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Mission: HVAC 2015 – Challenge Five: The Quest for Full System Closure

by | Jun 30, 2015 | Mission HVAC

Full system closure means that an HVAC system is installed with absolutely no air leaks. It’s important as an unsealed system may allow moisture, dirt, dust, bacteria or insects in, negatively affecting indoor air quality. Not to mention the increased risks for energy loss, higher utility bills and even system failure. These failures will cause customers to complain and demand that you come back to fix the job, which can damage your reputation and your bottom line.

What did our Mission: HVAC students learn? Read below to find out!

Daniel: The QuestDaniel - May Quest Image_0

The Heating, Ventilation, and Air Conditioning (HVAC) trade represents one of the most important fields of work serving residential and commercial properties because it helps maintain a balanced and comfortable indoor environment for all. Studies and research in the HVAC field are performed worldwide, around the clock, to improve comfort and system efficiency.

One of the most important aspects of a high-performing system, besides having an operative condenser and evaporator unit, is an airtight ductwork system with no leaks. Air leaks are the number one cause of increased energy costs, diminished system performance and eventual system failure. In one of the textbooks I use in class, I learned that the three basic goals in duct designing are:

  • Knowing the system’s CFM (Cubic Feet per Minute).
  • Understanding the maximum system static available (maximum static pressure available to move the needed quantity of air).
  • Noting the Duct Friction Rate (Resistance the duct material has to the air flow).

To achieve a complete duct system closure, the HVAC technician must have tape. HVAC tape can be used in air handlers, filter housings, duct joints and registers. Tape technology is a major contributor to performing our duties as HVAC technicians well and achieving better results and success.

Josue: Making Sure Air Loss is Minimal

For this mission, we looked into ductwork installation and repair, as well as the effect of having properly or improperly installed ductwork. I asked a few friends about this issue and read up on the topic. I’ll be covering the most essential details I learned from my research.

First of all, it’s nearly impossible to completely seal off a duct system, but systems should only have minimal air loss. When installing air duct, you must know what type of mastic and tape to use for the different types of duct materials. When installing metal duct, you must use a tape that’s UL 723 certified. When installing rigid duct, the tape needs to be UL 181A certified for it to work. When installing flex duct, the tape must be 181B certified.

Always check with state and local codes to make sure your duct installation will pass inspection. For example, in the state of Georgia – where I live – you need to conduct a duct blaster test after new installations. A duct blaster test will ensure that you have airtightness in the duct system.

When you have properly installed a duct system, it should operate at or near 100 percent efficiency. This means it will have a longer lifetime and save money over the years. If the system is improperly insulated or sealed, it will easily cool or heat the air duct system, which may counteract the effort made by the system.

Matt: Keeping Ducts Secure is a Multi-Step Process

At Jordan Air, where I am currently employed, I started out as a seal and wrapper. Today I work as a new installer. We make sure that all new ductwork and seal and wraps are airtight with no more than 5- to 10-percent leakage.

The first step is to tape all seams with cold-weather tape. Then we paddle the tape to ensure tightness. Next, we apply mastic tape to all metal joints and wrap the ducts with air gap. After that, we apply small bubble foil duct wrap insulation, equal to R-6, around the entire length of the pipe and tape all seams. Finally, we apply big bubble foil duct wrap insulation, equal to R-8, and tape all seams once more.

One of the main ways to check for air leaks is by using a duct blaster. We start by taping all vents and all returns, except for one, and then connect the system to it. The duct blaster is used to blow air through the ductwork while the system is off. The duct blaster will inform you of how much loss you have. If it is greater than 10 percent, the system needs to be repaired.

For repairing older systems, we start by cutting back the insulation, then we place duct and mastic tape across all seams and finally reapply insulation.

Full system closure is important because without it, power bills will increase and the life of the system will shorten. A system that is properly installed will last between 10 and 15 years.

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