TL;DR: Replacing the Pentair FNS SMBW Clean and Clear pool air relief valve takes 15–20 minutes and requires minimal tools. This valve releases trapped air from the filter system, ensuring optimal filtration efficiency. Replacement restores proper air venting, prevents pressure buildup, and maintains peak filter performance. Signs needing replacement include leaking valve, difficulty opening/closing, and incomplete air release.
SEO Summary: This 2026 guide provides complete step-by-step instructions for replacing Pentair FNS SMBW Clean and Clear pool air relief valve including tools, removal, installation, and testing procedures.
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Table of Contents
Component Overview and Function
The Pentair FNS SMBW Clean and Clear pool air relief valve is a critical component for removing trapped air from cartridge filter systems.
Component Description:
- Filter Type: Pentair Clean & Clear cartridge filters
- Models: FNS, SMBW series filters
- Type: Manual air relief valve
- Material: Durable plastic (chemical-resistant)
- Location: Top of filter tank
- Operation: Manual twist-open valve
Function and Purpose:
- Releases trapped air from filter tank
- Prevents air pockets reducing filtration efficiency
- Allows complete filter priming after cleaning
- Maintains optimal water flow through filter
- Prevents pressure buildup from trapped air
- Essential for proper filter operation
Compatible Filters:
- Pentair Clean & Clear cartridge filters
- FNS Plus D.E. filters
- SMBW series filters
- Various Clean & Clear models (verify compatibility)
- Works with Clean and Clear 75 sq ft filters
- Check filter model number for exact match
Why This Component Matters:
- Trapped air reduces filtration efficiency 20–30%
- Air pockets cause uneven water distribution
- Incomplete air release leads to cloudy water
- Proper venting maintains design flow rate
- Prevents premature cartridge fouling
- Small investment ($15–$30) prevents efficiency loss
Signs You Need Replacement
Recognizing failure symptoms helps maintain filter efficiency and prevents air-related problems.
Valve Leaks:
- Water dripping from valve when closed
- Water spray when opening valve
- Constant seepage around valve body
- Puddles on filter top
- Valve won't seal completely
- Visible cracks in valve body
Operational Issues:
- Valve difficult to open or close
- Valve handle broken or stripped
- Valve stuck in open or closed position
- Incomplete air release when opened
- Valve requires excessive force to operate
- Grinding or gritty feel when turning
Performance Problems:
- Air trapped in filter (visible in sight glass if equipped)
- Reduced water flow despite clean cartridges
- Higher than normal pressure gauge reading
- Cloudy water despite proper chemistry
- Difficulty priming filter after cleaning
- Uneven cartridge loading (some dirty, some clean)
Physical Damage:
- Cracked or broken valve body
- UV degradation (brittle, chalky appearance)
- Chemical damage (discoloration, pitting)
- Missing or damaged O-rings
- Stripped threads
- Warped or deformed components
Tools and Materials Needed
Minimal tools required for this straightforward replacement.
Required Tools:
- Adjustable wrench or channel locks
- Small flathead screwdriver
- Clean rags or towels
- Bucket for water drainage
- Safety glasses
Required Materials:
- Pentair FNS SMBW air relief valve (replacement)
- Teflon tape (for threads)
- Replacement O-ring (if not included)
- Silicone lubricant (pool-safe)
- Clean water for rinsing
Optional But Recommended:
- Replacement air relief valves 2-pack for backup
- Calcium remover solution
- Small brush for cleaning threads
- Camera for documentation
- Replacement pressure gauge if also damaged
Preparation and Safety
Proper preparation ensures safe, efficient replacement.
System Shutdown:
- Turn off pool pump at breaker
- Set multiport valve to "Closed" position (if applicable)
- Release system pressure through air relief valve
- Verify pump completely off before proceeding
- Wait 2–3 minutes for system to fully depressurize
Pressure Release:
- Slowly open air relief valve
- Allow all air and water to escape
- Keep face and hands away from valve opening
- Have towel ready for water spray
- Ensure no pressure remains in filter tank
Workspace Preparation:
- Clear area around filter top
- Place bucket under valve for drainage
- Have all tools within reach
- Ensure adequate lighting
- Protect surrounding areas from water
Safety Considerations:
- Wear safety glasses (protect from water spray)
- Ensure system fully depressurized
- Avoid contact with pool chemicals on components
- Work carefully to prevent filter damage
- Keep children and pets away from work area
Removing Old Valve
Careful removal prevents damage to filter tank threads.
Valve Removal Procedure:
- Ensure system fully depressurized
- Grip valve body with adjustable wrench
- Turn counterclockwise to loosen
- Support filter tank to prevent stress
- Unscrew valve completely by hand once loose
- Lift valve straight out
Dealing with Stuck Valves:
- Apply penetrating oil if valve stuck (let sit 15 minutes)
- Use larger wrench for better leverage
- Tap valve gently with rubber mallet to break seal
- Heat valve body slightly with heat gun (plastic safe temperature)
- Never force excessively (can crack filter tank)
- Consider professional help if severely stuck
Thread Inspection and Cleaning:
- Inspect filter tank threads for damage
- Clean threads with small brush
- Remove calcium deposits or debris
- Check for cracks around threaded opening
- Rinse threads with clean water
- Dry threads thoroughly before installation
Old Valve Inspection:
- Examine valve for failure cause
- Check O-ring condition
- Note any cracks or damage
- Compare with new valve for verification
- Determine if preventable failure
Installing New Valve
Proper installation ensures leak-free operation and long valve life.
Valve Preparation:
- Remove new valve from packaging
- Inspect for shipping damage
- Verify correct model for your filter
- Check O-ring included and properly seated
- Clean valve if needed
Thread Preparation:
- Apply 2–3 wraps of Teflon tape to valve threads
- Wrap in clockwise direction (direction of installation)
- Ensure tape doesn't cover first thread
- Press tape firmly into threads
- Trim excess tape
O-Ring Installation:
- Inspect O-ring for damage
- Apply silicone lubricant to O-ring
- Install O-ring in valve groove if not pre-installed
- Ensure O-ring seated properly
- Verify O-ring not twisted or pinched
Valve Installation:
- Thread valve into filter tank by hand
- Turn clockwise until hand-tight
- Ensure valve threading straight (not cross-threaded)
- Use wrench for final 1/4–1/2 turn only
- Don't over-tighten (cracks valve or tank)
- Verify valve oriented properly (handle accessible)
Final Checks:
- Ensure valve fully seated
- Check for visible gaps or misalignment
- Verify valve operates smoothly
- Confirm O-ring visible in groove
- Wipe exterior clean
Testing and Verification
Thorough testing ensures proper installation and function.
System Startup:
- Restore power to pump
- Open multiport valve to "Filter" position
- Start pump and allow system to pressurize
- Monitor pressure gauge reading
- Listen for unusual sounds
Air Release Testing:
- Slowly open air relief valve
- Verify smooth air release
- Check for water spray (indicates air purged)
- Close valve when steady water stream appears
- Verify valve closes completely
- Check for leaks around valve
Leak Inspection:
- Inspect valve body for leaks
- Check O-ring seal area
- Verify no water seepage from threads
- Look for drips or spray
- Allow system to run 10–15 minutes
- Recheck all seal points
Operation Verification:
- Open and close valve several times
- Verify smooth operation without sticking
- Check that valve seals properly when closed
- Ensure no water leaks from valve
- Confirm normal pressure gauge reading
- Verify proper air venting sound
Performance Checks:
- Verify filter pressure normal for clean cartridges
- Check water flow at return jets
- Ensure no air bubbles in return water
- Confirm pump maintains prime
- Monitor system for 15–20 minutes
- Recheck valve operation after initial run
Maintenance Tips
Regular maintenance extends valve life and ensures optimal filter performance.
Routine Maintenance:
- Operate valve monthly to prevent sticking
- Release air after each filter cleaning
- Inspect valve for leaks during filter maintenance
- Clean valve exterior to remove calcium buildup
- Lubricate O-ring annually with silicone lubricant
- Check valve operation before each swim season
Cleaning Procedure:
- Wipe valve exterior with damp cloth
- Remove calcium deposits with vinegar solution
- Rinse thoroughly with clean water
- Dry completely before operating
- Don't use abrasive cleaners (damage plastic)
Preventive Measures:
- Maintain proper water chemistry (prevents corrosion)
- Don't over-tighten valve during operation
- Release pressure before opening valve
- Protect valve from direct sunlight when possible
- Inspect O-ring condition during filter cleaning
- Replace valve every 3–5 years regardless of condition
When to Replace vs Repair:
- Replace: Cracked body, stripped threads, broken handle
- Repair: Leaking O-ring (replace O-ring only)
- Replace: Valve over 5 years old
- Replace: Valve requires excessive force to operate
- Keep spare valve on hand for quick replacement
Conclusion and Key Takeaways
Replacing the Pentair FNS SMBW Clean and Clear pool air relief valve takes 15–20 minutes and requires minimal tools. This valve is essential for removing trapped air from the filter system, ensuring optimal filtration efficiency and water clarity. Proper installation and regular maintenance prevent leaks, maintain filter performance, and extend valve lifespan.
Essential Takeaways:
- Air relief valve removes trapped air from filter system
- Replace when leaking, stuck, or difficult to operate
- Turn off pump and depressurize system before starting
- Slowly open valve to release all pressure
- Use wrench to remove old valve (turn counterclockwise)
- Clean filter tank threads thoroughly before installation
- Apply 2–3 wraps of Teflon tape to new valve threads
- Lubricate O-ring with silicone lubricant
- Hand-tighten valve, then 1/4–1/2 turn with wrench
- Don't over-tighten (cracks valve or filter tank)
- Test valve operation after installation
- Verify no leaks at valve body or O-ring
- Operate valve monthly to prevent sticking
- Replace valve every 3–5 years for reliability
- Use quality air relief valve assemblies for replacements
- Maintain filters with replacement cartridge elements
- Monitor with accurate filter pressure gauges
- Keep spare air bleed tubes on hand
- Small investment ($15–$30) prevents 20–30% efficiency loss
- Shop quality replacement parts from our pool parts collection
Follow these replacement steps for professional-quality results. Proper air relief valve maintenance ensures years of efficient filter operation and crystal-clear pool water. The small investment in time and parts prevents costly efficiency loss and maintains optimal pool system performance.
