Features

• A three-handle shower and tub system has two handles that control hot and cold water flow and a center handle that controls the shower diverter valve. A two-handle system has a lever on the tub spout that engages the shower diverter valve. The tube-shaped shower diverter valve sits behind the diverter knob or lever in a combination shower and bathtub. The Home Tips website notes that although a pressure balance valve outwardly resembles other bathtub valves, it has an added piston or diaphragm that senses water pressure changes.
  
  

Function

• A shower diverter valve directs water through either the tub spout or the shower head. In a typical two-valve diverter system, the hot and cold taps first send water through the tub faucet. After the water reaches the desired temperature, a turn of the diverter knob or lever blocks water from the tub spout and sends it through the shower head. A pressure balance valve prevents dramatic temperature changes by sensing pressure fluctuations in water pipes. When the piston or diaphragm senses changes in hot or cold water flow, the balance valve adjusts the water flow to prevent temperature changes greater than 3 degrees F.
  
  

Benefits

• Building codes require pressure balance valves or other anti-scald devices for shower fixtures. The pressure balance valve helps prevent burns or scalding as it minimizes changes in water temperature. A diverter valve allows the bather to test the water temperature at the tub spout before the water sprays from the shower head. A properly functioning diverter valve prevents water waste as it blocks water from entering the tub spout while the shower is in use.
  
  

Considerations

• After years of use, a worn diverter valve can cause waste when it allows water to flow simultaneously through the shower head and the tub faucet. Shower water temperatures can suddenly increase or decrease if the pressure balance valve is worn-out or broken. According to PlumbingProfessional.net, clogged or aging pipes can cause an uneven flow of hot or cold water. A professional plumber can replace a worn-out or malfunctioning pressure balance or diverter valve.