Figure 5-27.Bathtub and shower piping arrangement.
sudden changes of temperatures due to slugs of hot or
cold water from varying pressures or water
temperatures in the supply lines.
The pressure-controlled mixing valve, like the one
shown in view A, figure 5-28, consists of a brass
mixing chamber that contains a sliding piston. The
piston has jets to allow hot and cold water to pass
through them and mix when the handle of the valve is
operated. The setting of the handle controls the water
temperature by establishing the mixing ratio. A change
in pressure on one side of the piston causes the piston to
move and increases the flow from the low-pressure
supply to maintain a nearly constant pressure.
The thermostatically controlled mixing valve,
similar to the one shown in view B, figure 5-28, is
sensitive to changes in both temperature and pressure.
The temperature of the water delivered by the valve
remains constant regardless of the temperature and
pressure changes in the hot and cold waterlines. The
thermostatic mixing valve is used for showers only.
The shower head is attached to a 45-degree fitting
mounted on a chrome pipe. There are two general types
of shower heads: circular and economy. The circular
spray head shown in figure 5-29 has notches or
Figure 5-29.Types of shower heads.
Figure 5-28.Shower mixing valves.