there - Whether the air handler is in a tight crawlspace or attic A crew that quotes you ninety minutes for a full residential system is not doing a full residential system. ## What you should get at the end **A walkthrough of the results.** Before-and-after photos of the interior of the ductwork are standard practice for reputable contractors. Ask for them. You can't inspect the inside of a duct run yourself, and photos are the only honest verification available. **Everything put back.** Registers reinstalled, access panels sealed, work areas cleaned. **A clear description of what was done** — which components, what method, what was found. **Straight talk about anything discovered.** Disconnected duct runs, crushed flex, unsealed joints, moisture problems, or signs of pest activity are common findings, and they're separate issues from cleaning. A good contractor tells you what they saw and what it means, without turning it into a high-pressure upsell. ## Questions worth asking before you book - **Are you NADCA-certified?** You can verify membership directly through NADCA rather than taking anyone's word for it. - **Do you have an ASCS on staff?** Air Systems Cleaning Specialist is the individual credential. - **What's included?** Specifically: are the returns and the air handler in the price, or are those add-ons? - **What equipment are you using?** You're listening for truck-mounted or HEPA-filtered portable with negative pressure — not a shop vac. - **Do you provide before-and-after photos?** - **Is the quote for the whole system?** Per-vent pricing that balloons on the day of service is the oldest complaint in this trade. ## Do you need to be home? Yes, at least for the walkthrough at the start and the review at the end. In between, the crew needs access to every register and the air handler, so someone should be there. You don't need to leave the house — the negative pressure setup means debris exits through the hose, not into your living space. ## The honest version Duct cleaning isn't magic and it isn't necessary every year. What it does is remove accumulated debris from a system that circulates air through every room you live in. Whether that's worth doing right now depends on what's actually in your ducts. We're NADCA-certified and serve Western Massachusetts and Northern Connecticut. If you're not sure where your system stands, we'll tell you honestly — including when the answer is that it can wait.