When an oven filter is placed upside down, the fibers cannot do their job properly. This means that your oven has to work harder to generate the same airflow, resulting in increased energy costs. Particles are also allowed to accumulate unevenly, causing the oven to work even harder to extract air. The biggest damage that can result from a filter installed upside down is that it can damage your HVAC system and reduce its lifespan.
An AC filter installed upside down will greatly slow down airflow, your oven will have more difficulty operating. When efficiency decreases, the likelihood of a system failure, such as a refrigerant line leak or a failed compressor, increases. The biggest problem with installing an air filter upside down is that the oven has to work harder to do its job. One side of the filter is more porous than the other. A furnace or central air unit that has to draw air through the non-porous side of a filter loses efficiency and runs longer, requiring more energy because it slows down the flow of air through the heat exchanger, according to Bob Vila.
The result is an increase in your utility bill and additional wear and tear on your HVAC system. So what happens if the air filter is improperly installed? Air filters are built to be installed in a certain direction. Installing the air filter backwards can restrict airflow through the air cleaner, cause the filter structure to fail, and allow dust, dirt, and other debris to pass through the filter and accumulate on the evaporator coil. If the evaporator coil becomes dirty, the system will not operate at optimal efficiency and could clog the condensate discharge line and cause the system to fail. The most common problem you'll face with a rear-facing filter is simple inefficiency.
If the oven is forced to blow air through the non-porous end of a filter, more energy will be needed to do so. The blower will overwork and pay more money for your heating. The same goes doubly with an air conditioner that has several filters in place to keep outside contaminants out of the indoor air. It won't make any difference. The filter will continue to work exactly the same as if it had been positioned the right way.
The reason there is an arrow is because the filter on one side has a mesh that prevents filter material from entering the oven, but that is quite rare. I've seen a lot of filters upside down without any problem. I know, I know it's a silly mistake, it's my first home and I've only been here for a few years, apparently at some point I mixed up the direction of the arrow into my filter and I've been placing them incorrectly. If no air filter is present in the air return, these airborne contaminants end up accumulating in the evaporator coil. In addition to dust in the evaporator coil, when dust coats the fan, fan motor, and other internal components of your oven, it will also lower the efficiency of the system for heating and cooling. Especially with older gas ovens, there is even a potential fire hazard due to this overheating process.
Under the exhaust pressure of the blower fan, these filter structures will eventually fail over time, causing the cardboard filter frame to bend or even bend in the return box. Whether the oven filters are located in the plenum inside the oven cabinet or in the cold air return near the ceiling, they should always be installed with arrows pointing towards fan motor (the direction of air flow). When air starts to flow around the filter, it can make your system dirty by putting a layer of dust on your evaporator coil. Even with proper air filter maintenance, you should have your HVAC system cleaned and serviced at least once a year. This is because AC filters are designed in a way that allows for even distribution of dust within their material rather than just on their surface. However, there is a right way to install your home's air filter and installing it upside down can waste money and cause long-term damage to your system if you're not careful. Air filters have direction arrows which indicate which way they should be installed on return.
If you ask a service person to install air filters take a look at how they are placed and where arrows point. Air filters especially basic ones capture large particles in air but allow many smaller particles pass through them. Filter is designed remove large amount of unwanted debris but only when installed in certain direction. New homeowners or renters who don't understand HVAC system well may have problems with this simple step of properly orienting filter.