The Ontario Building Code | Showers
(1) Except as provided for in Sentences (2) and (3), all valves supplying fixed location shower heads, shall be individually pressure-balanced or thermostatic-mixing valves, conforming to ASME A112.18.1 / CSA B125.1, "Plumbing Supply Fittings".
(2) An individually pressure-balanced or thermostatic-mixing valve shall not be required for showers if a single temperature water supply for such showers is controlled by a master thermostatic-mixing valve conforming to CSA B125.3, "Plumbing Fittings".
(3) Deck-mounted, hand-held, flexible-hose spray attachments are exempt from the thermal shock requirements of Sentence (1).
(4) pressure-balanced or thermostatic-mixing valves shall be,
(b) equipped with high-limit stops which shall be adjusted to a maximum hot water setting of 49°C.