A Needle  Valve is  sometimes used in equipment that controls the temperature of water within a specific system. For example, some residential water heaters utilize this type of valve as a type of bleed valve that makes it possible to relieve pressure on the water flowing through the device. As with other applications, the valve makes it possible to control the flow of water through the heater, a factor that can also aid in minimizing the amount of energy needed to maintain an equitable supply of hot water.

Reference

Instrument Manifolds

Cast Steel Valves

Forged Steel Valves

Hydraulic control valves

Water Control valves