Hawaii Administrative Rules › Title 12 - DEPARTMENT OF LABOR AND INDUSTRIAL RELATIONS › Subtitle 8 - HAWAII OCCUPATIONAL SAFETY AND HEALTH DIVISION › Part 10 - BOILER AND PRESSURE VESSEL › Chapter 223.1 - HEATING BOILERS - STEAM HEATING BOILERS, HOT-WATER HEATING BOILERS, HOT-WATER SUPPLY BOILERS, AND POTABLE WATER HEATERS › Section 12-223.1-11 - Acceptable installation of temperature and pressure relief valves for potable water heaters

Current through June,
				  2024
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 installer or the manufacturer 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, to a fitting connected to
				  the water heater by a short nipple, to a Y-base, or to a valve-less header
				  connecting water outlets on the same heater;
(3) Temperature and pressure relief valves
				  shall be installed with their spindles upright and vertical with no horizontal
				  connecting pipe, except that, when the temperature and pressure relief valve is
				  installed directly on the water heater vessel with no more than four (4) inches
				  maximum interconnecting piping, the valve may be installed in the horizontal
				  position with the outlet pointed down. The center line of the temperature and
				  pressure relief valve connection shall be no lower than four (4) inches from
				  the top of the shell;
(4) No piping
				  or fitting used to install the temperature and pressure relief valve shall be
				  of nominal pipe size less than that of the valve inlet;
(5) When a potable water heater is fitted
				  with two or more temperature and pressure relief valves on one connection, this
				  connection shall have a cross-sectional area not less than the combined areas
				  of inlet connections of all the temperature and pressure release valves with
				  which it connects;
(6) When a
				  Y-base is used, the inlet area shall be not less than the combined outlet
				  areas;
(7) When the size of the
				  water heater requires a temperature and pressure relief valve larger than NPS 4
				  two or more valves having the required combined capacity shall be
				  used;
(8) When two or more valves
				  are used on a water heater, they may be single, directly attached, or installed
				  on a Y-base;
(9) A threaded
				  connection may be used for attaching a temperature and pressure relief
				  valve;
(10) Temperature and
				  pressure relief valves shall not be connected to an internal pipe in the water
				  heater or a cold-water feed line connected to the water heater;
(11) No shutoff valve of any description
				  shall be placed between the temperature and pressure relief valve and the water
				  heater or on discharge pipes between such valves and the atmosphere;
				  and
(12) The discharge from
				  temperature and pressure relief valves shall be so arranged that there will be
				  no danger of scalding attendants. When the temperature and pressure relief
				  valve discharge is piped away from the water heater to the point of discharge,
				  there shall be provisions for properly draining the piping and valve body. 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 water heater. The following shall
				  apply to discharge pipes:
(A) When a discharge
				  pipe is used, it shall be not less than the nominal size of the valve outlet,
				  and shall be as short and straight as possible, properly supported and so
				  arranged as to avoid undue stress on the valve. When an elbow is placed on a
				  temperature and pressure relief discharge pipe, it shall be located close to
				  the valve outlet; and
(B) 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.