The Pentair 474974 Union 1-1/2" Kit is the OEM replacement union package for the MasterTemp 125 pool heater, providing a complete set of 1-1/2" unions for heater plumbing connections. ⚠️ IMPORTANT: KIT LISTING — MULTIPLE PIECES INCLUDEDThis listing is a kit, not a single union. The 474974 includes the complete union package required for the MasterTemp 125 heater plumbing connections. Refer to your equipment manual to confirm the components included in this kit before ordering. ⚠️ IMPORTANT: HEATER COMPONENT — PROFESSIONAL INSTALLATION REQUIREDGas and electrical heater components must be serviced by a licensed pool professional or qualified HVAC technician. Do not attempt to service gas or high-voltage components without proper certification. The union kit provides the 1-1/2" union connections at the heater's water inlet and outlet ports. Unions allow the heater to be isolated and removed from the plumbing system without cutting pipe — a critical serviceability feature. Replacing deteriorated or leaking unions restores a watertight seal at the heater connections and maintains the ability to disconnect the heater cleanly for future service. Specifications Pentair Part Number 474974 Part Name Union 1-1/2" Kit Connection Size 1-1/2" Quantity Included Kit (2 unions with o-rings) Fits Into Brand Equipment Line Model / Part Number Notes Pentair MasterTemp 125 Heater — MasterTemp Series MASTERTEMP 125 — Compatibility is based on Pentair parts documentation and available OEM records. This is not an exhaustive list. For certainty, verify the part number in your equipment's manual or on the original part itself before ordering. Pro Tip When replacing the union kit, inspect the union O-rings and tail pieces at the same time. If the unions have reached the point of failure, the O-rings inside them are likely due for replacement as well. Confirm your heater's plumbing configuration — specifically the inlet and outlet port sizes — matches the 1-1/2" specification of this kit before ordering. If your MasterTemp is plumbed with 2" connections, a different union kit is required; consult your equipment manual or the part number on your existing unions.
