Waterfurnace Geothermal 28x36x2 MERV 11 Airguard Air Filter (4PK) Discount

The 59P509-05 is manufactured by Airguard for WaterFurnace and is considered by WaterFurnace to be the OEM replacement MERV 11 air filter for all their Geothermal Comfort Systems that use a 28 x 36 x 2 pre-filter.  

The replacement filters used with WaterFurnace units that use a 28 x 36 x 2 pre-filter must use a filter that is a full 28 x 36 .  If you use a smaller filter, such as many of the 27 1 2 x 35 3 4 filters 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 59P509-05 MERV 11 air filter is approximately 28 x 36 x 1 3 4 and is the size recommended by WaterFurnace for a proper fit. 

Common WaterFurnace Geothermal Heat Pump Models that use the 59P509-05 28 x 36 x 2 MERV 11 pre-filter:

Envision Series:
Single Speed Vertical Units: NLV080, NLV095, NLV120

The 59P509-05 is made of 100% synthetic fibers that are needled together and then electrostatically 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 the 59P509-05 replacement air filter, please review the Airguard PowerGuard Air Filter Specifications.

WaterFurnace Premier Series units have an air filter rack that can be set for 1 or 2 when the units are installed. In most situations, you will not be able to change your units filter rack size without altering your ductwork, so please make sure your unit s filter rack is set for 2 filters. If your unit s filter rack is set for 1 filters, please get in touch with us for a quote on the exact filter you need.

All WaterFurnace units that use a 28 x 36 x 2 air filter actually use two 18 x 28 x 2 filters stacked. The 59P509-05 filter is made of two 18 x 28 x 2 air filters taped together. If your unit has an H channel between its air filters, remove or cut the tape to separate the two filters.

The manufacturer suggested replacement interval is 4 to 6 months, depending upon conditions and lifestyle.