Find your parts diagram
Sticker on the pump body (the part with the basket), not on the motor. Motor labels from Century, A.O. Smith or Regal won't match parts.
Label on the side of the tank near the base. Size is in sq ft, e.g. 420 sq ft = C4030 or CCP420.
Rating plate inside the front access panel. Note the BTU and gas type (NG or LP).
Molded into the body or printed on top. Robotic cleaners: on the power supply.
Still not sure? Call (818) 818-6559 and we'll find it for you.
711-4030 | Waterway Heater Union Gasket O-Ring | 2"
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The Waterway 711-4030 is a precision-engineered ribbed gasket/O-ring designed to ensure a watertight seal at 2″ heater union connections. Manufactured by Waterway Plastics, this part is compatible with standard 2″ and 2½″ heater unions and tailpieces, making it ideal for both pool and spa heater applications. With an inner diameter of approximately 2-1/8″ and an outer diameter around 2-15/16″, it fits snugly between union flanges to prevent leaks and maintain system integrity. Crafted from durable elastomeric material that stands up to high temperature, chemical exposure and repeated service cycles, it serves as a reliable replacement gasket when performing maintenance or heater replacements.
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Precise Fit for 2″ Unions: Engineered with a ~2-1/8″ ID and ~2-15/16″ OD to match 2″ heater union connections.
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Ribbed O-Ring Profile: Features a raised sealing rib for enhanced compression and tighter sealing under union pressure.
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High Durability Materials: Built to resist pool and spa chemicals, heat and plumbing pressure fluctuations to reduce leak risk.
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OEM-Compatible Quality: Produced by Waterway to align with original equipment standards and ensure compatibility in heater systems.
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Maintenance-Friendly Replacement: A simple gasket swap when servicing tailpieces or heater unions helps prevent downtime and costly leaks.
If you’re replacing the Waterway 711-4030 2″ Heater Union Gasket/O-Ring, this guide explains how to confirm fitment, identify compatible heater unions and troubleshoot leak issues before buying in store. This ribbed gasket fits standard 2″ and 2½″ Waterway-style heater unions and supports dependable sealing in pool and spa systems.
Confirming the Correct 2″ Waterway Heater Union Gasket
The 711-4030 is engineered with an inner diameter of about 2-1/8″ and an outer diameter around 2-15/16″. It fits snugly between heater union flanges and replaces worn gaskets that cause drips or weak seals.
How to check if my heater union uses the Waterway 711-4030 gasket
Can I bring my old gasket into the store to match the correct 2″ size
Does this gasket fit 2″ and 2½″ Waterway heater tailpieces
How to measure my union dimensions to confirm 711-4030 compatibility
What signs indicate my old heater gasket has flattened or cracked
Installing the Gasket and Preventing Heater Union Leaks
Correct installation requires aligning the ribbed sealing edge inside the union groove, tightening the nut evenly and ensuring the tailpiece surface is clean. This avoids pressure-cycle leaks and startup drips.
How to position the ribbed side of the 711-4030 gasket for best sealing
Can unions still leak even after installing a new Waterway gasket
Can I buy a replacement union nut or tailpiece in store if mine is warped
Why some heater unions only leak when the pump first kicks on
Whether using lubricant helps seat the ribbed gasket properly
Maintaining Long-Term Union Performance
A fresh gasket restores compression, protects heater threads and prevents water loss during pressure changes. Regular inspection reduces failure risk and extends the life of the union assembly.