Hayward manual air relief valve assembly DEX2420MAR2 for DE & cartridge vertical-grid filters — restores venting, prevents air loc

Hayward DEX2420MAR2 is a manual air-relief valve assembly designed to release trapped air from Hayward vertical grid-style DE and cartridge pool filters.

This compact replacement part restores safe, effective venting for Hayward Pro-Grid DE, SwimClear and Swimclear cartridge filters, helping the filtration system run efficiently by letting air escape before normal operation. Built in the United States, the assembly is a straightforward service component for pool owners and technicians maintaining compatible Hayward vertical filters. Some installations may also require the DEX2420Z8A O-ring kit (two O-rings) to ensure a leak-free seal.

How do I know this assembly fits my Hayward filter?

Confirm fit by matching your filter model to the compatible list: Pro-Grid DE models and SwimClear/Swimclear cartridge filters that use the vertical grid-style top vent. Check the filter top for existing manual relief hardware geometry and thread style.

• Compatible with Hayward Pro-Grid DE filters.
• Works on SwimClear and Swimclear cartridge vertical-grid filters.
• Compare threads and valve location to your current relief valve.
• May need DEX2420Z8A O-ring kit for proper sealing.

What does the manual air relief assembly do for pool performance?

The valve helps purge trapped air from the filter tank before the pump runs at normal pressure, preventing loss of prime, noisy operation, and pressure spikes. Regularly venting air improves circulation consistency and protects pump and filter components from cavitation and stress.

• Allows trapped air to escape safely from the filter head.
• Helps maintain steady pump prime and flow rate.
• Reduces noise and pressure fluctuations during start-up.
• Extends life of filter grids and pump by preventing cavitation.

What installation or replacement steps should I follow?

Installation is typically straightforward: turn off the pump, relieve tank pressure, remove the old valve, inspect the mounting surface and threads, fit the new assembly, and test for leaks. Use a compatible O-ring if the original is worn or missing for a reliable seal.

• Shut off pump and open filter drain to relieve pressure.
• Remove the old relief valve and clean mating surfaces.
• Install new DEX2420MAR2 assembly, replace O-rings if needed.
• Restart system and check for proper venting and leaks.

Are replacement parts or accessories required?

Many swaps are direct replacements, but aging filters often need fresh sealing hardware. The DEX2420Z8A O-ring kit (set of 2) is commonly recommended to ensure a tight fit and prevent leaks; check your valve and filter head for wear before finalizing installation.

• DEX2420Z8A O-ring kit may be required for a leak-free fit.
• Inspect existing threads and gasket surfaces for damage.
• Use compatible lubricants sparingly on O-rings if installing new seals.
• Keep manufacturer instructions and part numbers on hand during maintenance.

Who is this for: pool owners, maintenance technicians, and service shops that use Hayward vertical grid-style filters and need a reliable manual air-relief solution. If you maintain Pro-Grid DE or SwimClear cartridge systems and want a direct-fit replacement made in the United States, the DEX2420MAR2 provides a durable option to restore proper venting. For older filters, have the DEX2420Z8A O-ring kit available to complete the repair and ensure a leak-tight seal.