Air filter @ FurnaceAC or only @ Intake Air Vent? -

Master Flow 16 in x 25 in Return Air Box with Filter Rail RAB16X25 return air box with filter slot Return air filter box and grille 2 qty MERV 13 18x20x2 inch filters (5 Slot Diffusers & Returns · Spiral Duct Diffusers · T-Bar Plastic Supply return of kong slot return air box for side air return The built-in 16” x 25” x 1″ filter rack simplifies filter maintenance Actual product may vary slightly from what is

return of kong megaways slot Is is common that there is a filter both at the return air intake AND at the furnace? slot for a filter if you choose to use intake