Product Overview
The Pentair 170020 FNS Plus Tank Lid Assembly is a genuine OEM replacement upper tank section for the Pentair FNS Plus 36 sq ft D.E. filter. This lid assembly forms the top half of the filter tank and provides the upper sealing surface needed for proper clamp band and tank O-ring fitment.

This replacement part is commonly used when the original tank lid is cracked, leaking, damaged, or no longer sealing correctly. It is designed to restore the structural integrity of the filter housing without replacing the complete filter system.

Ideal For
Replacing the upper tank lid assembly on a Pentair FNS Plus 36 sq ft D.E. filter model FNSP36.

Key Features

• Genuine Pentair OEM replacement part
• Designed for Pentair FNS Plus 36 sq ft D.E. filters
• Replaces the upper tank / lid assembly
• Helps restore proper filter tank sealing
• Provides the upper sealing surface for the tank O-ring and clamp band
• Durable molded tank construction
• Used for cracked, leaking, or damaged filter lids
• Compatible with FNS Plus 36 sq ft D.E. filter systems
• Helps avoid full filter replacement when only the lid is damaged

Benefits
The Pentair 170020 tank lid assembly helps restore safe and proper operation of the FNS Plus filter housing. A damaged lid can cause leaks, pressure loss, clamp sealing issues, or unsafe filter operation. Replacing the upper tank section with the correct OEM Pentair part helps maintain factory fitment and reliable performance.

This is a practical repair option when the lower tank, clamp band, grid assembly, and other internal parts are still in usable condition.

Compatibility
Designed for the Pentair FNS Plus 36 sq ft D.E. filter, commonly identified as model FNSP36.

Always confirm your filter model number, tank size, clamp style, air relief assembly, and parts diagram before ordering. Older FNS Plus filters may require inspection of the clamp band, O-ring, and related hardware before replacing the tank lid.

Specifications

Important Installation Note
Before servicing or replacing the tank lid, fully turn off the pool system, open the air relief valve, and make sure all filter pressure has been released. D.E. filters operate under pressure and can be dangerous if opened while pressurized.

During replacement, inspect the tank O-ring, clamp band, air relief assembly, pressure gauge, internal manifold, grids, and lower tank sealing surface. Replace worn or damaged seals and hardware as needed.

Customer-Facing Q&A

Q: What is Pentair part 170020 used for?
A: It replaces the upper tank lid assembly on the Pentair FNS Plus 36 sq ft D.E. filter.

Q: Which filter does this fit?
A: This part is designed for the Pentair FNS Plus 36 sq ft D.E. filter, model FNSP36.

Q: Is this the complete filter?
A: No. This is the tank lid / upper tank assembly only. It does not include the full filter, lower tank, complete grid set, clamp band, or plumbing connections unless otherwise stated.

Q: Will this fix a cracked filter lid?
A: Yes, if the damage is limited to the upper tank lid and the rest of the filter is still in good condition.

Q: Should I replace the tank O-ring at the same time?
A: It is recommended to inspect the tank O-ring and replace it if it is worn, flattened, stretched, cracked, or leaking.

Q: Does this include the air relief valve or pressure gauge?
A: This listing is for the tank lid assembly. Confirm current packaging before publishing if your inventory includes or excludes the air relief assembly or pressure gauge.

Q: Is professional installation recommended?
A: Yes. Because this is part of a pressurized D.E. filter system, professional installation is recommended.