Filters don't need to have a “hermetic seal”, but they should be easy to install and uninstall, and not be so small that they move freely within the unit. In short, yes, you can cut off an air filter if you know what you're doing, and if the filters aren't weakened too much from the cut. An oven filter should fit snugly inside the unit. If it is too loose, air will continue to enter even when the oven is running.
On the other hand, if it's too tight, you may not be able to remove the filter when it's time to change it. Installing several 1-in-a-slot air filters can cause costly damage to residential ovens, as they are not equipped to handle this level of airflow restriction. These filters offer excellent filter quality and are often found in hospitals or other areas that require the cleanest air. This is especially true if you have a HEPA filter installed in your HVAC unit, as these filters outperform dedicated air purifiers when it comes to removing particles from the air.
Replacing your air filter regularly is essential if you want your HVAC system to run efficiently. You can find the recommended filter size for your unit model in the table titled “Find your air conditioner and oven filter by make, model number and size”. Washable air filters are reusable versions of normal flat panel or pleated filters. These high-tech electric purifiers use static electricity to filter particles from the air, like a much more advanced version of an electrostatic filter.
To make sure that the next filter you purchase is the correct size for your system, measure the inside dimensions of the air cleaner inlet. An electrostatic air filter is a filter that has been charged with static electricity; this traps small particles such as mold and bacteria and keeps them in place, improving the efficiency of the filter. Filters ensure that the air entering and circulating through your home is as clean as possible, so it's important to inspect your heating system annually and replace parts that need replacing. Generally, you'll see filters with a MERV of less than 4 in residential ovens, window-mounted air conditioning units, or as a pre-filter in commercial units that need multiple filters.
Air filters work best with a tight fit, but if the filter is larger than it should be, don't try to bend or trim it yourself to adjust its size; this won't seal properly and air will leak through and around curves. In the long run, it's much cheaper to replace the filter regularly than having to replace the entire air conditioner. Additionally, having a clean filter will keep your home air fresh and hypoallergenic, making it an important step when replacing your oven filter. If the filter is not the correct size - either too small or too large - air will flow around instead of through it, meaning not all of the air will be filtered out. If you think it's OK to run your heating system without a filter until you get one that fits in your oven, think again; this is absolutely not OK.