The faucets that bring water to the shower can be divided into two categories: 1) Pressure Balance Valve system, or 2) Thermostatic Valve system. Pressure Balance Valve systems are typically used in a bathtub/shower combination where a diverter is used to divert the water flow to either the tub spout or to the shower head. Pressure balance valves can also be used in separate shower fixtures where the only water outlet is the shower head, or sometimes, although not always recommended, to divert the water from the shower head to a handheld shower. Pressure Balance Valves detect a change in the amount of hot or cold water supply, for example when a toilet is flushed, it will detect the lower cold water pressure and will adjust the amount of hot water flow to balance out the lack of cold. A pressure balance system is, however, limited to only two water outlets, and also will only allow water flow to one outlet at a time, not both at once, which if desired, then a Thermostatic Valve Shower system is required. Thermostatic Valve shower systems offer more diverse shower experiences on two main levels: 1) you can have three or more shower outlets running simultaneously or in any combination; and 2) you can set the exact water temperature you wish to shower in. A thermostatic system consists of: A) the thermostatic valve which works only to maintain the water temperature at the desired setting; and B) several volume controls which turn the water on or off for each shower outlet. Thermostatic shower systems are used when there are three or more water outlets desired, such as adding body jets to your shower, and when a consistent preset water temperature is desired, as well as when water flow is desired simultaneously from any combination of shower outlets. Before investing in a thermostatic shower system, it is advisable to check your home�s water pressure first, because each outlet, to function properly, requires water flow of approximately 2.9 gallons per minute. Therefore, If you wish to have running simultaneously a shower head, a hand held shower, and two body jets, you will need water pressure of approximately 12 gallons per minute for the entire system to function effectively. We welcome you to come in and see us for more information on achieving your optimum bathroom shower.