711-4050 | Waterway Heater Union Gasket O-Ring | 1 1/2"

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.

Highlights

• 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.

• 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. 

• 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.

• Prevents Union Leaks: Targets common failure point where older or worn gaskets allow flow or weeping; installation restores tight seal at the union tailpiece. 

• 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.

Additional Info

If you’re replacing the OEM Waterway 711-4050 1½″ Heater Union Gasket O-Ring, this section helps you confirm fitment, identify compatible unions, and troubleshoot leak issues before buying in store. This gasket supports 1½″ heater and pump union connections and replaces older numbers such as 711-4050B, 9175-41 and 90-423-1002.

Identifying the Correct 1½″ Waterway Union Gasket

This gasket is designed for unions with an inside diameter around 1-5/8″ and an outside diameter near 2-3/8″. Its ribbed O-ring profile matches Waterway heater and pump unions commonly used in residential pool/spa plumbing.

How to check if my heater union uses the Waterway 711-4050 gasket

Can I bring my old union gasket into the store to match the correct size

Does this gasket replace earlier Waterway numbers like 711-4050B

How to measure my union ID and OD to verify a proper 1½″ fit

What signs indicate my existing union gasket has flattened or failed

Installing the Gasket and Preventing Heater Union Leaks

A proper seal requires seating the ribbed edge evenly against the tailpiece, checking for debris, and tightening the union by hand before final snugging. Correct installation prevents weeping, dripping or suction leaks.

How to install the 711-4050 gasket so the ribbed edge seals correctly

Why unions may still leak even after installing a new gasket

Can I buy a new union tailpiece in store if mine is cracked or warped

What to check if the heater union drips only when the pump starts

Whether lubrication helps seat this style of Waterway gasket

Maintaining Long-Term Union Performance

Replacing worn gaskets reduces heater wear, prevents scale stains and ensures steady system pressure. Fresh gaskets restore compression and keep fittings tight during temperature and pressure cycles.

How often should I replace union gaskets on above-ground or in-ground systems

Can I buy matching Waterway unions in store if my fittings no longer align

What causes heater unions to lose seal after seasonal startup

How to test for small weeping leaks around a freshly installed gasket

When to replace the entire union assembly instead of only the gasket