Inside a Water Heater
Let's take a quick look at the components that work together in your water heater to make your morning shower so satisfying:
- Tank - The inner shell of a water heater is a heavy metal tank containing a water protective liner that holds 40 to 60 gallons (151 to 227 liters) of hot water at around 50 to 100 pounds per square inch (PSI), within the pressure range of a typical residential water system. The exterior of the tank is covered in an insulating material like polyurethane foam. Over that, there's a decorative outer shell and possibly an additional insulating blanket [source: APEC].
- Dip tube - Water enters the water heater through the dip tube at the top of the tank and travels to the tank bottom where it's then heated.
- Shut-off valve -The shut-off valve stops water flow into the water heater. It's a separate component from the heater located outside and above the unit.
- Heat-out pipe -Suspended toward the top of the tank's interior, the heat-out pipe allows the hot water to exit the water heater.
- Thermostat - This is a thermometer- and temperature-control device. Some electric water heaters have a separate thermostat for each element.
- Heating mechanism - Electric water heaters have heating elements inside the tank to heat the water. Gas water heaters use a burner and chimney system instead.
- Drain valve - Located near the bottom of the exterior housing, the drain valve makes it easy to empty the tank to replace the elements, remove sediment or move the tank to another location.
- Pressure relief valve - This safety device keeps the pressure inside the water heater within safe limits.
- Sacrificial anode rod - Made of magnesium or aluminum with a steel core, the sacrificial anode rod is suspended in the water heater tank to help retard corrosion.
Now, let's see how all these parts work together to provide you with hot water.