What are the most common water heater parts that need replacing?

Whether you have a gas water heater or an electric model, you’ll find that some parts eventually wear out and need replacement. Electric and gas water heaters also have some common parts unique to their type that need replacing.

Common replacement parts for gas and electric water heaters

Anode rod

The anode rod extends into the tank from the top panel of the water heater. Made of aluminum or zinc, the anode rod helps prevent tank corrosion by aggressively attracting oxidizing compounds that would normally corrode the tank. The tank lasts longer because the anode rod corrodes instead of the tank.

You may need to replace the anode rod when your hot water smells like rotten eggs. Certain water conditions cause a reaction between a water heater's anode rod and supply water, causing hydrogen sulfide gas to dissolve in the tank water. The hydrogen sulfide gas gives the water a rotten-egg smell. Installing a less-reactive aluminum alloy anode rod and chlorinating the water supply system eliminates the rotten-egg smell in hot water.

Dip tube

The dip tube is a high-temperature plastic tube that is inserted into the tank through the cold-water inlet port. The dip tube extends far down into the tank to distribute incoming cold water at the bottom of the tank for efficient heating.

Drain pan

The drain pan sits under the water heater and catches water if the tank cracks or leaks water. Catching the leaking water in the drain pan prevents damage to walls and the floor surrounding the water heater.

Drain valve

The drain valve fits at the bottom of the tank and allows you to drain water from the tank. Replace the drain valve if it leaks or won’t open.

Expansion tank

The expansion tank is a small water tank installed in the water supply line to the water heater. The expansion tank contains an air bladder that partially fills the tank. The air bladder cushions water hammer and absorbs excessive water pressure caused by thermal expansion. Water hammer is a pressure surge caused when water flow is forced to stop or change direction suddenly, which results in a hammering sound. Thermal expansion is a change in volume in response to a change in temperature through heat transfer.

Heat trap

The heat trap is a one-way check valve nipple that attaches to the cold-water inlet and hot-water outlet on the tank. The heat trap prevents heat loss from convection and thermal siphoning of hot water.

Temperature-pressure relief valve (T&P valve)

The temperature-pressure relief valve (T&P) is a safety device attached to the side of the tank. If a thermostat fails, water inside the tank overheats and builds up pressure that can damage the tank and tank fittings. The T&P valve opens automatically and discharges water to relieve pressure if excessive pressure builds up in the tank.

What are the most common electric water heater parts that need replacing?

In addition to the above parts common to both gas and electric water heaters, certain parts that are unique to electric water heaters often need replacement.

Here’s a list of the top electric water heater replacement parts:

Heating element

The heating element, which is the heat source inside an electric water heater, extends directly into the tank, where it heats the water around it. Most electric water heaters have two heating elements, one at the bottom of the tank and one at the top. The bottom element handles most of the load, heating cold water as it enters at the bottom of the tank. The top element only operates to give water at the top of the tank a quick water-heating boost when needed.

Thermostat

The thermostat monitors water temperature in the tank. When water temperature drops beneath the desired setting, the thermostat turns on the electric heating element. When the water temperature in the tank reaches the set temperature, the thermostat shuts off the element.

Before you replace electric water heater parts, you’ll want to diagnose the cause of the water heating failure.

Watch this troubleshooting video to help you determine the cause of an electric water heating failure: