Heating, ventilation, and air conditioning (HVAC) units are essential for keeping homes and businesses comfortable. They are responsible for regulating the temperature, humidity, and air quality of the space. HVAC units work by circulating air through the building, using a combination of heating, cooling, and air-filtration systems. Heating systems typically use a furnace, boiler, or heat pump to generate warm air, while cooling systems rely on an air conditioner, evaporative cooler, or heat pump to keep the air cool. The air is then filtered through an air filter to remove dust, pollen, and other airborne particles. HVAC units are also responsible for maintaining proper ventilation in the space, ensuring that the air is not stale or stagnant. By controlling the temperature, humidity, and air quality, HVAC units ensure that the space is comfortable and safe for occupants.