In most cases, a MERV 11 air filter is not too tall for residential use. Generally speaking, anything below a MERV 13 air filter should provide very efficient air purification in a home without affecting airflow. Although MERV 13 is suggested by the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE), it may not be the most efficient option for some residential HVAC systems. In fact, MERV 11 may even be too restrictive.
It's best to comply with oven manufacturer's recommendations or consult an HVAC professional to determine exactly which MERV rating is best for your specific system. The higher the filter rating, the smaller the particles it will capture and the higher the percentage of particles captured. Low-efficiency filters are generally within MERV 1-4 and high-efficiency filters are MERV 13 and later. The MERV scale is not linear; the difference between a MERV 6 and a MERV 8 is almost double in the percentage of particles captured.
Keep in mind that as the MERV rating increases, the filter becomes more restrictive and more pressure and energy will be needed to propel the air. In general, a filter with a higher MERV rating will reduce airflow. However, there are many other factors at play, such as the size of the filter and the type of fan motor in your HVAC system. Opinions vary widely on the subject, but all professionals agree that a good HVAC air filter is necessary for your home because they have seen all the problems that a wrong type of air filter can create in a home's HVAC system.
Burned motors and controls can result from overly restrictive filters. Coils, motors, and blowers can also be easily clogged by weak filters, creating greater fan usage, resulting in higher energy costs. If your oven's MERV rating is too high, it can force your oven to work too hard and leave it vulnerable to damage. In addition, you may not get the air velocity needed to reach all parts of your home, leaving temperature inconsistencies.
In operating rooms and other spaces where absolute cleanliness is required, filters with a MERV rating of 17 to 20 are used. A MERV rating of 13 to 16 is considered hospital-level air quality, so it's unlikely that your home will need more than that. For most Canadian homes, oven filters with MERV ratings in this range are sufficient to filter out a good majority of airborne impurities. If your home's HVAC system is unable to handle MERV 13, opt for a filter with the next highest possible rating.
At the heart of an optimally functioning HVAC system is an oven filter with the right MERV rating for you. By the way, surgeries have a variety of Merv filters, and HVAC systems use Merv filters; in both cases, they don't use fiberglass. A MERV 8 carbon filter will provide more than enough filtering of dust and allergens and will filter dozens of toxic gases that will pass directly through a MERV 13 filter. Many people don't consider how a filter with a high MERV rating will affect other parts of the HVAC system.
It is essential to remember that the MERV rating of an air filter denotes its lowest possible capacity, that is, the minimum percentage of impurities it could effectively filter. This may not seem like a significant difference compared to the MERV 8 filter, but a MERV 11 is also better able to capture between 65% and 79% of the smallest particles. A MERV filter 13 is likely to help if the goal is to prevent droplets from passing through. Strict building codes and an increase in foot traffic generally mean that commercial properties must opt for a filter with a higher MERV rating.
Airborne pollutants in most homes will be captured on a filter with a MERV rating between 8 and 13. Finally, I say that there is no price for peace of mind and that if they feel that a high MERV filter would provide, they should do so with the caveat that they should replace dirty filters often enough - which can be a week or two depending on the MERV rating, effective filter area and amount of particulate matter entering your home.