I was hearing the air hiss every time the gas furnace turned on! There was less heat coming through the air vents, and I knew our gas furnace was running for longer periods of time, i told the Heating and Air Conditioning business receptionist that I wanted someone to inspect our gas furnace and do a great inspection of the HVAC duct. I was hoping I needed repairs to the gas furnace, although I was sure I was going to need to replace the HVAC duct, and when the Heating and Air Conditioning professional was done with his inspection, he told me I had holes in that HVAC duct that were so big, a small rat could get through. I cringed, thinking I had rats in the house. I asked if our HVAC duct was absolutely that ratty. He said there were no rats yet, but that was how important some holes wereâ€¦ Most of our heat was escaping into the basement, and somewhere else where the holes were. He told me I had to replace the entire HVAC duct system, which was going to be quite luxurious. I didn’t even want to know about the cost. He explained how they now made a flex pipe HVAC duct. It was stretchy and took up less room that the metal HVAC duct. The cost was almost half of what it would be to make the metal HVAC duct and it didn’t rust through. I liked the thought of flex pipe HVAC duct, and asked when he could have it installed. He measured up the amount of flex pipe I would need and gave me a estimate for the HVAC duct and the upgrade, and although it was still wildly luxurious, it was a lot cheaper than traditional metal HVAC duct.