Pentair 170021 Tank Lid Assembly – for FNS Plus 48 sq ft D.E. Filter

This Pentair 170021 is a replacement tank lid assembly designed for use with the FNS Plus 48 sq ft vertical D.E. filter system. It restores the sealing interface and structural integrity of the filter tank assembly.

Key Features

• Direct replacement lid designed for the 48 sq ft filter tank size.
• Durable construction to maintain proper filtration pressure and seal performance.
• OEM part fit ensures compatibility and avoids having to replace the entire filter tank.

Technical Specifications

• Part Number: 170021
• Application: Lid for vertical D.E. filter tank, 48 sq ft size.
• Use Case: Replacement when the original lid is cracked, warped or fails to seal properly.

Installation & Compatibility Notes

Shut off the pool pump and relieve pressure in the filter tank. Remove the old lid assembly and inspect tank rim and seal surfaces for damage. Install the new 170021 lid, ensure the O-ring or gasket is properly seated, and clamp or bolt the lid according to manufacturer specification. After installation, restore flow and monitor for correct pressure behavior and absence of bypass or leaks.

Maintenance Tips

• Inspect the lid annually for signs of cracking, warping or damage around the rim.
• If the filter pressure drops off or the lid hangs open/moves under pressure, a replacement lid is often the solution.
• Stock this lid as part of your service inventory to quickly address common filter tank issues without replacing the entire unit.

Why Choose This Lid Assembly?

For pool service professionals and retail storefronts, stocking the Pentair 170021 lid assembly provides a cost-effective way to restore filter system integrity. It enables longer equipment life and avoids full tank replacement while delivering correct fit and performance.