Pentair 77707-0234 Tube Sheet Coil Assembly Replacement Kit Pool and Spa Heater

The Pentair 77707-0234 Tube Sheet Coil Assembly Kit is a premium OEM replacement component engineered for high-capacity residential or light commercial pool and spa heater systems. Intended specifically for the MasterTemp 400NA/400LP and Max-E-Therm 400K (or equivalent) heater series manufactured before January 2009, this kit addresses one of the most critical internal service components—the tube-sheet coil assembly which transfers heat from the combustion chamber to the pool water. Over time, the original exchanger’s tubesheet area may suffer from corrosion, scaling, erosion or fatigue—leading to decreased heating efficiency, elevated stack gas temperature, reduced flow, or outright failure. The 77707-0234 kit restores factory-level performance by providing a precision-matched tube sheet and coil assembly built from corrosion-resistant cupro-nickel alloy, known for its durability in harsh marine and aquatic equipment conditions. In addition to the core assembly, the kit includes a complete O-ring gasket set and high-temperature RTV silicone sealant to ensure proper sealing and prevent leaks. Professional installation helps return your heater’s output to its original design parameters. Once installed, the heater regains its ability to transfer heat effectively, maintain optimum water temperature, prevent premature shutdowns or safety trip outs, and extend service life—avoiding the cost of a full heater replacement. This makes the 77707-0234 kit a smart investment for service technicians, pool dealers and proactive homeowners managing mature heater systems. Designed for equipment-pad environments, the assembly resists pool chemical exposure, humid conditions, thermal cycling and equipment vibration. Whether you’re repairing a heater showing symptoms of reduced output, high exhaust temperatures, or internal scaling, this kit provides OEM reliability and long-term durability. For anyone operating a Pentair or Sta-Rite 400 K BTU heater built prior to January 2009, the Pentair 77707-0234 Tube Sheet Coil Assembly Kit offers a targeted, high-performance repair solution—restoring efficiency, protecting your investment and delivering years of service in demanding poolside installations.