The 28361WF is manufactured by Airguard for WaterFurnace and is considered by WaterFurnace to be the OEM replacement 1" MERV 11 air filter for their Geothermal Comfort Systems that use a 28 x 36 x 1 pre-filter.
The replacement filters used with WaterFurnace units that use a 28 x 36 x 1 pre-filter must use a filter that is a full 28" x 36". If you use a smaller filter sold by other manufacturers, your filter will not seal properly and you could get unfiltered air leaking around the edge of the filter, this is called bypass. The 28361WF MERV 11 air filter is approximately 28" x 36" x 1" and is the size recommended by WaterFurnace for a proper fit.
The 28361WF is made of 100% synthetic fibers that are needled together and then electro statically charged. The needled fibers create a dense mat that produces a MERV 11 rating and higher mechanical efficiency at a lower air resistance than other pleated filters. For more information on the construction of this replacement air filter please review the Airguard PowerGuard Air Filter Specifications.
The manufacturer suggested replacement interval is 4 to 6 months, depending upon conditions and lifestyle.
For instructions on how to change your furnace's air filter, please refer to your unit's Owner's Manual.This package ships with 4 filters.