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A/C Duct Tests

A/C Duct


An A/C duct test is another energy test for a home, where a small duct blaster fan is installed to the main return of the a/c system, along with covers placed on all supply and returns. Then a negative or positive pressure of 25 pascals is placed on the duct work, and calculated out. Once the calculation is done, the energy auditor can determine how loose or tight the duct work is.

The best time to perform a test is before drywall is installed, however the test can be performed after completion of home as well.

Some building departments require this test before issuing a Certificate of Occupancy. If the duct work is in conditioned attic space a duct test is not required.

In some cases, air losses of 20-30% can occur before air enters through supply grills, in turn, increasing energy bills and discomfort in the home. Pressure buildup in unconditioned space can also promote mold growth, and create more air leakage in the home. Also, air conditioners running constantly can be a sign that you may need a duct leakage test performed. 

Information provided by the U.S. Energy Information Administration in 2015, tells us that the average American household uses roughly 50 percent of its energy for heating and/or cooling. Duct leakage helps to make up for 20 % of annual energy costs. This does not even account for air losses from the drywall envelope which can add an additional 25-40% to heating and cooling costs.

Furthermore, a leaky system can shorten the life of your air handler and condensing unit, costing a homeowner thousands in replacement and repair costs in shorter spans. 

If you're thinking about getting a duct test done, please don't hesitate to give us a call!


How it Works

By pressurizing a homes duct work to 25 pascals, the machine is able to determine the amount of air leakage in the A/C system. Usual problems of poor workmanship can fortunately be quickly remedied typically with tape and mastic. 

Frequently Asked Questions
  • Do I need a blower door test?
    If you have just about finished a residential home, or you have done major renovations, then YES, you will need a test(s) done, just before your get your final building inspection in order to receive your Certificate of Occupancy. These tests are also a great additional inspection for real estate, prior to purchasing a home or commercial building.
  • Where can I find what tests need to be done?
    Typically on the energy calculations sheet in fine print near the energy auditors seal.
  • At what point of new construction is a blower door test performed?
    A blower door test can be performed at any time, but for Florida Code compliance, it-is conducted just before the Certificate of Occupancy (CO) is issued, after all piping, wiring and other penetrations of the building thermal envelope have been sealed. Please make sure to have all drywall openings closed up before calling us out for an inspection. If Icynene (Spray Foam) Insulation has been used a blower door test can be performed earlier on in the build. If regular blown-in or batt insulation has been used it is recommended that all electrical covers, drywall holes, and all penetrations otherwise, be finished. If baseboard is noticeably above the floor throughout the house, it is also recommended that they be caulked to the floor to insure a passing score.
  • Can we be inside while the test is performed?
    Workers and homeowners may be in the house during the test, we will just need all the doors and windows closed. Results are given on the spot after performing the test, which takes about 30 minutes. The house will only need to be closed up for a very short duration after the blower door setup is installed in an exterior door.
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