Sealing a New Duct System

“Why do I need to seal my new duct system?”

Anytime in this state (NC) you install a new duct system you have to do what’s called a duct test, or duct blaster as we call it, you have to measure how much leakage is in that duct system. There is a point, and it depends on what inspections want to see, if it’s 5–10% of leakage in the new duct system. Let’s go with a round number, let’s say it’s 10% leakage, you are leaking 10% of the energy you are paying for out of the duct system. If you seal it, you will get down to 0% that is obviously more efficient than losing 10%. That is why you want to seal the new duct system.

In this area we see a lot of duct board, a fiberglass duct system, that duct system is bad for your lungs and for your health. We go back and install metal duct that way you are not breathing in the fiberglass any longer. The downside to installing that metal duct is you have joints and no matter how much you try, you seal the joints with mastic, tape, insulation, you seal that up on top of the mastic and the tape and you still are at 10% leakage. There is no way a human being can actually seal all the places the air flows.

Now with a duct sealing machine, it works on pressure. It is an aerosol, there is not a human putting mastic and painting on the joints. It is a machine, it is all controlled by the computer program and it is working on pressure and it is filling the holes with the glue as it finds the leaks. That is the most efficient way to do it. If you are okay with 10% leakage, wasting 10% of your energy bill, that is cool just keep doing it. Most people are not. I would recommend after that duct test to make a decision. If you have a 2 ton system and you are leaking 3–4% if you are fine with that then that is fine. If you have a 3,4,5 ton system and you are leaking 10% that adds up to be quite a lot of money. That is why you need to seal a new duct system.

Now duct board, fiberglass duct, there is less leakage in that than a metal duct but there is always a give and take. You breathe in the fiberglass, which is not good, some people and some companies still use fiberglass. Once fiberglass becomes airborne and gets in your lungs there is no way it is coming back out. We don’t install fiberglass in your system, we go with metal because it is a lot cleaner, a better install, and once you seal it it is a no brainer really. You are not breathing in the fiberglass, you are stopping the dust and the dirt from coming in to the duct system from the outside because now it is sealed.

Your friend in comfort and energy savings,

Derek Cole

Derek Cole is the General Manager of One Hour Heating & Air Conditioning®, an independently owned and operated franchise based in Laurinburg, North Carolina since 1953. He has more than 15 years of experience in the HVAC industry and has created two You Tube broadcasts, The Comfort Experts and #AskDerekCole, filled with tips and tricks on saving energy and being comfortable. He was named the Top 40 under 40 in the HVAC industry by the News magazine and featured in Entrepreneur Magazine Franchise Player Spotlight. Derek has also been seen on CBS, FOX, NBC, ABC, Huffington Post, and Bloomberg Business sharing about One Hour Heating & Air Conditioning® and home comfort tips.