Are High MERV Filters Bad for Your Furnace?

When it comes to air quality, the highest MERV ratings are the most effective. However, they can also cause damage to your air conditioning system. This is because a higher MERV rating means greater resistance, which in turn leads to less airflow. When researching HVAC systems, airflow is a major factor.

Generally speaking, filters with higher MERV values are able to capture higher percentages of particles, as well as smaller particles. MERV-13 is usually the ideal rating. The short answer is yes, but it's not really a problem unless in extreme cases. Most modern HVAC systems have no issue 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 diligent about changing your filters, it's unlikely that you'll experience any filter-related problems with your HVAC system.

Some technicians anticipate that people will forget to change their filters, and regular use of low-efficiency filters could help minimize damage to a neglected HVAC. Increasing a filter to a higher MERV can increase the delta P through the filter. This means that the fan will have to work harder to get air through the filter due to the restriction, which can damage the unit and make it more expensive to repair over time. It takes time for the filter to charge sufficiently for a beneficial effect, so that everything that goes through the filter ends up in your system or in your home. Masks should be changed frequently, at least daily, so I have several and wash the mask, then soak the filter in alcohol and then place it on a clean surface to dry. Since a buildup of particles can block air flow and reduce the efficiency of the air conditioner and oven, most people assume that thinner and thicker filters will have the same effect on the oven, since the air will pass through more filtration points as it enters your air controller. When these filters become dirty and need to be replaced, air can continue to flow through them and not become clogged as easily. Air filters with a MERV of one to four are effective at removing large particles, such as carpet fibers, airborne paint droplets, and sanding dust.

However, they cannot help with contaminants such as hairspray, mold spores, or even flour that could have escaped from the mixer. Simply replacing a 1-inch filter with a 4-inch filter may not be sufficient, especially if the filter cabinet is mounted immediately before the fan (properly sized for the return opening). Ironically, the effectiveness of low-efficiency air filters increases as the filter is filled with dirt and dust. Raising just three MERV rating levels can be a smart decision that makes the air cleaner - or a harmful option for your entire HVAC system when you consider the air flow capabilities of the MERV 8 versus the MERV 11. Filter technology has advanced significantly over recent years and MERV ratings are designed to help us determine which air filter options are most effective and efficient for heating and cooling systems and more. From sizes to types, qualities and more - here's everything you need to know about air filters.

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