An object of the invention is to provide a hot and cold water mixing device for reducing degradation in the measurement accuracy of a flowmeter. In the device according to the invention, the flowmeter is disposed in one of a hot water supply path and a cold water supply path, having a higher flow rate. At least first and second temperature sensors are individually disposed in at least two of the hot and cold water supply paths and a mixed water path. A hot and cold water adjustment unit adjusts a mixing volume of hot water and cold water based on measurement values of the flowmeter disposed in one of the flow paths having a higher flow rate, a mixed water path flowmeter and at least the first and second temperature sensors.

A water heater appliance includes a tank and a heated water conduit extending from the tank. A mixing valve is coupled to the heated water conduit, and a heat trap is mounted to the heated water conduit upstream of the mixing valve. The heat trap includes a membrane disposed within the heated water conduit. The membrane of the heat trap may assist with obstructing recirculation of heated water from the tank into the heated water conduit.

The valve includes a housing, a thermostatic element, a first shutter displaced by the thermostatic element along an axis relative to a first seat integrated into the housing to control a flow of fluid between the first and second paths, a cage, a first return spring, a second shutter axially displaced by the thermostatic element relative to a second shutter axially displaced by the thermostatic element with respect to a second seat integrated into the cage, a third shutter axially displaced by the fluid overpressure in the second path relative to a third seat integral with the cage, and a second return spring. The cage includes a tubular part, which is centred on the axis and through the interior of which fluid flows between the second and third paths. An outer face of the tubular part is provided with a seal. The cage also includes arms.

A method of controlling mixed liquid to be delivered for SPM solution includes: before the SPM solution comes into an acid scouring tank, mixing the sulfuric acid with the hydrogen peroxide in a delivering pipe in a first stage and a second stage in turn, so as to make a mixed liquid after mixing in the first stage to further get mixed in the second stage; heating the mixed liquid in the first stage; monitoring an oxygen concentration value of the mixed liquid flowing out after mixing in the first stage; and if the oxygen concentration value is smaller than an oxygen concentration value at full reaction, adding supplementary sulfuric acid and hydrogen peroxide during mixing in the second stage, so as to enable the oxygen concentration value of the mixed liquid flowing out after mixing in the second stage monitored in real time to reach an oxygen concentration value.

A method of controlling mixed liquid to be delivered for SPM solution includes: before the SPM solution comes into an acid scouring tank, mixing the sulfuric acid with the hydrogen peroxide in a delivering pipe in a first stage and a second stage in turn, so as to make a mixed liquid after mixing in the first stage to further get mixed in the second stage; heating the mixed liquid in the first stage; monitoring an oxygen concentration value of the mixed liquid flowing out after mixing in the first stage; and if the oxygen concentration value is smaller than an oxygen concentration value at full reaction, adding supplementary sulfuric acid and hydrogen peroxide during mixing in the second stage, so as to enable the oxygen concentration value of the mixed liquid flowing out after mixing in the second stage monitored in real time to reach an oxygen concentration value.