Magic Plastics 0121108025 2.5" Hot Tub Heater Union Split Nut FBT Large Flange

Easily repair your cracked or leaking hot tub heater union without cutting plumbing using the Magic Plastics 0121108025 2.5" Heater Union Split Nut. Designed as a direct drop-in replacement, this split nut features a Female Buttress Thread (FBT) and a large flange specifically engineered to fit metal heater housings. It includes the necessary assembly screws, allowing you to secure the connection quickly and get your spa back up and running.

🚩 PRO TIP

Because plumbing sizes are based on internal pipe diameter rather than physical thread measurements, a 2.5" split nut actually measures approximately 3-9/16" (3.56") across the inside threads. Always measure the outside diameter of your heater housing threads before ordering to ensure compatibility. This fitting does not fit Jandy AquaPure 1400 systems.

PRODUCT FEATURES

• No-Cut Repair: Split design allows you to replace a broken union nut without having to cut and re-glue PVC pipes.
• Large Flange Design: Specifically engineered with a large flange to securely grip metal heater housings.
• Durable Construction: Made from high-quality, impact-resistant plastic to withstand hot tub temperatures and chemicals.
• Hardware Included: Comes complete with the two assembly screws needed to secure the split halves together.
• Universal Compatibility: Fits standard 2.5" heater tailpieces (measuring ~3-9/16" across the threads) found on many Balboa, Gecko, and generic spa control systems.

TECHNICAL SPECIFICATIONS

• Brand: Magic Plastics
• Part Number: 0121108025
• Part Type: Heater Union Split Nut
• Nominal Plumbing Size: 2-1/2" (2.5")
• Actual Inside Thread Diameter: Approx. 3-9/16" (3.56")
• Thread Type: Female Buttress Thread (FBT)
• Flange Style: Large Flange (for metal housings)
• Color: Black
• UPC/GTIN: 724137624471

FREQUENTLY ASKED QUESTIONS

How do I know if I need a 2" or 2.5" split nut?

Spa plumbing sizes refer to the internal diameter of the PVC pipe, not the nut itself. A 2.5" split nut will measure approximately 3-9/16" (3.56") across the inside threads. If your inside thread measurement is closer to 3", you need a 2" split nut instead.

Does this include the heater gasket/o-ring?

No, this listing is for the split nut and assembly screws only. If your heater union is leaking, it is highly recommended to replace the 2.5" heater gasket at the same time to ensure a watertight seal.

Will this fit a Jandy AquaPure salt cell?

No. While it looks similar, this specific Magic Plastics split nut (0121108025) does not fit the Jandy AquaPure 1400 or 700 salt cell housings. It is designed for standard hot tub heater tubes.

Do I need to glue this fitting?

No glue is required. The split nut simply clamps over your existing heater tailpiece flange and screws together, pulling the tailpiece tight against the heater housing when threaded on.

What does "FBT" mean?

FBT stands for Female Buttress Thread. Buttress threads are flat on one side and angled on the other, designed specifically to withstand the high thrust loads found in pressurized pool and spa plumbing connections.

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