Yeah, I know 1" filters stink. I will be getting a serious media filter once I can scrape the funds together- maybe an F100. I promise not to install it myself; I want my guy to come back and seal it with mastic and warranty it. In the meantime, though, I'm trying to find a 1" filter that provides *some* level of particle filtration without too much pressure drop.

I've got a 16x25x1" filter rack. The system peaks at 1050-1150 cfm on high heat (depending on if it's set in Comfort or Efficiency). Total static is right at the upper limit (1", on this unit) with something like a 3M Filtrete installed. I ran a 3M Ultra Allergen for a month in this system, and although it didn't look dirty, my tech checked it before he replaced it with his filter on my PM visit, and we had almost 0.40" drop across the filter itself. No wonder 3M doesn't publish the pressure drop for the Filtrete.

I found this MERV 8 filter that seems to have static pressure about as low as anything I can find in an afternoon of Internet sleuthing... and I give Purolator major credit for actually publishing specs for pressure drop across their filters, unlike so much of the competing 1" filter market. I was interested to see how much pressure drops could vary from one brand to the next. I had assumed that a MERV 5 filter would probably be less restrictive than a MERV 8, but that wasn't really the case. Evidently there must really be some difference in the media and pleat design, too.

http://www.purolatorairfilters.com/p...m/DMK80Lit.pdf

For those who don't want to load the PDF, they claim 0.14" drop at 850 cfm and 0.34" at 1400 cfm. That sounds decent to me, but I am just a lowly homeowner who has spent waaaay too much time hanging out on this board. I can get a 12-pack delivered for a little over $50, which kicks 3M's butt.

Anybody else know of a pleated 1" filter that's less restrictive than this? I don't need hyper-allergen-trapping stuff like MERV 11, but I don't want to go back to the 50 cent spun filters, either. Is there a good middle ground out there? Is this it, or should I look at some other 1" filter?

Thank you all, again, and as usual.