Abstract: A mixing valve includes a manifold, a temperature-responsive device, a first by-pass mechanism, and a second by-pass mechanism. The manifold defines a cold fluid inlet, a hot fluid inlet, a fluid outlet in fluid communication with the cold fluid inlet and the hot fluid inlet, and a mixing chamber in fluid communication with the cold fluid inlet, the hot fluid inlet, and the fluid outlet. The temperature-responsive device is capable of regulating the relative volumes of flow from the fluid inlets to the mixing chamber. The first by-pass mechanism is responsive to the pressure of cold fluid flow in the manifold to allow cold fluid to flow between the cold fluid inlet and the fluid outlet. The second by-pass mechanism is associated with the temperature-responsive device and is responsive to a temperature in the manifold to allow cold fluid to flow between the cold fluid inlet and the fluid outlet.