Duct testing is an important part of ensuring the safety and efficiency of HVAC systems. It is a process that involves using specialized equipment to measure the pressure of air in a duct system. This article will provide an overview of the two standards for duct testing, as well as the equipment and procedures used to perform the tests.
What are the Standards for Duct Testing?
The two standards for duct testing are the SMACNA Air Conditioning Duct Construction Standards, Fourth Edition and ASHRAE SPC215P.The SMACNA standard requires that tests be conducted at a pressure of 25 Pascals (Pa) or 0.1 inch. The ASHRAE SPC215P standard specifies which methods should be used to determine leaks.
What Equipment is Used for Duct Testing?
A technician uses a duct tester to perform duct pressure tests. This equipment includes a fan, pressure gauge, and supplies to seal all HVAC vents and create a closed system.The test equipment is connected to a return vent or controller of air. If the test equipment is within the area normally conditioned by the system, a door or window must be opened to ensure that the outside area of the ducts is subject to outside air pressure.
What are the Different Types of Duct Tests?
There are two types of duct tests: duct pressure or leak tests (DP) and external leak pressurization (LTO) tests. The DP test measures the amount of air leaks in all ducts connected to the air conditioning system, including those located both outside and inside.The LTO test measures the amount of air leakage from outside sources into the conditioned space.
When Should Duct Tests be Performed?
In the case of a duct system with three or more returns, the total leak measured by Rater is allowed to be equal to or greater than ≤ 6 CFM25 per 100 square meters. Some builders prefer to wait until the last test of the pipelines, as other traders are likely to move them in the meantime, and the pipelines will follow being accessible. When all ducts are located in conditioned spaces, the total duct leak test is only necessary if certain conditions exist.What Other Procedures Should be Followed During Duct Testing?The evaluator must also visually check, when entering, that the ducts are completely insulated (with an R-8 for the supply ducts and an R-6 for the return ducts and other ducts) along their entire length, including all connections, and that the insulation is not compressed by tight belts, structural elements or excessive bending. Information provided to test ductwork leaks in new homes also applies to existing homes. If leaks in the ducts are tested at time of entry, a HERS evaluator must confirm and document that total leak in ducts is greater than ≤ 4 CFM 25 per 100 square feet of conditioned floor area or ≤ 40 CFM25 using a test protocol approved by Resnet, and must verify through visual inspection that covers are sealed to finish surfaces at end.
Why is it Necessary to Check Ducts for Leaks?
One may wonder why it is necessary to check ducts for leaks if the ducts and the air handler are located in a conditioned space.Leaky ducts can be major source of energy loss and comfort problems, and they can contribute to humidity problems especially when passing through an unconditioned space such as ventilated attic or mezzanine. Duct testing is an important part of ensuring that HVAC systems are safe and efficient. It involves using specialized equipment to measure air pressure in a closed system, as well as following certain procedures such as visual inspections and total leak tests. By following these standards and procedures, technicians can ensure that their HVAC systems are functioning properly.