The answer to 'air duct sealing not heating' is that poor air duct sealing can be a common cause of ineffective heating in your home. Leaks and gaps in the ductwork allow heated air to escape before it reaches the rooms you want to heat, reducing the overall efficiency of your HVAC system.
Some common symptoms of air duct sealing issues include uneven heating, rooms that never seem to reach the desired temperature, and higher energy bills as your system works harder to compensate for the air loss. The good news is that duct sealing is often a relatively straightforward DIY project, but for more extensive problems, it's best to call in a professional HVAC technician.