When it comes to selecting the right size for your air filter, there are a few things to take into account. The first is the “real dimensions”, which are the actual length, width, and thickness of the filter. This size is usually indicated on the filter itself, just below the nominal size. If it isn't, you can measure the filter to get the correct measurements.
It's also important to make sure that the filter has a foam seal on the outside for a perfect fit. Another factor to consider is the MERV rating. MERV stands for Minimum Efficiency Reporting Value and it tells you what size air particles an air filter can trap. The higher the rating, the smaller the particles it can trap. For instance, a 1-inch air filter may need to be changed every month, while a 4-inch air filter can last up to six months. Most online air filter retailers have a custom air filter page where you can find a variety of sizes.
If you're not sure what size you need, you can always measure your current air filter. A 1-inch filter with less surface area will clog up quickly and need to be replaced more often than a coarser filter. In general, filters with 1- and 2-inch air filters are installed in standard HVAC systems, while 3- to 6-inch filters are installed in larger HVAC systems. If your oven's air filter compartment is only 3mm thick, then a 1-inch oven filter is the better choice compared to a 4-inch filter; however, a 3-inch thick air filter is still the better option. Plus, there are more than 30 different sizes available so it can be difficult to find the right one. Combining a thin air filter with a high MERV rate can also restrict airflow and cause excessive wear.
The easiest way to determine the size you need is to remove the current air filter from your air conditioning system. When selecting an air filter size, it's important to consider both real dimensions and MERV rating. Make sure that your chosen size has enough surface area for efficient filtration and that it has a foam seal for a perfect fit. Additionally, if you're not sure what size you need, measure your current air filter or remove it from your HVAC system.