Duct Leakage Testing Without the Runaround.
Every duct conversation eventually needs a number: how much does this system actually lose? Leakage testing produces it, the network pressurized, the escape rate measured, the losses quantified in cubic feet and dollars, converting suspicion into scope and making every sealing and replacement decision an arithmetic problem instead of an argument.
Ductwork · Burnet & Central Texas
The Number That Settles Arguments
The test is elegant physics: the duct system gets sealed at its registers and pressurized by calibrated fan, the airflow required to hold test pressure equaling what escapes through the network’s cumulative leaks, read in CFM and expressed against system airflow as the percentage that tells the story, tight systems holding single digits, the Texas fleet’s untested reality routinely measuring twenty to thirty-plus, a quarter of conditioning capacity delivered to attics and wall cavities on every runtime hour. The number converts directly: leakage percentage against your equipment’s output and your utility rates yields the annual dollar tax, the figure that sizes sealing projects honestly and occasionally justifies replacement verdicts, arithmetic where the industry usually offers adjectives.
Testing engagements arrive from every direction: the diagnostic entry, symptoms, dusty houses, weak registers, comfortable attics, bills outrunning usage, earning quantification before any fix gets scoped; the sealing project’s bookends, before establishing baseline and scope, after proving the mastic’s work, closure demonstrated rather than asserted; the code and program contexts, new construction verification where jurisdictions require it, energy-program documentation, real-estate due diligence on the county’s larger transactions; and the equipment-decision support, replacement quotes deserving the duct number first, since new equipment inherits the network’s honesty or its lies. Every test files its numbers, baseline, conditions, results, the system’s leakage history joining its permanent record.
The pairing discipline holds here as everywhere: testing serves decisions, and the test that finds losses feeds the sealing arithmetic on its own page, scope sized to measured escape, the after-test closing the loop, tax cancelled and proven.
Local conditions shape this work more than most homeowners expect. Our summers stack week after week of hundred-degree afternoons, which means long compressor runtimes, drain lines moving gallons of condensate a day, and electrical components living near their limits from June through September. Lake humidity keeps the corrosion clock running even in mild months, and spring pollen packs filters fast enough to choke airflow in weeks. A tech who works this exact hundred miles every day builds all of that into the leakage testing call: what to check first, which parts fail early here, and which settings survive a Texas cooling season instead of merely a laboratory one.
Ductwork
What the Test Delivers
The engagement’s concrete products, beyond the number itself.
The leakage rate, measured
CFM escaping at test pressure, the network’s honesty expressed as a percentage of system airflow.
The dollar conversion
Losses against your equipment and rates, the annual tax the leaks collect, stated plainly.
Supply-return breakdown
Which side leaks worse, the comfort-tax supply or the air-quality-tax return, testing isolates both.
Escape-route reconnaissance
Pressurization’s diagnostic side, smoke and detection walking the biggest leaks while the system holds pressure.
Scope for the fix
The sealing project sized to measured reality, or the replacement conversation triggered by terminal numbers.
Documentation that counts
Code compliance, program credits, transaction due diligence, and your file’s permanent baseline.
Skip the reading, make the call.
Two minutes on the phone with a real tech beats an hour of internet research. Describe the symptom in your own words and get a straight answer about cause, timing, and cost.
Why Off Duty
Before Money Moves, Measure
The testing discipline’s core argument is sequence: air quality budgets aimed at dust problems that are really return leaks, equipment upgrades bolted to networks losing a quarter of their delivery, sealing projects scoped by guess in both directions, too timid to harvest the real losses or too sweeping for the actual need, every one of these spends better behind a measurement, the test’s modest cost buying aim for dollars that dwarf it. The corridor’s classic sequence error, five-figure equipment replacing four-figure symptoms of a three-figure duct problem, keeps the case current, and our assessment habit of leading with numbers, static pressure, register flows, leakage where indicated, exists because measured houses buy the right fixes in the right order, the file accumulating the arithmetic that keeps every subsequent decision honest.
For the building-performance minded, testing joins its siblings, blower-door envelope numbers, register flow verification, static pressure profiles, in the whole-house diagnostic picture, and for everyone else it stays the simple product this page promises: the number, its dollar meaning, and the scoped path to canceling it. Texas duct systems built through the boom decades test badly as a fleet; yours is probably average, which is the problem; and the test is how probably becomes a number with a fix attached.
Here is how the visit goes. A call to (512) 925-3090 reaches a real tech, not a call center, at any hour. On site, the diagnosis runs on instruments until the cause is certain, and then everything gets laid out in plain English: what failed, what fixes it, and exactly what it costs, before work begins. When the leakage testing work is done, it gets verified under load instead of switched on and waved at. If the pattern sounds simple, it is. It is also rare enough in this trade that people write reviews about it.
A straight word on money. We do not print teaser prices on this website and we do not do surprise math on invoices. Call, describe the problem, and we will tell you what the visit costs before a truck rolls. When the diagnosis is in, you get the full repair price out loud, before the work starts, and you decide with the real number in front of you.
Worth saying plainly: this is not a problem that ages well. Systems compensate quietly right up until they cannot, and the failure that finally announces itself usually costs more than the one caught early would have. If your gut says something is off, that instinct is worth one free phone call. The worst case is we tell you everything sounds normal, which is a pretty good worst case.
Who does the work matters as much as what gets done. Off Duty is owner-operated: the person diagnosing your system is the person whose name carries the company, trained in the family trade and seasoned by ten years of Central Texas installs and repairs. You can see the standard in real job photos, and you will see it again in your own equipment closet.
Coverage is the same as everything else we do: Burnet at the center, about 100 miles in every direction. That means the lake towns, Marble Falls, Kingsland, Horseshoe Bay, the corridor through Leander, Cedar Park, and Georgetown, plus Austin, Bell County, and the outer ring through Waco, San Marcos, New Braunfels, Fredericksburg, and Boerne. The full sixteen-county list lives on the service areas page, and if you sit just past the edge of it, call anyway and get an honest answer.
Diamond Contractor
Mitsubishi’s top ductless credential, earned with factory training.
Second Generation
Raised in the trade, ten years on the tools before the name went on a truck.
Warranty Authorized
JB and Mitsubishi warranty work: we file the claim, you skip the fight.
Open 24 Hours
A real person answers the phone at any hour, every day of the year.
The Standard
How This Work Gets Done Here
A job like this is a chain of small decisions nobody watches: which part, which setting, which clearance, which step gets skipped when the attic hits 130 degrees. Our answer to all of them is the same. Do it the way the book says, the way the second generation was taught, the way you would want it done if the address were your own. That means proven diagnosis before parts, correct materials over convenient ones, and procedure followed all the way through the parts of the job that never show.
It also means finishing properly. The system gets verified under working load, the readings get documented, the old components get shown on request, and you get an explanation in plain English rather than trade jargon. The price never moves between the quote and the invoice. If anything about the work ever needs a second look, the phone number on your receipt rings the person who did it. Simple system, kept promises, reviewed in public by the people it was kept to.
Duct Leakage Testing Questions
Asked Before We Roll a Truck
Real questions from real Central Texas customers, answered the same way we answer them on the phone: straight.
How does the duct leakage test actually work?
The system’s registers get sealed with test coverings, a calibrated fan connects at a central point, typically the return or air handler, and pressurizes the network to the standard test pressure, and the fan’s airflow required to maintain that pressure equals the network’s total escape rate, since what the fan supplies, the leaks are losing, read in CFM and expressed against your system’s rated airflow as the leakage percentage. The engagement runs about an hour for most homes, non-invasive throughout, and includes the diagnostic reconnaissance while pressure holds, the biggest escape routes walked with detection so the number arrives with its map. Physics, calibration, and patience, producing the figure every duct decision deserves.
What is a good leakage number, and what is bad?
The scale runs from engineered to archaeological: new-construction standards target single digits, tight existing systems hold under ten percent, the fleet’s honest middle spreads through the teens, and the untested Texas stock routinely measures twenty to thirty-plus, the born-leaky boom construction and its decades of attic entropy, with the dollar meaning scaling alongside, each point of leakage a point of your conditioning spend delivered to the attic. Context tunes the verdict, duct location, system size, the house’s goals, but the working thresholds hold: under ten, maintain; teens, sealing arithmetic usually pays; twenties-plus, sealing strongly indicated with the replacement question opening where structure convicts alongside. Your number lands on this scale the day of the test.
Is testing required for new construction here?
Increasingly: Texas energy code requires duct leakage verification on new residential construction, tested by approved methods at rough-in or final, documented to thresholds, with local enforcement varying across the sixteen-county spread but tightening in the corridor jurisdictions, and builders needing tested-and-documented systems as standard practice, a service we provide on construction calendars, rough-in tests catching problems while correction is cheap, finals delivering the compliance paperwork. Beyond code, the energy programs and their credits ride on the same numbers, and the custom-build clientele increasingly demands the verification regardless of mandate, engineered air per the design page deserving proven delivery. The testing rig travels; the paperwork satisfies inspectors; and the systems that pass were built like it.
Should I test before replacing my HVAC equipment?
The sequence argument at its sharpest: replacement-grade money deserves to know what network it is buying into, since new equipment breathing through twenty-five percent leakage delivers seventy-five percent of its rating from day one, the disappointing-upgrade pattern the corridor knows well, and the pre-replacement test either clears the ducts, confidence for the equipment spend, or convicts them, the sealing or replacement scope pricing into the project while everything is open and coordinated, one disruption, one commissioning, the pair proven together. Equipment quotes that never mention the duct question are selling half a system; the test is how the other half enters the math; and the combined projects outperform their sequential cousins reliably.
Can the test find where the leaks actually are?
The number and the map arrive together: while the system holds test pressure, the reconnaissance walks it, theatrical smoke at accessible runs showing escape plumes, detection reading the plenum corners, boot penetrations, and return-side breaches, the census’s usual suspects confirmed or surprised, and the biggest individual routes flagged for the sealing scope, though the honest physics note stands, distributed leakage, dozens of small joints each contributing, is the common Texas finding, the map showing patterns more than pinpoints, which is exactly what mastic-everything sealing strategy answers. Wall-and-chase escapes beyond reach get the deductive read, supply-return isolation narrowing territory. The fix crew arrives knowing where to work; the after-test proves they did.
Related work: Air Duct Sealing · Air Duct Repair · Ductwork Design · see real jobs in the gallery
Get the Number First
An hour of physics, the leakage quantified in dollars, and every duct decision turned into arithmetic. Prefer to write it out? Send the form and we call you back.
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