comments:
Kinda surprising that they went with a pleated filter for the coarse (G4) exit air filter? Seems like a depth-loading ('forest of fibers') filter would be lower resistance, hold more dust, and be washable?? But I guess business is gonna business... for the coarse G4 filter, just cut and remove the pleated filter and replace it with a depth-loading dual density blue-and-white bulk roll HVAC material. It should attach with hot glue. Fluff up the material a bit, and make sure when assembling that the air goes in the white side and out the blue side. You can then pre-soap the fibers for even better particle removal efficiency (I use dilute seventh generation unscented) and simply rinse clean and re-spray with the soap solution when it gets dirty. I would build two filters actually, so you can have one prepped and ready to install while you clean and prep the other one. for the all-important air inlet F7 filter, ditch the tiny integrated filter entirely (make a "blank" filter with the pleated material cut out if necessary to make the machine happy), and connect an AC Infinity 6" duct filter box between the ERV and the outside air intake. This will let you use standard 12x20x1" Filtrete 2200 filters, which should avoid choking out the flow when cutting down a 2200 to only half a square foot. The box looks big in the picture but it's actually only 8.5" x 23.5" x 11.75" (including the 6" duct flanges), so it should fit "sideways" in less height than the ERV which is 21.4" x 47.2" x 12.4".
Best washable pre-filter is the blue-and-white depth-loading bulk media filter that comes in a big roll, like this: https://www.amazon.com/Filter-Media-White-MERV6-Polyester/dp/B017WOXA4Y To catch the most dust, you can dilute some dish soap (I use seventh generation unscented) and spray it on the clean filter before installing it. The soap helps grab extra dust, improving it from a MERV 6 to a MERV 7-8. And when you go to wash it, the soap is under the dirt so it rinses clean easily. Here's a video demo. You can use those cheap filters in a CR box configuration as an inexpensive filter holder, then simply tape/tie the cut-to-fit material over that. EDIT: the airflow direction is going "in" the white side and "out" the blue side.