Cold Water Inlet Pipe
The inlet pipe (usually copper) is connected to the main cold water supply pipe and provides water to the tank.
Cold Water Control Valve
The cold water control valve allows the incoming cold water to be turned on and off. The valve may be turned off when the water heater is not in use, in an emergency when the water heater leaks, or when the water heater is being replaced or breaks down.
Cold Water Dip Tube
To prevent the incoming cold water from cooling the hot water leaving the tank (at the top), the cold water is introduced at the bottom of the tank (which is also closer to the heat source). When the cold water inlet pipe is located at the top of the tank instead of at the bottom of the tank on the sidewall, a dip tube is used to direct the cold water to the bottom of the tank.
Hot Water Outlet Pipe
The outlet pipe is a short pipe that extends in the top of the tank. Since the water at the top of the tank is generally hotter than the bottom (heat rises), the hot water is always taken from the top. For safety and energy conservation water heaters are factory set to 120 degrees Fahrenheit.
Anti-Corrosions or Sacrificial Anode
A rod placed in glass-lined metal water heater tanks to help prevent the tank from rusting (oxidizing). The anode rod, usually made of magnesium, attracts the corrosion-causing oxygen in the water. The rod protects the tank from eroding and eventually wears away. The rod must be replaced to prevent corrosion from accelerating. Replace the anode every year or as necessary.
The drain valve at the bottom of the water heater allows the tank to be drained. Sludge or sediment from the water or the sacrificial anode will collect at the bottom of the tank over time. Excessive sludge/sediment may lower the water pressure or reduce the water heating efficiency. Recommended maintenance includes draining the sludge once a year.
Temperature Pressure Relief Valve
The temperature pressure relief (TPR) valve is a safety device that is designed to prevent overheating and over pressurization of the water in the tank and should be tested annually.
Temperature Pressure Relief Valve Discharge Tube
A tube or pipe that is attached to the TPR valve to direct superheated water down to the floor and away from anyone in the discharge are in order to prevent scalding or burning.