12 Filter Replacement Pads for Envirosept 1625 Package of 12 EnviroSept furnace filter pads for Envirosept Furnace Panel HVAC air purifier model 1625 Panel NOT included . Exact sizes are 14 by 22 inches. Note The Actual Size of the Furnace Panel is 15.5 inches by 24.5 inches although the unit is called a 1625. Use 2 replacement pads per filter change for best results.Replace filter pads monthly or more often if your home or business requires it. Note Measure the panel insert including the black plastic piece to get accurate dimensions of your Envirosept insert. Replacement furnace filter pads cover only the inside mesh part of the furnace air cleaner panel. Replacement furnace filters are made from a custom polywool blend of proprietary fibers without latex or adhesives. We suggest a label on your furnace to remind you of the size. To Replace Furnace Filters Unplug the unit. Remove furnace filter panel from the slot. Open the two retaining clips. Remove both filters. If desired,move the less dirty filter to where the dirtier filter was. Add second filter. Push the clips closed, slide panel into slot and plug in. This item ships from a separate warehouse and may require extra time for delivery.