An anode rod is a sacrificial metal rod installed inside a water heater tank. It attracts corrosive elements in the water, protecting the tank's inner lining from rust and corrosion. Over time, the anode rod corrodes and needs to be replaced. Regular inspection and replacement of the anode rod can significantly extend the life of your water heater. 

The cold water inlet valve is a component on your water heater that controls the flow of cold water into the tank. It's typically located on the cold water supply line. This valve ensures a steady supply of cold water for heating. 

A dip tube is a pipe inside a water heater tank that delivers cold water to the bottom of the tank. This design ensures that the cold water is heated efficiently as it rises to the top, where hot water is drawn off. 

A stainless steel drain pan that your water heater sits in to collect any potential leaks or drips. It's essential to regularly check the pan for water and address any issues promptly to prevent water damage. 

The expansion tank is that small tank on top of your water heater connected to the top plumbing. This helps to accommodate the expansion and contraction of water as it heats and cools. It also prevents excessive pressure buildup in the system, which can lead to leaks or damage.

The gas valve controls the flow of gas to the burner, regulating the water heating process. Gas valves are typically equipped with safety features to prevent gas leaks and accidental ignition. This is the number one thing that goes wrong on water heaters. A malfunctioning gas valve will cause inconsisent water temperatures due to the lack of fuel getting to the pilot assembly. 

An electric water heater uses one or two heating elements to heat the water. These elements are submerged in the water tank and convert electrical energy into heat. The thermostat controls the operation of the heating elements, turning them on and off to maintain the desired water temperature. 

A pilot light is a small, constantly burning flame used to ignite the main burner in natural gas and propane water heaters. It provides a continuous source of ignition, ensuring that the water heater can be lit quickly and efficiently. It is powered by the gas valve.

A recirculating system typically includes a pump, a timer, and additional piping to create a loop. When activated, the pump circulates hot water through the pipes, keeping it warm and ready for use instantly. These pumps are generally located at the top of your water heater attached to the top plumbing, but can also be found to the side or back of the site.

Supply lines are the pipes on top of your water heater to supply the cold water to the tank and pump hot water to the fixtures in your house. They are typically made of copper or flexible stainless steel corrugated hoses. 

A T&P relief valve is a crucial safety device installed on water heaters. It's designed to automatically release excess pressure and temperature to prevent the tank from exploding. This valve is typically located near the top of the water heater. It's important to have the T&P valve inspected and replaced periodically to ensure its proper functioning as it is the main safety valve on your water heater.

A water heater's temperature control, often a dial on the gas valve, allows you to adjust the desired water temperature. This setting determines how hot the water will be when it reaches your faucets. It's important to set the temperature to a level that balances energy efficiency and safety. 

A heat exchanger which transfers heat from a heat source, such as a gas burner or electric element, to the water being heated. The number two issue with water not getting as hot as it should is the thermal pile going bad.