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Building Science

Why Don’t More HVAC Contractors Own Duct Leakage Testers?

With new energy code and green building program requirements on the horizon, we may be reaching a tipping point

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Every HVAC contractor has refrigerant pressure gauges in their truck. Why don't they also have a duct leakage tester?
Image Credit: Energy Vanguard
Every HVAC contractor has refrigerant pressure gauges in their truck. Why don't they also have a duct leakage tester?
Image Credit: Energy Vanguard
Anyone installing ducts needs to know their ducts don't leak. A duct leakage tester, though, is not a piece of equipment that most HVAC contractors own.
Image Credit: Energy Vanguard

HVAC contractors own a lot of equipment. Of course, they have pressure gauges to test refrigerant charge in air conditioners and heat pumps, and many more pieces of technical equipment. One piece that few contractors own, however, is a duct leakage tester.

With more and more state energy codes requiring duct leakage tests, doesn’t it seem obvious that HVAC contractors need to be like plumbers and test their own work before passing it off?

Ducts must be tested at the end of the job

Here’s another compelling reason for contractors to own duct testers: The Energy Star new homes program now requires the duct leakage test to be done at the final inspection, not rough-in. With Revision 06, footnote 17 in theHVAC System Quality Installation Rater Checklist says:

“Duct leakage shall be determined and documented by a Rater using a RESNET-approved testing protocol only after all components of the system have been installed including the air handler, the ductwork, the duct boots, and the register grilles atop the finished surface (e.g., drywall, carpeting, flooring).”

And just in case that isn’t clear enough, they wrote this in the Revision 06 Highlights:

To clarify, duct leakage testing must occur when the duct system is in its final state, which is to say after all components of the system have been installed including the air handler, the ductwork, the duct boots, and the register grilles atop the finished surface (e.g., drywall, carpeting, flooring). A leakage test at “rough-in” does not meet this intent, though may be helpful for identifying leaks that need sealing. [Emphasis added.]

I think this is a great change in the program because I’ve always had a problem with using a rough-in duct leakage test as the final result, which many HERS raters have done. Testing at rough-in is a great idea because you can catch problems before they become much more difficult and expensive to fix. Once the drywall goes up, access becomes a big issue. But as Energy Star now realizes, a rough-in test is not good enough to use in a home energy rating.

If you own your own testing equipment, you’ll be ready for inspection

Back to the original question now: why don’t more HVAC contractors own duct leakage testers? If they’re installing ducts, they really should ensure that the ducts have been installed and sealed properly. If a third party is going to come in when the house is complete and test for duct leakage, it only makes sense for the contractor to test at rough-in so they know they’ll pass at final.

I realize that there’s a lot of pressure on HVAC contractors working in new construction to keep their prices rock-bottom. Now, with building codes raising the standards, they’re being pulled in the other direction, too. It’s almost like homebuilders and code officials are doing an experiment to determine the tensile strength of HVAC contractors.

Can you spare $1,124?

I’m not an HVAC contractor, but if I were, I’d definitely own a duct leakage tester. They’re not really that expensive, as the prices have come down significantly in recent months. TruTech Tools is selling them for a little over a thousand dollars. Just 3 years ago, I bought one for nearly two grand.

Some people call me a purist because of my stands on issues like this. I guess I am, in a way. I also believe in following Steve Martin’s advice: “Be so good they can’t ignore you.”

In this changing environment for HVAC and homebuilding, you’ve got to be good.

Allison Bailes of Decatur, Georgia, is a RESNET-accredited energy consultant, trainer, and the author of the Energy Vanguard blog.


  1. wjrobinson | | #1

    And install ductless systems.
    And install ductless systems. Best price, and best efficiency. Happy customers and happy contractors and no added inspections.

  2. user-946029 | | #2

    I chose...
    ... to go with the Unico system. No joints; just a continuous duct with continuous insulation.

  3. watercop | | #3

    What range of SEER, EER, and
    What range of SEER, EER, and HSPF do Unico systems provide?

    My concern is that it will be difficult to avoid drafts with high velocity supply air.

    I'm all over minisplits whenever I get the chance:

    1) No ductwork to run
    2) SEERs in the 20s
    3) No ductwork to run
    4) Whisper quiet
    5) No ductwork to run
    6) components a fraction of the weight of conventional splits
    7) No ductwork to run
    8) Small diameter copper lines ridiculously easy to run and bend
    9) No ductwork to run
    10) True variable capacity, turndowns to 25% nominal capacity
    11) No ductwork to run
    12) redundancy
    13) No ductwork to run
    14) Defrost cycles without resistance heat (Magic, according to the local Mitsubishi trainer, since he lacked a better explanation)
    15) No ductwork to run
    16) Outdoor unit powers indoor unit - only one electric circuit

    Oh yeah, there's also no ductwork to run!

    I just wish some were made somewhere in North America.

    I own a DuctBlaster, but most of my new construction projects are sprayfoamed, so all ductwork and air handler is within the thermal and pressure envelope - its hard to get too excited about small duct leaks in that situation.

    What's all y'alls' take on the register / drywall interface? Sealing the boot to the back of the drywall is easy and sensible, but if the ceiling is at all textured there are gaps and leakage between the register and drywall; duct mask won't cover it, but the leak shouldn't count since it is into the conditioned room. I suppose I might have to invest in a set of register pans, but last I checked those were pretty spendy - as much as a ductblaster kit.

  4. user-626934 | | #4

    High velocity systems
    High velocity = high duct friction = high fan power to move the air through the ducts.

    I just searched the AHRI database for heat pumps that use a Unico-manufactured air handler. Here's the range of performance ratings I found:

    HSPF: 6.8 - 7.2
    SEER: 11.0 - 12.15
    EER: 8.45 - 10.05

    Underwhelming performance, to say the least.

    Also, it's not true that high velocity systems have no joints. They have plenty of joints....roughly the same number of connections as any other ducted system that uses full-length flex-duct for the branch runs. These systems can be leaky and they can be tight. They still need to be sealed up properly, just like any other ducted system.

  5. watercop | | #5


  6. stuccofirst | | #6

    register taping
    you have to tape all around the register in order to get an accurate reading of leakage. blue tape works well. peel slowly and hope for the best.

  7. watercop | | #7

    I had a callback to an audit
    I had a callback to an audit customer because the duct mask peeled paint off register grill.

    I definitely don't want to take on complaints about masking materials damaging drywall popcorn or otherwise textured ceilings

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