I recently bought 4 – 20"x25"x5" MARV13 filters. When they arrived, I was surprised how light they were compared to the previous brand filter with the same specs I had been using.

My previous brand filters had 21 pleats and Filterbuy only have 16. The previous brand filter material also was 2 to 3 times as thick. Loosing 5 pleats causes a reduction of surface area of approximately 1000 square inches of filter material. That is about a 25% reduction in surface area.

The old filter would last greater than 3 months, the Filterbuy filter lasted 1 month. I noticed the heater was tripping off on high temperature, I suspected the high limit switch but after some investigation I concluded that the filter was the issue. I replace the 1 month old filter with a new filters and have not had the issue in 3 days. I also measured the temperature at the high limit switch with the 1 month old filter and a new filter. The old filter quickly rose to 160+ degrees and the new filter only rose to 120deg. This indicated that the old filter was severely restricted. Look at the photo and tell me that looks like a clogged filter, the only explanation is that it has less surface area and the filter material is sub par.

The photo is of the 1 month old filter with a light behind it. There is no way this filter should be restricting air flow to the extent that it is causing the Temp Rise to exceed the heaters upper Limit.

Unfortunately it was Christmas eve when I discovered the issue and I did not have an option to buy one from a local store. That meant I had to use another $35.00 filter that will only last 1 month.

I contacted Filetrbuy customer service to tell them about the issue and was told I could return the other 2 unused filters but I would have to pay the return shipping. I pointed out the issue with the filter prematurely clogging up and they had nothing to say except "Our filters are tested prior to shipping and we do adhere to all ASHRAE 52.2 standards and we are UL listed."

They will not stand behind their products.

I will never buy from them again.