The Ontario Building Code | Relief Valves
18.104.22.168. Relief Valves
(1) Every pressure vessel that is part of a plumbing system or connected to a plumbing systemshall be equipped with a pressure relief valve designed to open when the water pressure in the tank reaches the rated working pressure of the tank, and so located that the pressure in the tank shall not exceed 1 100 kPa or one-half the maximum test pressure sustained by the tank, whichever is the lesser.
(a) located within the top 150 mm of the tank, and
(4) Every indirect service water heatershall be equipped with,
(a) a pressure relief valve, and
(b) a temperature relief valve on every storage tank that forms part of the system.
(a) be of a sizeat least equal to the size of the outlet of the valve,
(b) be rigid, slope downward from the valve, and,
(i) terminate with an indirect connection above a floor drain, sump or other safe location, with an air break of not more than 300 mm, or
(ii) terminate at a distance not less than 150 mm and not more than 300 mm from a floor and discharge vertically down,
(c) have no thread at its outlet, and
(d) be capable of operating at a temperature of not less than 99°C.
(6) The temperature relief valve required in Clause (4)(b) shall,
(a) have a temperature sensing element located within the top 150 mm of the tank, and
(7) No shut-off valve shall be installed on the pipe between any tank and the relief valves or on the discharge lines from such relief valves.