HAR §12-223.1-10. the size of the boiler requires a pressure relief valve larger than NPS 4, two or more valves having the required combined capacity shall be used

When two or more valves are used on a boiler, they may be single, directly attached, or installed on a Y-base; (4) A threaded connection may be used for attaching a valve; (5) Pressure relief valves shall not be connected to an internal pipe in the boiler; (6) No shutoff valve of any description shall be placed between the pressure relief valve and the boiler or on discharge pipes between such valves and the atmosphere; (7) A discharge pipe shall be used. It shall be not less than the nominal size of the valve outlet. Where multiple valves relieve into a common discharge pipe, the cross-sectional flow area of the common discharge pipe shall be equal to or greater than the sum of the individual temperature and pressure relief valve discharge pipe areas. Discharge pipes shall be securely anchored and supported, as short and straight as possible and arranged as to avoid undue stress on the valve or valves. A union may be installed in the discharge piping close to the valve outlet. When an elbow is placed on a pressure relief valve discharge pipe, it shall be located close to the valve outlet downstream of the union to minimize reaction moment stress; (8) The discharge from pressure relief valves shall be so arranged that there will be no danger of scalding attendants. The pressure relief valve discharge shall be piped away from the boiler to a safe point of discharge, and there shall be provisions made for properly draining the piping. The size and arrangement of discharge piping shall be such that any pressure that may exist or develop will not reduce the relieving capacity of the relieving devices below that required to protect the boiler; and 223.1-30 3 5 5 9 §12-223.1-10 (9) Hot-water heating or hot-water supply heating boilers limited to a water temperature of 210 degrees Fahrenheit may have one or more NB capacity certified temperature and pressure relief valve(s) installed. The requirements of paragraphs (1) through (8) shall be met, except as follows: (A) A Y-type fitting shall not be used; and (B) If additional valves are used, they shall be temperature and pressure relief valves, and when the temperature and pressure relief valve is installed directly on the boiler with no more than four (4) inches maximum interconnecting piping, the valve may be installed in the horizontal position with the outlet pointed down. [Eff and comp 12/21/19; comp SEP - 0 2024 ] (Auth: HRS §397-4) (Imp: HRS §397-4) ### 12-223.1-11 Acceptable installation of temperature and pressure relief valves for potable water heaters. The following shall apply to the installation of temperature and pressure relief valves for potable water heaters: (1) Temperature and pressure relief valves shall be installed by either the water heater manufacturer or installer before a water heater is placed in operation; (2) Temperature and pressure relief valves shall be connected directly to a tapped or flanged opening in the top of the water heater, or to a fitting connected to the water heater by a short nipple; (3) Temperature and pressure relief valves shall be installed with their spindles upright and vertical with no horizontal connecting pipe, except when the temperature and pressure relief valve is connected directly on the water heater vessel with no more than four (4) inches maximum interconnecting piping, the 223.1-31 3559