The Pentair Kit Eti Hx Union Adapternull | 476106 is a Heat Exchanger Union Adapter Kit specifically designed for select Pentair ETi series pool and spa heaters.  

Here's a breakdown of what this kit likely includes and its purpose:

Key Features:

• Genuine Pentair Part: Ensures proper fit and compatibility with your Pentair ETi heater.
• Heat Exchanger Connection: This kit provides the necessary union adapters to connect the plumbing to the heat exchanger of your heater.
• Union Fittings: Union fittings allow for easy disconnection and reconnection of plumbing lines, which is essential for maintenance, servicing, or winterization of the heater.  
• Seals and O-rings: The kit will typically include the necessary O-rings and seals to ensure a watertight connection between the union adapters and the heat exchanger.
• Durable Materials: Constructed from materials designed to withstand the heat and chemical environment associated with pool and spa systems.

Benefits:

• Facilitates Easy Servicing: Unions allow for quick removal of the heater without cutting pipes.
• Ensures Watertight Connections: Prevents leaks in the plumbing connections to the heat exchanger.
• Proper Fit and Function: Using a genuine Pentair kit guarantees compatibility with your ETi heater.
• Essential for Installation or Replacement: This kit is necessary when installing a new ETi heater or replacing the heat exchanger.

In summary, the Pentair Kit Eti Hx Union Adapternull | 476106 is a crucial set of fittings required to properly connect the plumbing to the heat exchanger of your Pentair ETi series pool and spa heater, ensuring a secure and leak-free installation that allows for easy maintenance.