Red PEX hot-water return branch with a bronze circulator pump and two brass ball valves tying into the side of an unbranded commercial storage water heater, copper risers clipped to a grey block mechanical-room wall

What US Plumbing Code Requires of a Hot-Water Return Leg: UPC vs IPC vs ASHRAE 90.1, and Which Listed Pipe You May Actually Use for It

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No US plumbing code orders you to build a hot-water return leg. IPC 2024 Section 607.2 caps developed length at 50 feet and counts recirculating piping as a source of hot water; the sentence requiring a dedicated return pipe sits in the energy code, at IECC 2024 Section C404.6.1. Which listed pipe may form it

What US Plumbing Code Requires of a Hot-Water Return Leg: UPC vs IPC vs ASHRAE 90.1, and Which Listed Pipe You May Actually Use for It Lire plus "