Pentair FNS Plus Tank Lid Assembly 36 sf | 170020
Pentair
SKU: 170020
Pentair 170020 Tank Lid Assembly for FNS Plus 36 Sq Ft D.E. Filter (FNSP36)
The Pentair 170020 is an OEM replacement tank lid assembly for the Pentair/PacFab FNS Plus 36 sq ft vertical-grid D.E. filter (commonly referenced as FNSP36 / FNS Plus 36). This is the upper tank half (lid/top shell) that clamps to the tank bottom and seals with the tank clamp and tank O-ring.
Compatibility
- Fits: Pentair / PacFab FNS Plus 36 sq ft D.E. filter
- Common model reference: FNSP36 (36 sq ft vertical-grid D.E. filter)
- Part type: Tank lid / upper tank half assembly
Always verify your filter model and parts diagram before ordering. FNS Plus lids differ by filter size (24, 36, 48, 60 sq ft).
What This Part Does
- Forms the upper half of the filter tank housing
- Provides the clamping/sealing surface for the tank O-ring and clamp band
- Helps maintain a pressure-tight filter tank during normal operation
When to Replace the Tank Lid
- Cracks, hairline fractures, or visible leaks from the upper tank shell
- Warping or damage that prevents a proper seal with the tank O-ring
- Damage at the clamp contact area from age, overtightening, impact, or UV exposure
- Persistent leaks after replacing the tank O-ring and confirming clean sealing surfaces
Installation Notes
- Turn off the pump and relieve all filter pressure before opening the filter.
- Inspect and replace the tank O-ring if it is flattened, cracked, swollen, or nicked.
- Clean all sealing surfaces thoroughly before reassembly.
- Reinstall the clamp band evenly and follow manufacturer tightening procedure (do not over-tighten).
- After restart, check for seepage once the system reaches full operating pressure.
Related Products (Aqua Pool Supply)
- Pentair 170020 Tank Lid (Search)
- FNS Plus Tank Clamp O-Ring 39010200 (Search)
- FNS Plus Clamp Kit 190003 (Search)
- FNS Plus 36 Grid Assembly 59023500 (Search)
- Pentair 192019 Drain Plug Wrench (Search)
Maintenance Tips
- Keep the tank O-ring clean and lightly lubricated with pool-safe silicone lubricant to reduce pinching and leaks.
- Never open the filter until the pressure gauge reads zero and air has been fully relieved.
- If the filter is exposed to direct sun, shade can help extend the life of plastic tank components.
- Record your clean starting pressure after service so you can track when the filter needs cleaning.
Questions about returns? View our return policy.
Hours Of Operation:
Monday - Friday: 7:00 am to 5:00 pm Phoenix Time
Saturday: 8:00 am to 2:00 pm
Sunday: Closed
- We do not ship on Saturday or Sunday.
- Orders totaling more than $300 will require signature confirmation upon delivery.
- We process and prepare orders for shipment within 1 business day. Please note that many other pool supply retailers require 3–5 days of handling time before shipping.
- Orders placed after 1:00 pm Phoenix Time may not be eligible for same-day shipment.
- Expedited shipping options are available at checkout.
Return Policy:
- Products that are received damaged will receive a refund in store credit.
- Most products are eligible for return within 30 days of receipt, except where noted below.
- To initiate a return, please complete an RMA form prior to sending your item back.
- Original shipping costs are non-refundable and will be deducted from the return credit.
- Items returned missing accessories or original packaging, or that are not in the same condition as received, may be subject to a restocking fee of up to 100% depending on the condition of the item upon return.
- Some returns will be charged an automatic 15% restocking fee.
- We are unable to issue refunds for items that have been damaged or rendered inoperable due to installer error.
- Please complete the return form to receive your RMA number and return shipping label.
- Chemical products are not eligible for return under any circumstances.
- The Pentair Colorsync 618031 is not eligible for return.
- Pool cleaners are not eligible for return.
- Opened seals and o-rings are not eligible for return.
- Capacitors are not eligible for return.
- Plastic popup tools are not eligible for return.
- Automation components and circuit boards are not eligible for return.
- If a light is returned due to a reported malfunction and is found to be fully operational upon testing, return shipping costs and a restocking fee will be deducted from the refund.
- Orders refused at the time of delivery will be subject to the original shipping costs being deducted from the refund.
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