If your system only fits a 1 or 2 inch filter, a high MERV rating could be detrimental. A 1-inch filter with less surface space will clog up fairly quickly and will need to be replaced much sooner than a coarser filter. The higher the MERV rating, the better the filter will stop particles. This means that a 1-inch filter with a high MERV rating could perform just as well as a 2-inch filter with the same rating. My sister can get quite cheap 3M oven filters.
However, the size my oven has installed right now is 20x25x2 inches, and the only ones you can get are 20x25x1 inches. Get a cheap inch and an expensive 1 inch and place the face one second after the cheap one in the airflow. The cheap one will act as a pre-filter that filters out big things like cats or hair. Sure, but remember that the two filters together aren't good until a 2-inch filter. Two good filters can prevent airflow enough to cause problems, but the cheap+good one should be fine as long as you don't release them until they're dirty.
Honestly, just put on a filter, with a little adhesive tape to keep it in place. Don't do this, both filters have twice the surface area of filters 1.The filter material itself has the same thickness. You can put a single filter 1, but it will clog twice as fast. Honestly, it's probably not the same material.
Both filters have twice the surface area of filters 1.Somehow, the only correct answer is at the bottom. Frugal is not spending pennies chasing pennies. I work with HVAC, you can do it. You won't notice any difference. Filters only work if air has to pass through them.
The filter has air resistance and a gap does not, so if you leave a gap of 1, a disproportionate amount of air will flow through the hole, which will worsen the situation. We have taken this particular question to break it down with an elaborate answer. For example, we have put a comparison of 4 inch vs 1 inch oven filters. But in a broad sense, this is a comparison of “thin filter versus coarse-grained filter”.
Check the filter every 1-2 months during heavy use and change it when necessary to avoid the types of efficiency and mechanical problems described in the section on 1-inch oven filters. 1-inch pleated air filters have higher MERV ratings for one simple reason: they have more surface area to trap particles. If a certain amount of dirty air passes through both, the number of “unclogged” pores will be greater in a coarser filter than in a thinner one. The smaller filter area will behave like a filter that is already partially dirty, but you can use it temporarily. If it's choosing a smaller filter or nothing at all, at least do something like taping or taping a piece of cardboard filler to the filter to get the right size.
But why is there such a big difference in their lives? This is because thicker air filters have more square feet. And that brings us to a face to face comparison between the 1 and 4 inch oven filter before selecting the next filter replacement. You would have to replace filter 1 twice as much as filter 2 and risk damaging the air handler (fan motor) by increasing the resistance you have to press against. Therefore, if you choose a filter 1 with a high MERV rating, you will have to change it every month or two when the oven, heat pump, or air conditioner is used a lot. That's a technical way of saying “how many and how small particles do you filter out of the air you breathe”.