The answer to 'how often to replace air filter' is that most experts recommend replacing your HVAC air filter every 1-3 months, or at least 3-4 times per year. This helps maintain the efficiency of your heating and cooling system and ensures good indoor air quality in your home.
The exact replacement frequency can vary based on factors like the type of filter, the size of your home, whether you have pets, and how often the system runs. Filters in homes with more occupants, pets, or heavy usage may need to be changed more frequently. It's a good idea to check your filter monthly and replace it when it looks dirty or clogged.