12 Questions to Ask Before Hiring Any Duct Cleaning Company
Every duct cleaning company sounds the same on the phone: licensed, professional, great reviews, free estimate. The differences only show up when you ask specific questions — and the bait-and-switch operators are counting on you not asking any. The twelve questions below take about five minutes and filter out most bad actors before anyone sets foot in your home. Our own answers are included under each one, but the checklist protects you no matter who you call, in Pennsylvania or anywhere else.
1. Are you licensed and insured — and can you prove it?
The answer you want is a registration number you can look up and a certificate of insurance they will send before the appointment. In Pennsylvania, home improvement contractors must register with the state, and the Attorney General's office keeps a searchable public database — a real company hands over its number without a pause. Insurance matters just as much: technicians will be opening up your HVAC system and working through basements, closets, and attics, and if an uninsured crew damages something, the bill lands on you.
Our answer: PA registered contractor PA 187935, insured up to $2 million, and we will send proof of both before we arrive.
2. Will you give me a flat, written quote before any work begins?
The answer you want is an unconditional yes. An honest company looks at the job, puts one all-inclusive number on paper, and lets you decide before a single tool comes out — because that number is not going to change once the crew is inside. A company that will only commit to a starting price, or that keeps the final figure open until the work is underway, is leaving itself room to improvise in your hallway. That is the mechanic behind the $49–$99 "whole house special" — the teaser price gets a foot in the door, and the upsells start at the first register. We broke down exactly how that pitch works in our guide to the $49 duct cleaning special.
Our answer: every air duct cleaning starts with a free video inspection, and you get a flat, written quote before any work begins — no trip fees anywhere in our service area, and the number on the quote is the number on the invoice.
3. What cleaning method do you use?
The answer should be source removal: mechanical agitation — air whips and brushes — that breaks buildup loose from the duct walls, combined with a negative-pressure vacuum that pulls everything into a sealed, filtered collection unit. That is the approach the NADCA industry standard describes, and it is the difference between removing the dust and rearranging it. If the person on the phone cannot name a method, or describes something that amounts to holding a vacuum near the register openings, keep calling. Our explainer on source-removal duct cleaning covers how the process works step by step.
4. What equipment will you bring into my home?
Method and equipment are two sides of the same question. Source removal requires a negative-air machine with HEPA filtration, compressed-air agitation tools, and register sealing — a kit that fills a van, not a trunk. Ask what machine they run and how the debris is collected. "A powerful vacuum" is not an answer; a shop vac and a compressor wand cannot hold a whole duct system under suction.
Our answer: professional Nikro negative-pressure machines with HEPA filtration, plus air whips and agitation tools for every run — the same setup you can see on our process page.
5. Will you show me the inside of my ducts before and after?
The inside of a duct is the one part of the job you cannot inspect from the hallway, so proof policy matters more here than in almost any other home service. Ask two things: do they inspect and show you the condition before quoting any extra work, and do they document the results when they finish. A company confident in its work volunteers the evidence; a company that resists showing you your own ductwork is asking you to pay for something invisible on faith.
Our answer: a free video inspection inside your ducts before any work begins, and after-photos when the job is done — on every job, not on request.
6. What exactly does the price include?
Get the scope in plain words: every supply run, every return, the trunk lines, and the registers. Per-vent pricing is where "specials" hide their real cost — the advertised number covers a handful of supply vents, and the returns, the trunk, and the second system each turn out to be extra. Ask directly: "Is there any part of my duct system your price does not cover?" and listen for hedging.
Our answer: your written quote covers the complete system — supplies, returns, trunk lines, and registers. Add-ons like sanitization exist, but they are optional, quoted in writing before you approve anything, and only recommended when the camera shows a reason.
7. How long will the job take?
A real single-system cleaning takes several hours. The crew has to seal registers, connect the vacuum to the trunk, and agitate every run individually — there is no honest way to compress that into 45 minutes. Ask for the expected time on site and treat a very short answer as a scope admission: a crew that plans to be gone within the hour is planning to clean the first few feet behind each register. Our guide to how long duct cleaning takes breaks the visit down stage by stage.
8. Do you back the work with a guarantee?
Ask what happens if you are not satisfied — and who enforces it. A verbal "we stand behind our work" is worth exactly what it costs to say. Look for a written guarantee, and for third-party backing that does not depend on the company's goodwill. Google Guaranteed status, for instance, is verified by Google and carries money-back protection on qualifying jobs — the company cannot award it to itself.
Our answer: E Cleaning is Google Guaranteed, with money-back protection up to $2,000 on qualifying jobs, on top of our own commitment to make the job right.
9. Can I verify your reviews?
Reviews are easy to fake on a company's own website and much harder to fake on a Google Business Profile tied to a verified address. Check the profile, not the testimonial page: does the company have a real location, a review history that spans years rather than one enthusiastic month, and responses to its negative reviews? Read the worst reviews first — how a company handles an unhappy customer tells you more than fifty top-rated ratings. And make sure the business name on the reviews matches the name on the license and the truck; lead-generation operations often run several interchangeable brand names through one dispatcher.
10. Who is actually coming to my house?
Ask whether the technicians are the company's own people or subcontractors dispatched through a call center. National lead-generation outfits sell your job to whoever buys the zip code, which means the company you researched is not the company that shows up — and the crew's first incentive is to recover the lead fee through upsells. A local company can tell you who is coming, and the name on the van matches the name on the invoice.
Our answer: E Cleaning is family-owned and has run its own crews from King of Prussia since 2016. The people in your basement work for us, not for a lead broker.
11. What happens if you find mold, pests, or damage?
This is where scare-tactic operations make their real money, so pin the policy down in advance: if the crew finds a problem, do you get evidence, a written price, and time to decide? An instant "black mold" diagnosis in the first ten minutes, a sudden four-figure remediation quote, and pressure to approve it on the spot is a script, not a service. Genuine findings survive scrutiny — they can be photographed, explained, and quoted in writing. Our article on mold in air ducts covers what a legitimate response looks like.
Our answer: anything we find goes on camera before we say a word about price. Sanitization uses EPA-registered products, is recommended only when the video shows a reason, and is quoted in writing — and you can always decline.
12. Do you handle dryer vents too — and what do you charge?
A duct crew is already on site with the right tools, so a combined visit should be easy to price. The question also doubles as one more pricing test: a company that will put a clear dryer vent price in writing up front is a company used to charging everyone the same. And it is worth adding while the crew is there, because the dryer vent is the line with the fire risk attached.
Our answer: yes — dryer vent cleaning gets the same treatment as everything else we do: a flat, written quote up front, easy to add while the crew is already on site. Our dryer vent fire safety guide explains why that line deserves the same attention as the ducts.
What do good and bad answers sound like?
You do not need to memorize scripts — the pattern repeats across every question. Good answers are specific, verifiable, and boring. Bad answers are vague, urgent, or conditional on the crew "taking a look first."
| You asked about | A good answer | A red flag |
|---|---|---|
| License & insurance | A number you can look up; certificate sent before the visit | "We're fully licensed" with nothing to verify |
| Price | A flat, written quote before any work begins | $49–$99 teaser, or a price that keeps moving once work starts |
| Method | Source removal: agitation plus negative-pressure collection | Cannot name a method, or "we vacuum the vents" |
| Equipment | Negative-air machine with HEPA filtration, agitation tools | "A powerful vacuum" |
| Proof | Inspection before, photos after, on every job | "You'll be able to feel the difference" |
| Time on site | Several hours for a single system | "We'll be in and out within the hour" |
| Guarantee | Written terms, third-party backing | "We stand behind our work," nothing on paper |
What does the full checklist look like?
Here are all twelve questions in one place — screenshot this and work down the list on your next call:
- Are you licensed and insured, and can you send proof?
- Will you give me a flat, written quote before any work begins?
- What cleaning method do you use?
- What equipment will you bring into my home?
- Will you show me the inside of my ducts before and after?
- What exactly does the price include?
- How long will the job take?
- Do you back the work with a written guarantee?
- Can I verify your reviews on an independent platform?
- Who is actually coming to my house — employees or subcontractors?
- What happens if you find mold, pests, or damage?
- Do you handle dryer vents too, and what do you charge?
A single stumble is not automatically disqualifying — but a company that stumbles on three or four of these is telling you how the visit will go. The pattern to reward is simple: flat written quotes, named methods, verifiable credentials, and proof you can see with your own eyes. If you want to know what a visit looks like when a company can answer all twelve, our walkthrough of what to expect during your appointment covers it hour by hour.
E Cleaning has served Montgomery, Chester, Bucks, and Delaware counties from King of Prussia since 2016 — and every answer above is the one you will get when you call.
Want the printable one-page version? Get the checklist here.>