4.4 Water Valves, Shutoffs, Manifolds, & Hot Water Distribution (UPC 606, 609.11; WA 210.0 and 609.11)

Valves Required by UPC 606

Parallel (manifold) distribution systems

Washington's amendment to 606.5 adds:

• A parallel water distribution system (a manifold with individual lines to each fixture) must have a control valve either immediately ahead of each fixture or at the manifold, and each manifold valve must be identified with the fixture it supplies.
• Where the manifold is in an attic, crawl space, or other location that is not accessible, a separate shutoff valve is required immediately ahead of each fixture or appliance.
• Washington's 610.4 amendment adds that listed parallel systems are installed per their listing. The UPC also requires that velocity limits never be exceeded.

Unions and Connectors Near Equipment

• 609.5: Unions go in the water supply piping within 12 inches of regulating equipment, water heaters, conditioning tanks, and similar equipment that must be removed for service.
• 604.5: Flexible water connectors must be readily accessible.
• 603.4.5: Backflow preventers on hot water over 110°F must be designed to operate at that temperature.

Hot Water: Definitions and Temperature Limits

• Washington 210.0: "Hot water" is water at a temperature exceeding or equal to 100°F. The unamended 2015 UPC definition is 120°F, so this is a Washington difference worth memorizing.
• Point-of-use limits (Section 2.2): showers and tub-showers use ASSE 1016 valves with stops at 120°F, tub fillers and public lavatories use ASSE 1070 devices at 120°F, and bidets are limited to 110°F. The water heater thermostat never counts as the control.
• 417.5: With two handles, hot is on the left.

Hot Water Pipe Insulation

• Washington 609.11: "Domestic water piping within commercial buildings shall be insulated in accordance with Section C403.2.8 and Table C403.2.8 or Section C404.6 of the Washington State Energy Code, as applicable." In Washington, commercial hot water pipe insulation thickness comes from the energy code, not the UPC.
• Washington 312.6: All hot and cold water pipes installed outside the conditioned space must be insulated. The 2015-edition amendment specified a minimum of R-3 (Section 1.3).
• For reference, the unamended UPC 609.11.2 ties insulation wall thickness to pipe diameter: at least the pipe's diameter for pipe up to 2 inches, and 2 inches for larger pipe. Washington replaces 609.11 with the energy code reference.

Hot Water Recirculation

Long runs from a water heater waste water and energy while users wait for hot water. Designers answer with a recirculation loop (supply main, return line, and pump) or with heat trace. The 2015 UPC places recirculation rules, including pump controls and maximum hot water volume, in Appendix L, Sustainable Practices. Washington adopts only Appendices A, B, and I of the UPC. In Washington, recirculation controls and hot water system efficiency are therefore energy code requirements, not UPC exam content.

Good practice on any loop:

1. Check valve on the return near the heater, so cold water cannot enter the return and cross over into the hot supply when fixtures open.
2. Balancing valves on each return branch in multi-riser systems, so the nearest loop does not short-circuit the flow.
3. Pump controls (timer, aquastat, or demand activation) as the energy code requires, rather than 24-hour operation.
4. Insulate supply and return piping as the energy code requires.
5. Isolation valves and unions at the pump for service (606.6, 609.5).

Worked Scenario: A Four-Unit Apartment Building

A four-unit building on one lot is served by one meter.

• 606.2: Put a fullway valve on the discharge side of the meter. Because the four units are in one building, one building valve serves the building. A second building on the same premises would need its own fullway valve.
• 606.3: Each unit needs accessible shutoff valves inside that unit, so one apartment can be isolated for repairs.
• 606.5: Put control valves (angle stops) ahead of each lavatory, water closet, sink, dishwasher, clothes washer, and water heater. Every slip-joint fixture supply needs one.
• Manifold option: If each unit uses a PEX manifold in an accessible closet with valves labeled by fixture, the stops may be at the manifold. If the manifold is in the attic, a separate shutoff is required at each fixture.