The general rule of thumb is that one air filter is necessary for each air handler. Most homes, especially those with multiple HVAC systems, have more than one filter installed. These are usually placed near the oven or air conditioning system and return grilles. It's important to understand that the number of filters needed depends on the configuration of your HVAC system.
Each system has an air filter, which can be located in the air handling unit and in the returns. To make sure you've found all of your air filters, you should check every possible location. Air filters are essential for maintaining air circulation and ensuring good indoor air quality for the whole family. It's just as important as changing the oil in your car, according to home expert Mike Holmes of the DIY Network series “Holmes on Holmes”.
Your oven is like the second group of lungs in your home. If you don't change the filter often, you will tend to have a respiratory problem inside the system. The most common type of filter is not popular with homeowners due to its low filter quality. However, one type that can be particularly difficult to find at the local store is the whole house air filter.
Sometimes, an HVAC air filter location can be found behind a return air grille to allow easy access when it comes time to change the filter. It's also important to note that stacking two filters will cause your system to work too hard, leading to long-term damage to your components. Households with a lot of occupants and pets will likely need to change their air filters more frequently. When it comes time to change your air filter, you should be aware of all the different sizes, types, grades and more that are available.
Electrostatic filters clean the air by creating static electricity that acts like magnets that adhere dust and contaminants to the sheet. The sheet should remain white or any shade close to it; if it turns gray or black, it's time for a new filter. It's important to have expert knowledge of a wide range of home air filtration topics, including HVAC filters, filtration efficiency, and indoor air quality. Even though you might think that two filters side by side would clean the air better, that's not exactly the case. The reason there is a pair of filters is because it is necessary to filter both the air that travels to the air handler and the air that passes through the return grilles.