In some cases, using an air filter that is too restrictive for the system can lead to low airflow problems. The MERV 13 is the highest, safe MERV rating for residential furnaces; higher values are typically used in commercial units. This decreased airflow can also have an unwanted effect on the cooling side. The air conditioner has a hot coil on the outside, the condenser, and a cold coil in the air handler on the inside.
This cold coil has an optimal operating temperature based on a certain amount of hot air flowing through it and the refrigerant that passes through the copper tube in that coil. With a higher MERV filter that reduces airflow through this crucial part of the air conditioning system, the cold coil can eventually freeze and turn into an ice ball, completely blocking airflow. This can cause costly problems in the outer capacitor coil. The American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) recommends MERV 13, but it may not be the most efficient option for some residential HVAC systems.
While MERV 8 is known to be effective at filtering airborne contaminants such as pollen, dust mites, sawdust, mold spores and lint, higher MERV rates will further clean the air. MERV 13 filters, for example, also remove bacteria, tobacco smoke, car fumes, insecticide dust, pet dander and more. When selecting an air filter for your furnace or air conditioner, it is important to consider both efficiency and airflow. A filter with a higher MERV rating will provide better filtration but may reduce airflow if it is too restrictive for your system.
If you are unsure which filter to choose for your HVAC system, it is best to consult a professional to ensure you get the best performance from your system. It is important to remember that while a MERV 13 filter may provide superior filtration capabilities, it may not be suitable for all residential HVAC systems due to its potential to reduce airflow.
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