Product Overview

This Heat Exchanger Kit is engineered for use with Pentair MasterTemp® and Max-E-Therm® 400K ASME BTU heaters. It includes the complete tubesheet coil assembly, sealing O-rings, insulation components, and adapter plates required for full core replacement. Designed for heaters manufactured after the factory design change date, this kit helps restore peak heating performance and extend the life of the heater unit.

Ideal For

• Service technicians repairing a MasterTemp or Max-E-Therm 400K heater whose core tube assembly is leaking, corroded, or failed.

• Pool owners seeking a cost-effective overhaul of their heater’s hydraulic core rather than replacing the entire unit.

• Installations where water-side corrosion or scale buildup has compromised the heat exchanger tubing.

• Heating systems where the heater cabinet, burner, blower and controls remain intact but the exchanger is the weak link.

Key Features

• Complete Coil / Tube-Sheet Replacement – provides a full core assembly rather than just partial parts, restoring full system performance.

• Includes Seals & Insulation – comes with O-rings, insulation kit and hardware to enable installation to factory specification.

• OEM Fit for 400K Heaters – compatible with models of MasterTemp and Max-E-Therm rated at 400K BTU, produced after the design change.

• Heavy-Duty Material Construction – built to withstand scale, corrosion and high-temperature water-flow conditions.

• Cost-Saving Repair Option – enables major heater component refresh at a fraction of full system replacement cost.

• Preserves Existing Equipment – keeps the original blower, burner assembly and wiring intact while refreshing the core.

Customer-Facing Q&A

Q: How do I know if this kit is right for my heater?
A: This kit is designed for MasterTemp® and Max-E-Therm® 400K heaters. Confirm your heater’s model number, manufacture date or design revision (the “HD” or “9-bolt” version) before ordering to ensure compatibility.

Q: Does this replace my whole heater?
A: No. It replaces the heat-exchanger or coil assembly inside your existing heater cabinet. The burner, blower and wiring remain in place if they are still functional.

Q: Is installation difficult?
A: It’s a technical repair—recommended for qualified technicians—with proper plumbing, wiring and pressure testing required.

Q: Will this improve my heater’s performance?
A: Yes. A worn or corroded exchanger reduces system efficiency, so replacing it helps restore full heating capacity and proper water flow.

Q: What other maintenance should I consider when installing this kit?
A: Inspect and clean burner assembly, ensure proper combustion, confirm water chemistry is addressed to prevent future corrosion, and verify all seals and insulation are properly installed.