Water Heater Temperature and Scald Protection
A new assisted living facility is being designed with a central water heating system. The plumbing code requires that hot water be delivered to fixtures at a temperature not exceeding 120°F to prevent scalding, but the facility wants to store water at 140°F to prevent Legionella growth. The design includes a master tempering valve that mixes hot and cold water to achieve 120°F at the fixtures. However, the facility is concerned that the tempering valve may fail and allow 140°F water to reach the fixtures. The code requires a high-limit temperature control or a thermostatic mixing valve that is listed and labeled to meet ASSE 1017. The contractor proposes a single tempering valve without a high-limit safety. The inspector must determine if this is acceptable under the code, considering the health and safety requirements for a facility with elderly occupants who are at higher risk of scald injuries. The code also requires that the water heater be equipped with a temperature and pressure relief valve.
1. Is a single tempering valve without a high-limit safety acceptable for this application? Explain the code requirements for scald protection in assisted living facilities.
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No, a single tempering valve without a high-limit safety is not acceptable. The plumbing code (e.g., IPC 607.1.2 or UPC 413.1) requires that tempered water be supplied to fixtures used for bathing, washing, and personal hygiene at a temperature not exceeding 120°F. For facilities with high-risk occupants such as assisted living, the code often requires additional protection. The typical requirement is a thermostatic mixing valve that is listed to ASSE 1017, which includes a high-limit safety that shuts off or reduces hot water flow if the outlet temperature exceeds a set point. A single valve without a high-limit safety could fail in the open position, allowing 140°F water to reach the fixtures, causing severe scalding. The code also requires that the water heater be equipped with a temperature and pressure relief valve, but that does not address scald protection at fixtures. The inspector should require a thermostatic mixing valve with a high-limit safety, or a master tempering valve with an additional high-limit switch that shuts off the hot water supply if the temperature exceeds 120°F. Additionally, point-of-use thermostatic mixing valves may be required at individual fixtures in high-risk areas.
2. What maintenance and testing requirements apply to the tempering valve to ensure continued safety?
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The code typically requires that thermostatic mixing valves be tested and maintained according to the manufacturer's instructions. The facility should have a maintenance program that includes regular testing of the valve's high-limit safety and temperature accuracy. The valve should be tested at initial installation and at least annually thereafter, or more frequently if required by the manufacturer. The test should verify that the outlet temperature does not exceed 120°F and that the high-limit safety functions properly. Records of testing should be kept. The inspector should verify that the facility has a maintenance plan and that the valve is accessible for testing and service. Additionally, the water heater's temperature and pressure relief valve should be tested annually.