MERV 13 air filters can cause cold coils to freeze, leading to expensive problems in the condenser coil. This is due to the reduced air flow that occurs when using a higher MERV filter. The cold coil has a preferred operating temperature based on the amount of hot air that flows through it and the refrigerant that runs through the copper tubing. Without proper air flow, the cold coil can eventually freeze and restrict air flow completely.
Most modern HVAC systems have no problem working with higher MERV filters, so millions of homeowners rely on them. The main risk of high-efficiency air filters is that they remain unchanged for long periods of time. If you're dedicated to changing filters, it's unlikely that you'll experience any filter-related problems with your HVAC system. A MERV score of 13 to 16 is considered hospital-level air quality, so it's unlikely that your home needs more than that.
According to the United States Environmental Protection Agency, filters in the range 7 to 13 often have little difference from higher MERV indices, but they will allow the system to operate much more efficiently. Air filters with a thick media filter can trap small particles, such as pet dander and mold, without impeding air flow like a thin, pleated air filter would. Low-efficiency filters are usually inside MERV 1-4 and high-efficiency filters are MERV 13 and later. It's important to note that as the MERV rating increases, the filter becomes more restrictive and more pressure and energy will be needed to expel air.
Also consider running the system fan longer or continuously, since HVAC systems filter the air only when the fan is running. Air filters with MERV 13 or higher are recommended for those who prioritize air quality and may have to endure asthma, severe allergies and other similar circumstances. A clogged air filter allows dust to build up inside the system, allowing more contaminants to enter the air in the house and restricting air flow to the boiler or air conditioner, causing the equipment to overheat and fail. When these filters become dirty and need to be replaced, air can continue to flow through them and not become clogged as easily.
Any air filter rated higher than 13 will restrict air flow to the point of damaging the air conditioning system, which would entail an additional expense to repair it. In conclusion, while a MERV 13 filter won't necessarily hurt your AC unit, it's important to be aware of how it can affect your system's performance and efficiency. It's also important to remember that as the MERV rating increases, so does the risk of damaging your AC unit if you don't change your filter regularly. Be sure to check your filter regularly and replace it when necessary in order to keep your AC unit running smoothly.
