Overview of Water Heater Components

Here's a blueprint to all the hidden parts of your water heater

Grandpa and grandson adjusting water heater temperature
Photo: Westend61 / Westend61 / Getty Images
Grandpa and grandson adjusting water heater temperature
Photo: Westend61 / Westend61 / Getty Images
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Have you ever wondered what makes your water heater tick? While a household's hot water heater springs into action every time we clean or cook with hot water, the components of this essential home system remain a mystery to most people. A water heater's universal design consists of a large tank with supporting components, so you'll generally find the same basic blueprint for parts regardless of whether you have an electric or gas unit.

This guide to water heater components will leave you equipped to make sure your water heater keeps running smoothly.

What Are the Different Parts of a Hot Water Heater?

A hot water heater blueprint consists of an intricate series of components with unique tasks. After looking at these parts, it will be clear to see why keeping a water heater properly maintained is so important. Here's a look at universal hot water heater components that you'll find in both electric and gas water heaters.

1. Cold Water Inlet

The cold water inlet, located at the bottom of the water heater, opens to allow cold water to enter the unit's tank. Once in the tank, the water is heated by the unit's heating element or burner before being distributed to various plumbing fixtures throughout the home using available hot water lines.

2. Hot Water Outlet

Man installing hot and cold-water pipes on a water heater
Photo: Banepx / iStock / Getty Images Plus / Getty Images

Typically located at the top of a water heater tank, the hot water outlet is essentially the inverse feature of the cold water inlet. The outlet marks the spot where water that has been heated after entering through the inlet leaves the unit to be available at plumbing fixtures throughout a household.

3. Dip Tube

While this is one of the most inconspicuous water heater parts, the dip tube is essential for ensuring that hot water is consistently available in a home. This feature transports cold water to a burner located near the tank's bottom. After cold water is guided to the right spot, it's heated before being blended with existing reserves of hot water.

4. Temperature and Pressure Relief Valve

Water heater temperature and pressure relief valve
Photo: The Toidi / Adobe Stock

Also known as the T&P valve, this feature is crucial for safety and performance. The T&P valve will automatically engage in two scenarios. The first is if the temperature inside the tank reaches above 210 degrees Fahrenheit. The second is if the pressure inside the tank exceeds 150 pounds per square inch (PSI). In this event, the valve will open in order to allow pressure to escape from the tank. The highly important T&P valve is located on the top of the unit's overflow pipe.

5. Overflow Pipe

Also known as the discharge pipe, the overflow pipe is a component made of code-compliant plumbing material that descends from the aforementioned T&P relief valve. Its purpose is to provide an outlet for excess pressure and moisture to escape if pressure and temperature conditions within the tank become elevated. The state of an overflow pipe can provide a critical red flag! If you notice water leaking from the overflow pipe, this is a sign that the water heater's pressure and temperature are well above safe levels.

6. Drain Valve

Hose connected to water heater drain valve
Photo: NC Photo / Adobe Stock

Equipped with two openings, the drain valve is designed to allow for a water heater to be easily drained for maintenance, repairs, or replacements. It is commonly used when flushing debris and sediment from a tank. The valve's threaded ends allow for an easy connection to a hose.

7. Sacrificial Anode Rod

Old and new sacrificial anode rods on a gray surface
Photo: Aleksandr Uglov / Adobe Stock

The role of the anode rod is to disintegrate over time. It gets its name as the "sacrificial" rod because it absorbs corrosive minerals and materials instead of allowing them to destroy the tank. Anode rods used in water heaters are made of zinc, aluminum, or magnesium. Depending on usage, anode rods need to be replaced every three to five years.

Parts That Are Exclusive to Electric Water Heaters

6 electric water heater parts illustrated, including the cold water inlet, hot water outlet, and drain valve

When comparing different types of water heaters, homeowners are likely to notice that electric versions contain fewer parts compared to gas versions. That's because electric water heaters have simpler heating systems. Here's a look at the parts of an electric water heater.

1. Heating Element

A standard electric water heater will have two metal rods that serve as the unit's heating elements. While the element located at the bottom of the unit heats up water, the secondary element on the top portion of the tank can help to retain water temperature when the household demand is higher.

2. Power Supply

For safety purposes, an electric water heater requires its own dedicated power outlet. The standard circuit requirement for an electric heater is 240 volts. Additionally, an appropriately sized breaker is needed to prevent overheating.

3. Thermostat

Electric heaters have special thermostats that continuously monitor temperature. Both heating elements within an electric heater will have dedicated thermostats.

Parts That Are Exclusive to Gas Water Heaters

7 electric water heater parts illustrated, including the cold water inlet, hot water outlet, and draft hood

Many homeowners prefer gas water heaters due to their quick heating performance and low cost of operation. Unlike electric heaters, which require little more than a dedicated outlet to operate, gas heaters need proper venting when they are installed. Here's a snapshot of a gas water heater diagram.

1. Gas Burner

While an electric water heater has dual heating elements, a gas water heater relies on a gas burner as its heat source. The burner is found at the bottom of the water heater near a pilot component called the thermocouple. The thermocouple automatically opens and closes the gas valve.

2. Pilot Assembly

A water heater's pilot assembly is what ignites the gas burner. Most people are familiar with open-flame pilot ignition, which has been standard for years. However, this is just one potential option that might be on your unit. The other option is a spark ignition pilot that needs to be connected to a power source to work.

3. Gas Valve

The gas valve controls the gas supply that enters the water heater. It is located on the external lower portion of the unit. While this valve controls access to the gas supply, it does not control the water supply.

4. Flue Baffle

A water heater's flue baffle helps to direct toxic fumes out of the unit. After trapping gases, it directs them upward to vent out from the unit via the draft hood. This component is generally made of metal.

5. Draft Hood

A draft hood is a circular metal piece that's roughly 3 feet in length. Its purpose is to help funnel flue gasses away from the main unit in conjunction with the flue baffle. Once fumes reach the draft hood, they are carried out via the vent run.

6. Blower

The blower on a gas water heater helps to push fumes outside. As it redirects fumes, it also helps to cool them down. As a fan, a blower actually requires a dedicated power source that is separate from the water heater.

How to Maintain the Different Parts of a Hot Water Heater

Giving your hot water heater a robust visual inspection every few weeks to spot leaks or burst pipes can help you catch a major mechanical or plumbing issue. It's also helpful to simply glance at the unit every time you pass by it to look for signs of trouble. One wise homeowner tip is to arrange to have your water heater inspected by a pro whenever you schedule annual furnace maintenance at your home.

The most important bit of maintenance you can perform to keep hot water heater components running smoothly is flushing. Ideally, you should flush your water heater at least once every 12 months. In most homes, flushing twice a year is necessary due to hard water or excessive sediment. If you're uncomfortable flushing your own water heater, getting an estimate for local water heater flush cost can help you to get the task done.

Cost to DIY Hot Water Part Repair vs. Hiring a Pro

On average, the cost to repair a hot water heater is $600. However, repair costs can range anywhere from $90 to $1,725 based on the complexity of the issue. When merely replacing a water heater component on your own, prices can range from as low as $25 for a new anode rod to more than $400 for a new thermostat. However, homeowners who attempt a DIY hot water part repair on their own run the risk of causing damage to the unit which could result in the need for a full water heater replacement cost that falls between $880 and $1,800. Improper repairs or part replacements could also result in leaks, fires, and other dangerous scenarios.

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