What is a Duct Leakage Test?
A Duct Leakage Test is a form of quality control performed by a certified third-party technician to verify the airtightness of ductwork in new and existing homes. The equipment is comprised of a specialized fan that is attached to the furnace at the point of airflow. The fan is then connected to a manometer, which is an instrument used to measure the rate of airflow.
All registers throughout the home are carefully sealed using tape or other air-tight materials. The fan is then set to draw air (like a vacuum) through the tightly sealed system. Because all the registers in the home have been sealed, any measured airflow must come from leaks that are allowing air into the system. The measured airflow determines the leakiness of the ductwork being tested.
A Duct Leakage Test can take place either during construction after the ductwork is installed but before the sheetrock is hung or at the very end when the home is complete. Most cities and towns in Rhode Island, Massachusetts, and Connecticut require a document generated by a HERS rater or other certified technician verifying a passing grade for this test.
What is Acceptable Duct Leakage
In order to better understand what is acceptable please refer to the following from the energy.gov website.
“Your air ducts are one of the most important systems in your home, and if the ducts are poorly sealed or insulated they are likely contributing to higher energy bills.
Your home’s duct system is a branching network of tubes in the walls, floors, and ceilings; it carries the air from your home’s furnace and central air conditioner to each room. Ducts are made of sheet metal, fiberglass, or other materials.
Ducts that leak heated air into unheated spaces can add hundreds of dollars a year to your heating and cooling bills, but you can reduce that loss by sealing and insulating your ducts. Insulating ducts in unconditioned spaces is usually very cost-effective. Existing ducts may also be blocked or may require simple upgrades”.
As mentioned above, all new homes built in Rhode Island, Massachusetts, and Connecticut are required to pass a duct leakage test as part of the construction process. Passing results for a Duct Leakage Test are measured in cubic feet per minute or CFM. Presently in Rhode Island the acceptable rate of system loss is no more than eight percent. In Massachusetts and Connecticut it’s four. To help clarify, if building a 2000 sq. ft. home, the allowable air leakage could not exceed 80 cfm.
How Hard is it to Pass a Duct Leakage Test?
Most HVAC contractors working in new homes today are aware that the quality of their work will be tested. They should carefully seal all seams on the main trunk, all lateral takeoffs from the main trunk as well and all registers in floors, walls, and ceilings. Specialty products such as mastic and high-grade foil tape when properly applied will help to ensure a passing grade.
What Happens if You Fail a Duct Leakage Test?
Here are some options you can try should your home fail to make the grade during a duct leakage test.
- Remove floor registers and make sure that all connections are tightly sealed.
- Check the furnace cabinet for excessive leaks and seal as needed.
- Check the main trunk where exposed for areas that may not be properly sealed.
- Check lateral supply lines coming off the main trunk. The point where the laterals connect to the main trunk is crucial. Be extra diligent when checking here.
- Make certain to repair any duct insulation that gets damaged during the inspection process.
Before starting your next building project contact the Staff at Energy Geeks. From the design stage at the very beginning to the Certificate of Occupancy needed at the very end, we will advise and guide you, thus helping to assure that your next building project will be a success.