Rusted Ductwork in a Tight & Dirt Covered Crawl Space Gets Swapped Out With Our HVAC Duct Service in Johnson City, TN

Received a call from an existing customer in Johnson City, TN requesting our HVAC Duct Service in order to replace a rusted out duct in her crawl space. The duct boot had rotted out at the supply register and the metal duct itself had rotted out as well. When we arrived we looked at the job under the house which was a tight fit in some places requiring a combination of hands and knees as well as belly crawling about 60 feet to the work location. The duct insulation was failing which caused the duct to rot out, the incorrect tape was used on the joints, some joints weren't even sealed, none of it was screwed together, the duct ran off the end of the supply trunk which you should never do, and there was an existing 6" hole in the side of the supply trunk that had been taped with duck tape and the tape had failed. The unit had been heating and cooling the crawl space and that air was not being recovered during operation.

We gave the customer several options to choose from for the repair. We offered to go back with metal ductwork with exterior R8 foil faced insulation and we offered a R8 flexible duct replacement as a cheaper option. We also explained that the end of the supply trunk needed to be patched up and sealed because a duct should never leave the end of a trunk line. We explained that we should use the existing hole on the side of the supply trunk where the duck tape had failed to run the new duct. We also explained that we would need to install a new duct boot and seal it with a mold resistant, low odor, metal safe, high temperature silicone sealant at the duct boot and under the floor as well to prevent crawl space air from entering her home. The customer decided on the more budget friendly option of flexible duct.

We gathered the materials for the job and returned to the home another day to perform the job. We removed the existing duct boot, the metal duct and insulation, no start collar was used at the supply trunk, and when someone had installed the duct off the end of the supply trunk they had removed the insulation off the end of the supply trunk which caused rust to form on it in a bad way. We custom fabricated a metal patch for the end of the supply trunk, screwed it into place, and sealed it with duct mastic infused foil tape. While performing this work I took at shock through my head and out my hands into the crawl space dirt floor. We found that the foundation repair that was done on the home many years ago was hot with electricity. The metal jack posts where we were working along with the metal girder had 115 volts flowing through it to ground. We immediately let the homeowner know about the issue and we spoke to an electrical company on the phone to let them know of our findings and even texted them pictures of the problem area along with pictures showing how much voltage was flowing through the metal to ground.

After dealing with the electrical issue with the customer's electrical company we went back under the home and we removed the failed duck tape from the 6" opening on the side of the supply trunk. We installed a 6" 90 degree adjustable elbow metal take off, screwed it to the supply trunk, and sealed it up. We attached a 6" metal adjustable elbow to the new duct boot and confirmed our angles we needed. We screwed the metal together and sealed up every joint in the connection that could potentially leak any air. Then, we attached the 6" R8 flexible duct to the metal adjustable elbow. We used a 36" Panduit strap and secured the flexible duct to the elbow. We put screws through the Panduit strap and into the metal connection and sealed it up with duct mastic infused foil tape. We pulled the R8 insulation up and over the duct boot and sealed up that connection as well to prevent sweating in cooling mode.

We pushed the duct boot up into the sub-floor and crawled out from under the house and made the connection on the main floor. We sealed up the duct boot from up top with the silicone sealant we had discussed with the customer. We went back under the home and sealed around that penetration with the same silicone as well to serve as a redundant back up to the seal up top. We placed a Panduit strap around the insulation of the flexible duct and secured it to act as a redundant back up to the duct mastic infused foil tape.

We stretched out the flexible duct to ensure proper airflow through the duct line and hung the duct along the crawl space joists and used 2 screws on each side of every strap location. We ran the duct across the work area strapping it up as we went. We made the connection to the 6" metal 90 adjustable elbow take off that we previously secured and sealed up. We followed the same procedure as the other side making sure to Panduit strap the liner, screw through the Panduit strap into the metal, and to seal the liner and strap with duct mastic infused foil tape. We pulled the insulation over that connection to protect it from sweating in the cooling mode and sealed the insulation to the trunk line. Then, we secured a Panduit strap around the duct insulation to act a redundant back up to the tape.

We used 2 layers of Reflectix foil insulation with an air gap between the layers at the end of the supply trunk line. We sealed the insulation to the trunk line. Then, we used 2 layers of 3" R8 fiberglass insulation stacked on top of each other over top of the 2 layers of Reflectix for added insulation at the end of the trunk line. We coved the 6" of fiberglass insulation with a protective foil facing and sealed it to the end of the supply trunk line to ensure it won't sweat in the future and rot out the metal patch spot.

We cleaned up our work area of tools and debris, removed the old materials from under the home, and tested the system in the fan on position. We checked for any performance issues or air leaks. We fired the unit in cooling mode and checked the performance of the duct. We looked for any signs of air leaks or condensation and cycled the unit back to the customer's desired cooling set point once we were satisfied with our findings.

If you are in need of a thorough HVAC Duct Service, please feel free to reach out to Magnolia Services based out of Johnson City, TN. We don't take shortcuts, we do the job right, and our work is levels above what others will perform. Stay safe and best wishes.

Location: Johnson City, TN