It was air that had sealant particles in it.
For a long time my energy bills were just too high. I immediately was ready to blame my Heating and Air Conditioning equipment. It was old, damaged and dirty. No wonder my bills were so high. I had a Heating and Air Conditioning supplier over to the condo to do some cleaning, tightening and repairing. There was a small loose area and another one that was covered in rust. After the repairs I was ready to experience lower energy bills. Nope, everything stayed the same. I started googling what was the problem. I was closing the curtains in the Summer to avoid the hot light coming in. In the Wintertide I put towels under the doors to stop air from leaking out. I even caulked around all the windows. So what was the problem? I called my Heating and Air Conditioning professional back and told him about my energy concerns. She immediately knew what was up. The woman inserted a camera into my HVAC duct to take a peak. She found a undoubtedly small tear along a seam of my HVAC duct. That small tear meant all the treated air my Heating and Air Conditioning created was leaking outdoors. How the woman performed HVAC duct sealing was easily cool. She took what looked like a squirt gun and shot it into my air ducts. It was air that had sealant particles in it. The sealant can service major holes to minor tears like mine. After messing around with that, she evaluated the camera again and fixed the tear. I noticed a difference in my energy bills immediately afterwards. It is amazing how much of a change it was.