In general, it is recommended to have an air filter on each return grille (as long as you choose the one of the correct size and thickness). Filters will improve the air quality in your home and protect your HVAC equipment from dust, pollen, pet dander, and hair. You must place a filter in the return vent near the return bank connection on the air handling unit. The return vent filter will keep the air clean and remove particles that lead to poor air quality.
Install a filter in the return vent to clean the air inside your home. Your air conditioning system must have a suitable filter on the return side. By attaching a high-quality, well-fitting filter to the return vent, you will remove particles from the air before they can enter the air conditioning system. A good filter will keep the air handling unit, coils, and ducts clean.
If the filter doesn't fit properly, it can be as bad as not having a filter. If return ventilation does not appeal to you, you can purchase decorative grilles that can improve the appearance without obstructing the flow of air through the return air vent. Most people find return air vent unattractive and will ask if they hide return air vent with furniture or a picture. Maintaining the air cleaner and return air vent will go a long way in helping the heat pump last for many years.
Another way to avoid the use of return ventilation filters is to place a filter in the return air duct just before it enters the air conditioner. If your air conditioner has a fresh air inlet, you'll need to put a filter in the duct or external ventilation, as well as on the return grilles. Some people want to place filters in the return grilles to prevent dust from accumulating inside the return air duct. The principle is the same as the original AC filter, but it forgets the original location of the filter and places it in the return duct.
The size of the return air vent is in direct correlation with the amount of return air needed by the heat pump. While your HVAC system will likely have a filter built into the system itself, many homeowners are starting to install return air filters in their home's ventilation grilles as well. The return air outlet is located near the thermostat, so that the air entering the heat pump system closely matches the temperature shown on the thermostat. However, if your air conditioner is working properly, you're more than ready for a return vent filter upgrade.
Some people want to filter more dust and are thinking about putting filters in the AC return grilles. A good central air conditioning system has return ventilation in each room to precisely control the temperature of each room and maintain the same air pressure in each room.