Thicker air filters are generally better than their thinner counterparts. They offer more longevity, improved airflow, and optimal filtering capabilities. If it's compatible with your boiler, consider investing in a 4-inch filter. It works more efficiently than a 1-inch filter.
When it comes to air filters, thicker is usually better. Thicker air filters tend to last longer because they have more square footage to capture and retain air particles. A 1-inch air filter may need to be changed every month, while a 4-inch air filter can last up to six months. Thicker filters can also trap more particles than a standard filter. Most air filters for heating, air conditioning and heating are 1 inch thick.
However, some need thicker filters, 4 to 6 inches. These can withstand more build-up, meaning you'll have to change them less often. But sometimes, these filters can limit airflow and cause system and air quality problems. My return grill has a typical 1 inch (14 x 24 x) filter and recently my service technician told me that there is a special grill filter that is 4 inches thick (it has an offset so it can fit in the return housing, not just the grill). They also told me that thicker filters will allow the system to work more efficiently, as they restrict airflow less.
In that sense, my understanding is that with the same MERV classification (that is, MERV 1), a 4-inch filter will be better than a 1-inch filter in terms of trapping more particles and having a less restrictive airflow. For example, you'll need to replace a 1-inch air filter every month, while a 4-inch air filter can last six months without needing to be replaced. However, if you can't determine how often you should change the filter, there are several warning signs to pay attention to; for example, if the air filter is full of dust or has stopped working properly, it's time to change it. With that said, the 1-inch filter can be too shallow, causing a loose fit that allows unfiltered air to enter the ducts. The width of an air filter is usually the longest side, and while the height is usually the shortest side, the longer size comes second. 4- to 5-inch air filters are usually better at providing a tight fit that prevents dirty air from passing through.
And while multimedia filters produce more airflow (less pressure drop) and clog less easily, you have to be careful with the MERV classification. Plus, they come in more than 30 different sizes, so it can be difficult to find the right air filter size. Reducing the thickness by one inch shouldn't be a big problem; for example, you should be able to use a 4-inch filter instead of a 5-inch one. But before you can answer the question: “What size air filter do I need?” it is essential to have the right dimensions. Understanding how air filter sizes work is crucial, especially if you want the right size for your home or office.
Some air conditioning specialists have also found that thicker filters are better at providing a perfect fit that prevents unfiltered air from passing through. On the other hand, you can sure use a 1-inch-thick filter in compartments that can accommodate a deeper filter. In general, 1- and 2-inch air filters are installed in standard HVAC systems, while 3- to 6-inch filters are installed in larger HVAC systems. The thickness of the air filter ranges from 1 to 5 inches deep; some options are more common than others, and your boiler may determine what thickness it can use.