Shortly after buying our home, my husband and I started having problems with the heating and cooling system. The equipment ran continually yet failed to meet demand. Despite extremely high energy bills, the house was either a bit chilly in winter or overheated in the summer. Adjusting the thermostat simply put greater strain on the system without achieving optimum comfort level. We also noticed a great deal of airborne dust and a musty smell. We hired several different contractors to inspect and service the air conditioner and furnace. Over and over again, we were told that there was nothing wrong with the equipment. We were advised to change the air filters more often. I finally contacted an HVAC contractor who specialized in duct system services. The technician inspected the ductwork and found all sorts of issues. The duct system was extremely old and poorly designed. Sharp bends in the system caused a buildup of dust and debris, which then blocked airflow. With less heated/cooled air entering the home, the system was forced to run longer and work harder to achieve thermostat settings. The accumulation of contaminants also impacted our indoor air quality, introducing dust and harmful spores into the home. There was also leaks at the seams and holes in the ductwork, which allowed our conditioned air to escape and pulled in outside air. Unfortunately, the HVAC contractor did not believe sealing and cleaning would resolve the issues. He recommended replacing the entirety of the duct system. It was a huge, involved and expensive project, but necessary and worthwhile.