4154021 1.5' FBT Pool & Spa Union Heater Split Nut (Without Screws) Restore a secure, leak union connection on your pool or spa heater with this directfit split nut designed for 1.5' FBTstyle unions. The split nut format makes replacement and service faster and easier than replacing the entire union assembly, and the part is identified by model number 4154021 for straightforward identification. Key benefits Fast, targeted : only the worn or damaged nut portion of the union instead of the whole fitting to save time and money. Precise fit for 1.5' FBTstyle heater unions: Intended for use where a 1.5' FBT union nut is required, providing proper alignment and secure connection. Simplifies maintenance: Split design permits installation around existing piping and hoses without full disassembly of the plumbing run. Clear information: Model number 4154021 makes it easy to match the correct replacement part. Key attributes Model: 4154021 Size: 1.5' nominal union nut Type: Split nut for union connections Application: Pool and spa heater unions (FBTstyle) Hardware: Supplied without screws — mounting hardware must be provided separately Functionality and compatibility Designed to accept and secure the union union halves on 1.5' FBTstyle heater connections. Split construction allows the nut to be fitted around existing piping where a onepiece nut cannot be removed. Intended for use with compatible union faces and sealing elements; confirm match with your existing union components before installation. Screws or fasteners are not included; use the correct length and thread type as required by your union assembly. Common use cases a cracked, stripped, or worn union nut on a 1.5' pool or spa heater without replacing the entire union assembly. Perform routine heater maintenance where the nut must be swapped quickly to restore a tight, leak connection. Keep as a service part in a technician's kit to enable onsite repairs for FBTstyle 1.5' unions. Installation notes Confirm that this split nut matches the profile and thread type of your existing 1.5' FBTstyle union. Screws/fasteners are not included — retain the original hardware if reusable or source the correct replacements before starting the . Inspect sealing surfaces and any Orings or gaskets during reassembly and if worn to ensure a reliable seal. Choose part 4154021 when you need a straightforward, costeffective replacement split nut for 1.5' FBTstyle pool and spa heater unions.