A thicker filter (4-5 inches) has more surface area and therefore allows more room for air to pass through. Thick filters, due to their increased surface area, also have other benefits like: Higher dust-holding ability (meaning it can catch a lot without blocking airflow)
Thicker filters do a better job of keeping unfiltered air out, so you breathe healthier air. A four- to five-inch filter usually works best when you want superior filtration. But there are situations when a thin air filter is preferred.
In general, this is how often changing furnace filters needs to be done: For 1- to 2-inch filters, replace them every 1 to 3 months. For 3- to 4-inch filters, replace them every 6 to 9 months. For 5- to 6-inch filters, replace them every 9 to 12 months.
Stiffer builds for steadfast seal: 1-inch filters have less material to control, which means the frames are thinner. Thin frames have flimsy seals which let through unfiltered air, defeating the purpose of your filter. 5-inch frames are thicker and fit into the furnace more seamlessly.
The FPR ratings and their capabilities are as follows: FPR 4-5 (Green = Good): These filters are able to capture large particles such as dust, dust mites, lint, pollen and dander. FPR 6-7 (Red = Better): These filters are able to capture large particles and small particles such as bacteria and mold spores.
Do Higher MERV Filters Restrict Airflow? The higher a MERV filter, the more it filters the air with better efficiency. This means that a higher MERV will restrict airflow.
MERV‑8 filters are among the most popular choices because they strike a balance between performance and adaptability, fitting most systems without modifications. However, it's worth noting that filters with higher MERV ratings can restrict airflow.
What Is the Most Common Size of Air Filter for a House? The most common size air filter for a house is usually 20 x 20 x 1, but this can vary depending on the specific HVAC system installed.
Going down in thickness by an inch shouldn't be a big deal - for example, you should be able to use a 4-inch filter instead of a 5-inch filter. If you are considering a thicker air filter in order to improve air quality it may be better to focus on the MERV rating.
This extra depth gives the filter more room for airflow. That means that as the filter collects dirt and other debris from your air, it won't restrict the airflow in your furnace as much. This prevents damage to the furnace and gives the filter itself a longer lifespan.
Pleated filters are more efficient and will last longer than fibreglass filters, as polyester is much denser than fibreglass. The MERV rating of a disposable pleated furnace filter will range from 7 to 9.
Similar to the previous MERV filters, it is often recommended to replace MERV 8 filters every 90 days. As a side note, make sure to replace you air filter with the right air filter size.
Pleated filters with MERV ratings from 5 to 8 are classified as medium filters and are the most common in residential HVAC systems.
UNDERSTANDING FILTER SIZES
Therefore, for example, a 16x25x4 filter is 16 inches long, 25 inches wide, and 4 inches thick. It's important to note that filters with different dimensions are not interchangeable due to variations in frame size and media area.
FPR Breakdown:
1-4: Basic filtration, good for dust and lint. 5-7: Medium filtration, effective for pollen, pet dander, and mold spores. 8-10: High filtration, best for smoke, bacteria, and fine particles.
For 1- to 2- inch filters, replace them every 1 to 3 months. For 3- to 4- inch filters, replace them every 6 to 9 months. For 5- to 6- inch filters, replace them every 9 to 12 months.
MERV 11 is generally not too high for most home HVAC systems and provides effective filtration, capturing smaller particles like pet dander, pollen, and mold spores. This level is beneficial for households with allergy sufferers or pets, as it improves indoor air quality.
Usually they round up or down to the nearest inch, so it is less likely that these two filters will fit the same furnace because of the rounding. However, if your filter is close to 20x25x4. 5, and the actual dimensions of the 20x25x5 filter are closer to 20x25x4. 5, than they might fit.
Standard air filters have pre-defined nominal sizes for compatibility with most HVAC systems. Custom-made filters fit non-standard dimensions. The Nominal filter size for a custom filter may still round to convenient measurements, but its actual size matches the dimensions of the HVAC system or filter slot.
Damage to the HVAC System
Reduced Efficiency of the System: An improperly sized air filter can create an imbalance in the airflow, which means the system may not operate at its designed efficiency. When the HVAC unit is forced to work harder, it consumes more energy, leading to increased utility bills.
Filters with a MERV rating of 8-13 are usually higher-end filters for home use or high-quality commercial filters. These filters are typically the right choice for use in homes and many businesses.
High-MERV filters increase the static pressure of your system, and if the ductwork is already marginal, this can cause the airflow to drop to a level where the temperature exceeds the furnace's limit.
Expensive air filters are made from higher-quality materials, like fiberglass, that can last for up to 12 months. This not only saves you money, but it's also more convenient since you won't have to remember to replace your air filters as often.
The abbreviation stands for Minimum Effective Reporting Value. In other words, it's a measurement showing how small the holes are in the filter. The higher the MERV number, the smaller the holes, and the less that can pass through. Ultimately, this is what makes MERV 14 filters not a good choice for home use.