scope:

This standard is for water heaters that control the outlet temperature to specific limits and are installed within a hot water distribution system but not at point-of-use.

Description

The water heater shall consist of a heat exchanger, a cold water inlet connection, a hot water outlet connection, and a means for precisely governing the outlet temperature. The water heater controller shall be listed to the appropriate electrical safety standard in accordance with the water heater category. 

Maximum Working Pressure

The maximum working pressure of the water heater shall be at least 160 psi (1103 kPa) for water heaters in compliance with the ASME Boiler and Pressure Vessel Code, or at least 150 psi (1034 kPa) for water heaters in compliance with standards such as UL 174, UL 499, UL 1453, ANSI Z21.10.1 / CSA 4.1, or ANSI Z21.10.3 / CSA 4.3. 

Inlet Water Temperature Range

The water heater shall be capable to operate with a cold water inlet temperature range of 45°F to 105°F (7.2°C to 40.6°C). 

Outlet Water Temperature Range

The water heater shall be capable of supplying the domestic hot water distribution system with a minimum adjustable hot water setpoint range of 105°F to 125°F (40.6°C to 51.7°C) when the incoming temperature is between 45°F and 105°F (7.2 °C and 40.6 °C). 

Maximum Flow Rates

The maximum flow rates of the water heater at given temperature rises shall be obtained from the water heater technical datasheet.

Compliance with Safety Standards

Water heaters shall conform to the safety requirements of the applicable water heater standards. Electrical controls shall comply and be categorized as operating controls with Class A control functions per UL 60730-1 and UL 60730-2-9, or comply with the applicable requirements of UL 499.