Real air ducts. Real results.

The questions below come straight from the calls and texts our dispatchers field every day from customers across Metro Detroit. They are written to help you make a good decision before you hire any air duct cleaning company — not just us.

The air duct cleaning industry in Southeast Michigan has more than its share of bad actors — arguably a worse ratio than any other home service. Search any Metro Detroit coupon mailer or social media marketplace and you will find the same ad over and over: "whole house air duct cleaning, $99, unlimited vents." That ad is not a deal. It is the front end of a bait-and-switch machine that the Better Business Bureau and the Federal Trade Commission have both written warnings about by name. The scam follows a pattern, and once you know the pattern, it is easy to avoid — which is exactly what this guide is for.

The single most useful credential in this trade is NADCA — the National Air Duct Cleaners Association — and its ACR standard, which spells out how a duct system is actually supposed to be cleaned: every supply, every return, the trunk lines, and the HVAC components themselves, using source removal under negative pressure, with verification that the system is visibly clean afterward. Michigan does not license duct cleaning as a standalone trade, so NADCA membership and technicians certified as Air Systems Cleaning Specialists are the closest thing to a meaningful credential the industry has. A company does not have to be a NADCA member to do honest work, but a company that follows the ACR standard can tell you exactly what that standard requires — and a company that has never heard of it is guessing with your ductwork.

The second filter is equipment, because the equipment defines what is physically possible. Real duct cleaning is done with negative pressure: a truck-mounted vacuum or a HEPA-filtered portable unit is connected to the trunk line and pulls the entire system into suction, while agitation tools — rotary brushes, air whips, compressed-air skippers — travel through each branch run and knock debris loose so the vacuum can carry it out. That is source removal, and it is the only method the ACR standard recognizes. The other thing sold as duct cleaning is a technician with a shop vac and a long brush attachment, reaching a few feet into each register. That removes what you could remove yourself with a Saturday afternoon and a vacuum, leaves the trunk lines untouched, and is what the $99 coupon actually buys. Ask every company you call one question: what vacuum unit do you use, and where does it connect? A real outfit answers in seconds.

The third filter is insurance. Proof of general liability and workers' compensation coverage separates a real company with real employees from a guy answering a lead-generation ad. A legitimate company produces a certificate of insurance on request, without drama, usually within the hour. It matters twice over: liability coverage protects your property if a job goes wrong — a cracked ceiling from an access cut, a damaged furnace panel, a punctured flex run — and workers' comp means a technician hurt in your attic or crawlspace is not your homeowner's policy's problem. BH Air Duct Cleaning Metro Detroit is Licensed & Insured, and we encourage you to ask us — and everyone else you call — for the paperwork.

The fourth filter is the quote itself. Honest duct cleaning pricing is bounded and quotable over the phone: for a typical Metro Detroit single-furnace home, a genuine whole-system cleaning runs roughly $350–$600 depending on the number of vents, the number of returns, and the condition of the system, with second furnaces and add-ons priced as disclosed line items. The quote should be written and itemized: how many supplies and returns are included, whether the trunk lines and the return side are cleaned (they are the dirtiest part of the system and the part shop-vac outfits skip), whether the blower compartment is included, what access holes will be cut and how they will be sealed, and what the total out-the-door number is. If a company cannot put the scope in writing before the truck rolls, the scope will be negotiated on your driveway — and you will not be the one winning that negotiation.

Now the anatomy of the $99 coupon, because it deserves its own paragraph. The math is simple: no legitimate company can send two technicians and a negative-pressure rig to your house for two to four hours for $99. The coupon exists to get a salesman inside. Once inside, the script begins: the $99 turns out to cover "one unit and ten vents," and your house — like every house — has more vents than that, at $25 to $50 each. Then the technician shines a flashlight into a return, photographs ordinary household dust at maximum zoom, and announces a problem. The $99 job leaves as a $900 to $1,800 invoice, and the actual cleaning performed is still the shop-vac version. The FTC has documented this exact sequence for years. The defense is simple: any advertised price dramatically below the honest market range is not a price, it is bait, and the correct response is to not schedule the appointment.

The most abusive branch of that script is the mold scare. The technician shows you a dark smudge inside a duct or on the blower housing, says the word "mold," and quotes a four-figure remediation on the spot. Here is what an honest company tells you instead: nobody can identify mold species by flashlight. Visible growth on a wet evaporator coil or drain pan is common and is fixed by cleaning the component and correcting the moisture source — not by fogging your ducts with mystery chemicals. If genuine widespread contamination is suspected, the honest move is a lab sample and, if confirmed, remediation under proper containment. A company that diagnoses mold in thirty seconds and cures it in an hour with a spray wand is running a script, not a service. No scare tactics is a company policy of ours, and it should be a hiring criterion of yours.

Sanitizer deserves the same scrutiny. Duct sanitizing — fogging an EPA-registered antimicrobial through the system — is a legitimate finishing step in specific situations: after confirmed microbial growth has been physically removed, after smoke or sewage events, or when odors persist after cleaning. It is legitimate only after physical source removal, because spraying disinfectant over dirt just gives you wet, chemically scented dirt. The scam version inverts this: the crew skips or shortcuts the cleaning, then sells a $200–$400 "sanitizing treatment" as the main event because fog is fast and margin is high. Ask two questions: what product, exactly (a real answer includes an EPA registration number), and is it applied before or after the mechanical cleaning? Wrong or vague answers to either one tell you what kind of company you are dealing with.

The fifth filter is photo documentation, and it is the single easiest way to verify you got what you paid for. Duct interiors are invisible to you, which is precisely why the honest end of this industry has standardized on before-and-after photos or camera-inspection footage of the trunk lines and representative branch runs — taken in your house, on that visit, not stock photos from a website. Ask on the phone whether documentation is included. A company that cleans systems properly is proud to show the difference; a company that objects to documenting its own work has told you why. We photograph every job, and we walk homeowners through the images before we leave.

The sixth filter is street presence and review pattern. Real duct cleaning companies have a base of operations that matches their service area, a long review history with photos, named technicians, and specific job details — "they showed me the trunk line camera footage in Livonia" reads very differently from "great service!!" five hundred times. Watch for the tells of a review-farmed profile: bursts of five-star reviews from accounts that have reviewed nothing else, a business address that resolves to a virtual office or a UPS store, and a phone number that routes to a national call center that books "appointments" and auctions your job to whoever is nearby. The work might still happen, but the accountability is gone the moment you have a complaint — the call center never touched your ducts and the subcontractor never gave you his real name.

Know what a real crew looks like on arrival, because the driveway is your last checkpoint. A legitimate duct cleaning visit is two technicians, a marked vehicle, and equipment that takes real effort to bring in: a vacuum unit connected to your trunk line near the furnace, long hoses, an air compressor, drop cloths, and corner guards for the hose runs. Setup alone takes twenty to thirty minutes, and a genuine whole-house cleaning on a single-furnace home takes two to four hours. If one person arrives in an unmarked minivan with a shop vac and is packing up ninety minutes later, you did not get a duct cleaning — regardless of what the invoice says. Real crews also protect the house: floors covered, registers removed carefully and reinstalled, access holes sealed with proper plates or plugs, and the furnace panels put back the way they were found.

Dryer vent cleaning belongs in this conversation because it is the one service with a genuine safety dimension, and because it bundles naturally with duct work. Lint-clogged dryer vents are a leading cause of house fires — that is a fire-marshal statistic, not a sales line — and the symptoms are mundane: clothes taking two cycles to dry, a hot laundry room, a burning smell. Honest standalone pricing in Metro Detroit runs $120–$200 depending on run length and roof versus wall termination, and most reputable companies discount it meaningfully when bundled with a duct cleaning since the crew and equipment are already on site. The upsell version to watch for is the reverse: a $99 duct coupon crew "discovering" a dryer vent emergency and pricing it like one. The fix is the same as everywhere else in this guide — get the number, in writing, before anyone touches anything.

Warranties and guarantees are the filter most customers forget to pin down. Duct cleaning has service guarantees exactly like any other trade: reputable companies stand behind the work with a written satisfaction guarantee — typically that if you find an area that was missed, they return and make it right at no charge — and they warrant any physical work like access-panel installation or duct sealing against workmanship failures for at least a year. Beware the inverted version: a "lifetime freshness guarantee" on a sanitizing fog is marketing vapor, because there is nothing to warranty. If a company cannot describe its guarantee in plain language, or if "all sales final" appears anywhere on the invoice, that is a tell. Real companies back their work because they expect to be in business in five years and expect to clean your system again in three to five of them.

For commercial customers a slightly different filter applies. You want a company that can produce a one-page proposal with the scope itemized to the ACR standard — air handlers by unit number, supply and return trunks by zone, VAV boxes, coil cleaning, containment and after-hours provisions — plus labor lines, warranty terms, and insurance certificates on company letterhead, signable as a purchase order. If your vendor cannot produce that document on request, they are a residential outfit stretching, and a medical office, restaurant, or light-industrial building needs a different vendor. The same company may be excellent at single-furnace colonials and unsuitable for a rooftop-unit portfolio; those are different skill levels, and the marketplace rewards specialization. We do both — and we are honest about the difference, and happy to recommend other reputable Metro Detroit companies for the rare job outside our wheelhouse.

Here is the condensed red-flag list, suitable for taping next to the phone. Advertised whole-house prices under $200. Per-vent pricing revealed only after arrival. No mention of negative-pressure equipment, or evasiveness when you ask what the vacuum connects to. Mold diagnosed by flashlight and cured by fog. Sanitizer sold as the main service instead of a finishing step. No written scope before the truck rolls. No before-and-after photos offered. No certificate of insurance available. A review profile that is all five stars from empty accounts. High-pressure "this price is only good today" tactics. Any one of these is a reason to slow down; two or more is a reason to hang up.

On the second opinion: if a crew in your house quotes a number that surprises you, you are allowed to send them away, pay only the disclosed trip or inspection fee, and call another company. Michigan consumer law does not require you to accept a quote just because the truck rolled, and it certainly does not require you to authorize work invented on your driveway. On a four-figure "mold remediation" diagnosis, a second opinion is worth paying for twice. Crews who refuse to leave without payment of the full inflated estimate are crossing into criminal territory; if it happens to you, the non-emergency police line will help, and a written complaint to the Michigan Attorney General's consumer protection division is exactly the mechanism that gets these operations shut down.

Honesty also requires saying when duct cleaning is not the answer, because a company that recommends it for everything is a sales organization. The genuine triggers: visible debris or pet hair blowing from registers, post-construction or renovation dust, a home purchase where the system's history is unknown, rodent or insect evidence in the ducts, smoke or water events, and heavy-shedding pets or allergy sufferers on a three-to-five-year cycle. What duct cleaning does not do is cure a dusty house by itself (most household dust is generated in the living space), fix airflow problems caused by undersized returns, or need repeating every year in a normal home. An honest company will sometimes tell you to save your money and change your filter more often. That answer, when you get it, is the strongest hiring signal in this entire guide.

On camera inspections: the borescope is the honest industry's favorite tool and the dishonest industry's favorite prop, and the difference is context. Used honestly, a camera run before the job documents actual conditions and scopes the work, and a run afterward proves the result — the same footage that anchors the photo documentation covered above. Used dishonestly, a zoomed-in frame of ordinary dust becomes a horror slide justifying a four-figure invoice. The tell is whether the company shows you the whole run or a single scary frame, and whether the footage comes with a measured recommendation or an on-the-spot ultimatum. Ask for the full video. Honest companies hand it over; the other kind changes the subject.

On maintenance and frequency: ductwork is not a filter and does not need annual cleaning, no matter what the postcard says. NADCA's guidance for a typical home is every three to five years, sooner with heavy-shedding pets, smokers, recent renovation, or allergy and asthma concerns — and dryer vents genuinely are an annual item. Between cleanings, the highest-value habits are boring: a quality filter changed on schedule, supply registers kept open (closing them raises static pressure and hurts the system), and a spring coil cleaning if your AC sweats through Michigan humidity. A company whose maintenance plan is built around those realities is a service organization; a company selling you an annual whole-house cleaning is optimizing for the invoice. Hire the first kind.

Worth mentioning one more time: we are Licensed & Insured. Our phone is (313) 236-4558. Our crews work Wayne, Oakland, and Macomb counties every day, every technician represents BH Air Duct Cleaning Metro Detroit directly — not a subcontractor booked through a call center — and every job gets a written scope up front and photos at the end. Whether or not you end up hiring us, we hope you take this guide with you. The next time you need duct or dryer vent work in Metro Detroit, ask the questions above. The trade has good people in it; you just have to know how to find them.

The duct cleaning trade has its own vocabulary and most of it never makes it onto the invoice in a form a homeowner can understand. Here is a short, opinionated glossary of the terms we use most often on the phone and on the truck. If you are calling around for a quote, knowing these terms will make every conversation shorter and every estimate easier to compare.

Supply ducts — the half of your duct system that delivers conditioned air to the rooms: warm air in winter, cool air in summer. Supplies terminate at the registers in your floors, walls, or ceilings, and they run under positive pressure whenever the blower is on. Because air is always pushing outward through them, supplies tend to stay somewhat cleaner than returns — which is why a quote that only covers "the vents" may be cleaning the cleaner half of your system and skipping the dirty half.

Return ducts — the other half: the ducts that pull air from the house back to the furnace to be filtered and reconditioned. Returns run under suction and inhale everything airborne in the living space — dust, pet hair, skin cells, carpet fiber — so they are consistently the dirtiest ductwork in any home. A real cleaning always includes the return side; a coupon cleaning almost never does. If you only remember one question from this glossary, ask whether the returns are included.

Trunk line — the large main duct, usually rectangular sheet metal running the length of the basement ceiling, that acts as the highway for the whole system. Every room's duct branches off the trunk. It is also where a negative-pressure vacuum connects during a proper cleaning, and where decades of debris settle by gravity. A crew that never touches your trunk line — never connects to it, never cuts an access opening in it — is not cleaning your duct system, whatever the invoice says.

Branch runs — the smaller ducts, round metal or flex, that split off the trunk line and carry air to each individual register. Branches are where agitation tools do their work during a cleaning: a whip or brush travels down each run from the register opening, driving debris back toward the trunk where the vacuum captures it. Long branch runs to far bedrooms are also the usual suspects when one room never gets comfortable.

Register vs. grille vs. diffuser — three words for the covers on your duct openings, and the distinction is practical. A register has an adjustable damper you can open and close; a grille is a fixed cover with no damper, standard on returns; a diffuser is the ceiling fitting that spreads air in a pattern, common in newer builds. Techs use the words interchangeably on the phone, but on an itemized quote the count of supplies and returns is what drives the price — so count your covers before you call.

Boot — the sheet-metal transition fitting that connects the end of a branch run to the register opening in your floor or wall. Boots are where debris, pet toys, construction screws, and the occasional LEGO collect, and floor boots in particular act as open trash bins for whatever gets kicked in. Boots are also a common leak point: an unsealed gap between the boot and the floor cut pulls dusty joist-cavity air into your airflow. Cheap to seal, worth asking about.

Plenum — the sheet-metal box attached directly to the furnace where air is collected and distributed: the supply plenum sits above the furnace and feeds the trunk, and the return plenum (or return drop) delivers incoming air to the filter and blower. Plenums are the crossroads of the system, they see every particle that moves through the house, and they are one of the first places a camera inspection looks to judge how dirty a system really is.

Air handler — the umbrella term for the indoor unit that moves the air: in most Metro Detroit homes that is the furnace itself, whose blower serves both heating and cooling. The air handler contains the blower wheel, the motor, and the control board, with the evaporator coil mounted alongside or above. When a duct cleaning quote says it includes "the air handler," pin down what that means — a proper job opens the blower compartment and cleans it, rather than treating the furnace as a sealed box between two clean ducts.

Blower wheel — the squirrel-cage fan inside the air handler that actually moves every cubic foot of air in your house. Its dozens of small curved fins load up with fine dust, and a blower wheel caked with even a sixteenth of an inch of buildup can lose a fifth or more of its airflow while making the motor work harder and run hotter. Cleaning it is a component job — the wheel is accessed or pulled and washed — and it is one of the highest-value line items in HVAC cleaning, because you feel the airflow difference the same day.

Evaporator coil — the A-shaped refrigerant coil above the furnace that cools your air in summer. It runs cold and wet, which makes its densely packed fins a magnet for dust and, left long enough, a happy home for microbial growth — the source of that musty smell when the AC kicks on. A dirty coil also chokes airflow and can ice over into a solid block. Coil cleaning is a legitimate, separately priced service; just confirm the coil is being physically cleaned, not merely sprayed with deodorizer.

Heat exchanger — the sealed steel chambers inside the furnace where combustion happens: burner exhaust stays inside the exchanger while household air passes over the outside and picks up heat. The two air streams must never mix — a cracked heat exchanger can leak carbon monoxide into the airflow, which is a furnace-replacement conversation, not a cleaning one. Duct cleaners work around the exchanger, not inside it; a crew that claims to "clean your heat exchanger" as a line item deserves follow-up questions.

Flex duct — the wire-coil, plastic-and-insulation duct that looks like a giant dryer hose, common in newer builds, attics, and finished-basement retrofits. Flex works fine when stretched taut and properly supported, and poorly when kinked, crushed, or sagging. It also demands gentler cleaning: aggressive rotary brushes can tear the inner liner, so a competent crew switches to air-driven tools on flex runs. If your home has flex, ask the company how they clean it — the answer tells you whether they have thought about it.

Duct liner — fiberglass insulation bonded to the inside of some ducts, mostly for sound-deadening near the air handler and in commercial systems. Lined duct cannot be cleaned like bare metal: hard brushes shred the liner and send fibers into the airstream, so the ACR standard prescribes soft-bristle, non-aggressive methods for it. Liner that is wet, moldy, or deteriorating cannot be cleaned back to health at all — it gets replaced or the duct gets relined. A crew should identify liner before quoting, not discover it mid-job.

Negative pressure / source removal — the method that defines legitimate duct cleaning. A high-powered vacuum connects to the trunk line and puts the entire duct system under suction (negative pressure), so nothing escapes into the house; agitation tools then work through every branch driving debris toward the vacuum, which physically removes it from the system. That combination — agitate and extract — is source removal, and it is the only method NADCA recognizes. Everything else — fogging, spraying, vacuuming a few feet into each register — leaves the source in place.

HEPA filtration — High-Efficiency Particulate Air: a filter class that captures 99.97% of particles at 0.3 microns. On a duct job it matters most on portable vacuum units that exhaust inside your home — HEPA filtration means the fine dust pulled out of your ducts stays in the machine instead of recirculating into your living room. Truck-mounted units sidestep the issue by exhausting outdoors. Either is fine; a portable unit without HEPA is not.

Rotary brush — a spinning brush head on a flexible cable shaft, driven by a drill or dedicated motor, fed down each duct run to scrub the walls while the vacuum pulls the loosened debris away. Rotary brushes excel on bare sheet metal and on caked-on buildup, and a good crew carries multiple head sizes to match round branch runs and rectangular trunk. Their limitation is the reason crews carry air tools too: brushes are too aggressive for flex duct and lined duct.

Air whip — a compressed-air tool with several flexible rubber tentacles that thrash rapidly inside the duct, beating debris off the walls and driving it toward the vacuum. Whips shine exactly where brushes struggle — flex duct, lined duct, and lightweight debris like pet hair and drywall dust — because they agitate hard without abrading the surface. The sound of a whip working through a duct run is unmistakable; hearing it during your job is a good sign the crew is doing real agitation.

Air skipper — a compressed-air nozzle with rear-facing jets that propel it forward through the duct on its own, "skipping" along while blasting debris back toward the vacuum connection. Skippers are the tool of choice for long branch runs and tight turns that a brush shaft cannot negotiate. Real crews use brushes, whips, and skippers in combination, matching the tool to each run — which is why "what tools do you run through the ducts?" is such an effective screening question on the phone.

Access panel — the openings a crew cuts into the trunk line and plenum to connect the vacuum and feed agitation tools, since duct systems are not built with cleaning doors. The professional standard is to close every opening with a proper sheet-metal patch, a reusable access door, or a rated plug — sealed airtight. Duct tape over a raw hole is not a closure, and the state of the access points after the crew leaves is one of the easiest ways to judge the quality of the whole job.

MERV rating — Minimum Efficiency Reporting Value, the 1–20 scale for how well a filter captures particles. Cheap fiberglass pads are MERV 1–4 and mostly protect the equipment; MERV 8–11 is the practical sweet spot for most Metro Detroit homes; MERV 13 captures smoke and finer allergens but breathes harder. The catch: a filter more restrictive than your blower can handle raises static pressure and hurts airflow. Higher is not automatically better — matched to the system is better.

Static pressure — the resistance the blower pushes against to move air through the system, measured in inches of water column; think of it as the duct system's blood pressure. Dirty coils, clogged filters, crushed flex, and closed registers all raise it, and high static pressure means less airflow, more noise, and a motor working toward an early grave. It is also why closing registers in unused rooms — the classic homeowner "efficiency" move — usually backfires.

CFM / airflow — cubic feet per minute, the measure of how much air the system actually moves. A typical residential furnace is designed for roughly 400 CFM per ton of cooling, and everything in this glossary — duct sizing, filter choice, coil condition, blower cleanliness — ultimately cashes out in CFM. When a room is always stuffy or cold, the question is almost never "is the thermostat broken" and almost always "where did the CFM go."

Anemometer — the handheld instrument that measures air velocity at a register, from which airflow is calculated. It turns "the airflow seems better" into a before-and-after number, which is why quality-minded crews carry one and take readings at problem registers before and after cleaning. You do not need to know how to use one — you just want to hire the kind of company that does.

Antimicrobial fogging — applying an EPA-registered antimicrobial as a mist through the duct system to treat surfaces after microbial growth has been physically removed. Done right, it is a finishing step with a specific product, a registration number you can look up, and a label that permits use in HVAC systems. Done wrong, it is the whole service — fog sprayed over dirt as a substitute for cleaning — and that version is the single most common upsell scam in this industry. Fogging comes after source removal or it is theater.

Puff-back — a misfire in an oil (or occasionally gas) furnace that blasts soot through the duct system and out every register, coating walls, ceilings, and furniture in oily black film. Puff-backs are one of the unambiguous cases where full duct cleaning is not optional — the ducts are loaded with soot that will keep resurfacing until it is physically removed — and the event is typically covered by homeowner's insurance. If it happens, document everything before cleanup starts.

Duct sealing / mastic / foil tape — closing the leaks where ducts spill air into basements, walls, and attics; a typical older home loses 20–30% of its conditioned air this way. Mastic is the paint-on sealant that hardens into a permanent seal, and UL-181 foil tape is the rated tape for joints and seams. The cloth "duct tape" in your junk drawer is, famously, the one thing you should never use on ducts — its adhesive dries out and fails in a couple of seasons. Sealing pairs naturally with cleaning, since access is already open.

Dryer vent termination hood — the exterior fitting where your dryer duct exits the house, with a flap or louvers that open under dryer airflow and close against weather and pests. A lint-caked hood whose flap no longer swings freely chokes the whole vent run, and in Michigan a stuck-open flap is a standing invitation to birds and mice come fall. Walk outside while your dryer runs: if you cannot feel strong, warm airflow at the hood, the run needs cleaning.

Booster fan — an inline fan added to a duct run to push air farther than the blower alone can manage — on the supply side for a far room that never gets comfortable, or on a long dryer vent run (generally anything much past 25 equivalent feet) to keep lint moving. The honest caveat: a booster is sometimes a patch over an undersized or leaky duct, and a good company checks for the underlying problem before selling you a fan bolted on top of it.

Lint trap vs. dryer vent — the distinction behind most dryer-fire complacency. The lint screen you clean before every load catches maybe 60–75% of the lint; the rest travels into the vent duct behind the machine and builds up along the full run to the termination hood, where you never see it. "I clean the lint trap every time" and "my dryer vent is clean" are two different claims. The vent run is the one that causes fires, and it is an annual professional cleaning item, typically $120–$200 in Metro Detroit.

NADCA ACR standard — the industry specification, published by the National Air Duct Cleaners Association, that defines what a real duct cleaning includes: every supply, every return, the trunks and plenums, and the HVAC components, cleaned by source removal under negative pressure, with the result verifiable by inspection. It is the document that separates duct cleaning from duct dusting. You do not need to read it — you just need to ask a company whether they clean to it, and listen to whether the answer sounds like recognition or improvisation.

IAQ — indoor air quality, the umbrella term for everything you breathe inside: dust, pollen, pet dander, humidity, VOCs, combustion byproducts. Duct cleaning is one honest piece of the IAQ picture — it removes the debris load the system recirculates — alongside filtration, humidity control, and ventilation. Be wary of anyone selling duct cleaning as an IAQ cure-all, and equally wary of gadget-heavy "IAQ packages" sold by fog and flashlight. Clean system, good filter, sane humidity: that is most of the battle.

That is the vocabulary that covers ninety-five percent of the conversations we have with Metro Detroit homeowners. If a technician in your basement uses a term that is not on this list and cannot explain it in plain language when you ask — ask harder. Good techs love explaining this stuff. It is half the reason we wrote this page.