I’ve been working in the Heating & Air Conditioning business for many years, in their bookkeeping department. And so I pretty much thought I knew all there was about Heating & Air Conditioning, but I was wrong. And I had never heard of MERV when I had a customer call and ask me what MERV would be best for her new oil furnace! She was confused by the color ratings on the air filters and by the MERV, too. I told her that I was unsure, and so I called a Heating & Air Conditioning technician over into the office to have him deliver his advice to her. Apparently the higher the MERV rating is, the more efficient the air filter is. While listening to him talk to her on the phone, I learned that MERV is an acronym for Minimum Efficiency Reporting Value. The company she was ordering her air filters from, made it easy for you to know if you had a good MERV rating or a low one. Their Bronze air filters had a MERV of 6, while their Silver air filters had a MERV rating of 8, and their Gold air filters had a MERV rating of 11. I guess the rating was developed by a group of Heating & Air Conditioning engineers. It helps to rate the effectiveness of the air filter. And I guess not all air filters are alike. Apparently, there are lots of different sizes and there are those that are HEPA filters. HEPA filters have the highest ratings, meaning that they can help keep out germs and microorganisms that can contaminate the air quality. And so, from now on, whenever I go to buy air filters for the oil furnace or for the a/c, the first thing I will be sure to do is check the MERV. Because why have an air filter, if it isn’t doing a great job?