The Raypak R185A/R185B CuNi Upgrade Tube Bundle (010859F) is a Raypak heater water-side replacement component used to support heat transfer, water routing, and reliable heater operation in the compatible model listed. Heat exchangers, tube bundles, and header assemblies are critical parts of the heater system because they manage water movement through the heating area while withstanding heat, pressure, and pool or spa water chemistry. This part should be matched carefully to the heater model and part number 010859F to avoid fitment issues with headers, flue collectors, bypass components, and surrounding cabinet parts.This item is a practical choice for repairs involving leaking, restricted, corroded, or freeze-damaged water-side components. The cupronickel configuration noted in the title helps identify the correct replacement style for the specific application. Proper installation, sealing, and pressure testing are recommended before returning the heater to service. Designed for the Raypak model/application shown in the product name Supports proper water flow through the heater heat-transfer section Useful for leak repairs, corrosion replacement, or major heater rebuilds Match material type, model series, and header configuration before ordering Verify part number 010859F against the existing Raypak component
