• Pentair Lid Kit Sys3 Flt 21" | 24851-9000
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Pentair

Pentair System 3 Filter Lid Kit, 21" | 24851-9000

Pentair System 3 Filter Lid Kit, 21" | 24851-9000

$877.66
$877.66
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⚠ Discontinued Product
The Pentair 24851-9000 System 3 Filter Lid Kit, 21" has been discontinued and is no longer being manufactured. This listing is maintained for part identification, compatibility reference, and replacement research. Availability should not be assumed unless inventory is specifically shown.
Pentair System 3 Filter Lid Kit, 21" | 24851-9000

The Pentair 24851-9000 System 3 Filter Lid Kit is an OEM replacement filter lid designed for compatible 21-inch Pentair System 3 pool and spa filters. The filter lid forms the upper section of the filter tank and is critical to maintaining a properly sealed, secure pressure vessel during normal filtration.

If an existing System 3 filter lid is cracked, structurally damaged, distorted, or otherwise unable to seal correctly, replacing the damaged lid can help restore the integrity of the filter assembly. Always verify the filter model, tank size, and manufacturer part number before ordering a replacement component.

Product at a Glance
  • Brand: Pentair
  • Manufacturer Part Number: 24851-9000
  • Product Type: Filter Lid Kit
  • Filter Series: Pentair System 3
  • Nominal Size: 21"
  • Application: Swimming Pool & Spa Filtration
  • Part Position: Upper Filter Tank / Lid
  • Product Status: Discontinued

What Is the Pentair 24851-9000 Used For?

Pentair part 24851-9000 is used as a replacement upper lid on compatible Pentair System 3 21-inch filter assemblies. The lid closes the upper portion of the filter tank and helps contain system pressure while pool water moves through the filtration system.

A damaged filter lid should not be treated as a cosmetic issue. Cracks, deformation, damaged sealing surfaces, or other structural problems can interfere with proper sealing and may compromise safe filter operation.

Why the System 3 Filter Lid Matters

Maintains Tank Integrity
The lid forms part of the filter's pressure-containing tank assembly and must remain structurally sound during operation.
Helps Maintain a Proper Seal
A correctly fitted lid works with the filter sealing components to help prevent water leakage at the tank closure.
OEM Pentair Replacement
Part number 24851-9000 identifies the original Pentair replacement lid kit for its intended System 3 application.
Important Filter Safety Notice
Pool filters operate under pressure. Never attempt to remove, loosen, repair, or replace the filter lid while the system is pressurized. Shut the pump off, isolate the system as required, and completely relieve internal filter pressure before servicing. A cracked or structurally damaged pressure-vessel component should not be patched or temporarily repaired for continued operation.
Verify Your Existing Filter Before Ordering
Pentair System 3 filters were produced in multiple sizes and configurations. Do not select a replacement lid based only on appearance. Confirm the filter model, tank diameter or size designation, and Pentair part number 24851-9000 whenever possible.
Specifications
Manufacturer Pentair
Part Number 24851-9000
Product System 3 Filter Lid Kit
Size 21"
Equipment Type Pool / Spa Filter
Filter Family Pentair System 3
Component Location Upper Filter Tank / Lid
Status Discontinued
Compatibility & Fitment

Pentair 24851-9000 is intended for compatible 21-inch Pentair System 3 filter assemblies.

Because System 3 equipment was manufactured in different sizes and configurations, the correct replacement lid should be identified using the original filter model and parts information rather than appearance alone.

  • Confirm your equipment is a Pentair System 3 filter.
  • Confirm the applicable 21" size designation.
  • Compare the original part number with 24851-9000.
  • Inspect associated sealing and closure components during lid replacement.
Discontinued Product & Replacement Information

Pentair 24851-9000 has been discontinued. The original 21" System 3 Filter Lid Kit is no longer being manufactured.

Because the lid is part of a pressurized filter vessel, replacement selection should be based on confirmed manufacturer compatibility. An unrelated filter lid or visually similar component should not be substituted unless specifically approved for the filter assembly.

If a direct replacement is no longer available, the appropriate repair path may require evaluation of the complete filter assembly rather than attempting to modify or repair a structurally damaged lid.

Installation & Service Guidance

Replacement of a filter lid requires the filtration system to be completely shut down and depressurized before disassembly.

  • Turn the circulation pump off before servicing.
  • Completely relieve filter pressure before opening the tank.
  • Inspect the filter sealing surfaces and related hardware for damage.
  • Inspect the applicable tank seal or O-ring and replace it if damaged or deteriorated.
  • Make sure the lid is correctly seated before securing the filter assembly.
  • Follow the filter manufacturer's service and startup procedures before returning the system to operation.
Frequently Asked Questions
What is Pentair part 24851-9000? Pentair 24851-9000 is a 21" replacement filter lid kit used with compatible Pentair System 3 pool and spa filters.
Is Pentair 24851-9000 discontinued? Yes. Pentair 24851-9000 has been discontinued and is no longer being manufactured.
What filter does Pentair 24851-9000 fit? It is intended for compatible 21-inch Pentair System 3 filter assemblies. The exact filter model and existing part identification should be verified before replacement.
Can I repair a cracked Pentair System 3 filter lid? A cracked filter lid is a damaged pressure-vessel component and should not be treated as a cosmetic repair. A structurally compromised lid should be replaced with a properly rated compatible component or the filter assembly should be evaluated for replacement.
How do I know if my System 3 lid needs replacement? Cracks, deformation, damaged sealing surfaces, persistent leakage, or other structural damage can indicate that the lid requires replacement. Shut the system down and relieve pressure before inspecting the filter.
Can I use a different-size System 3 filter lid? No replacement should be selected solely because it looks similar. Filter lids are pressure-containing components and must match the intended filter configuration and size.

Common Part Searches

Pentair 24851-9000, Pentair 248519000, Pentair System 3 filter lid, System 3 21 inch filter lid, Pentair 21" filter lid kit, Pentair System 3 replacement lid, Pentair pool filter lid, Pentair filter tank lid, System 3 filter replacement parts.

About Pentair Pool Equipment
Pentair manufactures pool and spa equipment including filtration systems, pumps, heaters, automation, sanitization equipment, lighting, and replacement components. When servicing legacy Pentair equipment, matching the original manufacturer part number and equipment model is especially important because similar-looking components may be designed for different filter sizes or configurations.
Pentair 24851-9000 is Discontinued
Use Pentair part number 24851-9000, the System 3 filter family, and the 21-inch size designation when identifying this legacy filter lid or researching the correct replacement path.
Pentair System 3 Filter Lid Kit, 21" | 24851-9000
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