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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.
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711-4050 | Waterway Heater Union Gasket O-Ring | 1 1/2"
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CA P65 Warning: Cancer and reproductive harm. www.p65warnings.ca.gov
The OEM Waterway 711-4050 1½″ Heater Union Gasket O-Ring provides a reliable sealing solution for pool and spa heater unions with 1½″ connections. Fabricated from quality rubber material with an integrated ribbed O-ring edge, it matches typical dimensions of 1-5/8″ inside diameter and approx. 2-3/8″ outside diameter unions. This part replaces legacy numbers such as 711-4050B, 9175-41 and 90-423-1002, and is designed to work with a wide range of union fittings in heater and pump plumbing systems. By fitting this gasket properly during service, you maintain optimal system integrity, minimize leak risk, and prolong the operational lifespan of the union joint.
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Exact Union Replacement: Fits 1½″ unions (roughly 1-5/8″ ID and 2-3/8″ OD) to ensure correct contact and compression for effective sealing.
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Durable Rubber Design: Crafted from resilient rubber with a ribbed O-ring configuration to adapt to union surfaces and handle thermal and pressure cycles typical in pool/spa heater systems.
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Broad Compatibility: Suitable for unions across multiple spa and pool heater brands, replacing Waterway 711-4050, 711-4050B, and other cross-reference numbers like 9175-41 and 90-423-1002.
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Prevents Union Leaks: Targets common failure point where older or worn gaskets allow flow or weeping; installation restores tight seal at the union tailpiece.
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Easy Service Upgrade: Remove the union nut, clean mating surfaces, check the seat for corrosion or wear, and install this gasket to reinstate proper sealing during routine plumbing service.