I find it kind of funny how people throw the term HVAC around, and expect everyone to know what it was. I’m not trying to be snarky about it, but I know it is the furnace and air conditioning unit. So, what does the entire thing stand for? When I had my furnace serviced, I asked the HVAC technician. He made it sound like a simple answer, but I still had questions. He said H was for heating, V was for ventilation, and AC was for air conditioning. I understood the heating and air conditioning, but where did the ventilation come in. He said that most businesses and homes have ductwork installed in the ceilings and walls. The ductwork is used to carry the heat or air conditioning to the rooms. It is a ventilation system that uses the fans from the furnace and the AC unit to blow the air throughout the house. In large buildings, they have a complete ventilation system that can be connected to several heating and air conditioning units. You can also consider the bathroom fans and the fans in the stove hood; ventilation systems. The air purification system we had in our home was also part of the ventilation system. If there wasn’t enough airflow going through the ventilation system, the heating and air conditioning would not work properly. I was well-informed now, but I felt stupid that I hadn’t thought of it on my own. Now that I understand what HVAC stands for, I know I should have figured it out without talking to the HVAC technician.