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How Does a Hot Water Heater Work?

Hot water Heater Tank

What is a Hot Water Heater?

A hot water heater is an appliance that heats water to a temperature between 120 and 130 degrees Fahrenheit. It can be gas or electric and used to provide hot water for your home.

A water heater provides a steady stream of hot water to the various fixtures throughout the building and is one of the most important appliances in any home or residential building. Although the basic design of water heaters is simple, there are many different variants available.

How Does a Hot Water Heater Work?

The process begins when you turn on the hot water faucet in your bathroom or kitchen. The cold water enters the tank through an inlet valve, which is opened by a float valve that senses when the tank is full. The cold water passes through a heat exchanger, where it picks up heat from the combustion process (in an electric model) or from burning natural gas (in a gas model). When the water reaches about 120 degrees Fahrenheit (49 degrees Celsius), it flows into your pipes for use around your house–but not before passing through another set of valves that let you control how much hot water comes out at once.

Components of a Hot Water Heater

Now we’ll look at the different parts that work together to produce the hot water you need. Similar parts are found in both electric and gas water heaters, but there are some differences between the two. This will help you understand how a hot water heater works.


The majority of water heaters found in homes throughout the United States have large, insulated tanks that store your hot water. These water heater tanks are available in a variety of sizes, holding anywhere from 20 to 80 gallons. The size of the hot water tank should be proportional to the number of people in the home needing hot water, and a typical household tank has a 40-60 gallon capacity.

Dip Tube 

The dip tube carries cold water from your home’s municipal supply, well, or another water source into the tank. Your main water line has a split right before the water heater. When you turn on the cold water tap, the water is piped from the main valve through the cold water service line. 

Water that comes through the hot water tap goes into the tank through the dip tube. This is before the water travels through the hot water service line. The dip tube is located at the top of the tank. The cold water enters here and then heats from the bottom of the tank.

Heating Element / Gas Burner

Electric water heaters use an electric heating element to heat the water within the tank. Gas-powered water heaters use gas burners to heat up the water. Both are located at the bottom of the tank.

Anode Rod 

The anode rod is another safety measure. It prevents the tank from rusting through electrolysis. This means that the metal-coated steel rod (generally coated in aluminum, zinc, or magnesium) rusts instead of the steel lining of the tank’s interior.


Water heaters have a thermostat on the outside that allows you to monitor and control the temperature of the water.

Heat-Out Pipe 

The hot water service line connects to the water heater, which pumps hot water from the tank. It’s located at the top. As hot water has less density than cold water (and heat rises by nature), the hottest water rises to the top of the tank.


  • Drain Valve

The drain valve is located at the bottom of the tank, outside of its enclosure. As its name suggests, the drain valve is used to drain out sediment that builds up inside the tank. 

  • Shut-off Valve

A shut-off valve is located outside of the water heater. This valve shuts off the flow of water into the tank.

  • Pressure Relief Valve

The water inside the tank is under extreme pressure. The pressure relief valve helps to prevent potentially dangerous pressure buildups.

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The Five Main Types of Water Heaters

Each type of water heater has its own unique set of benefits and drawbacks, though they all perform the same function. Understanding the differences between the five main types of water heaters can help you choose the best water heater for your home or business.

  • Tankless Water Heaters

Tankless water heaters are engineered to heat water as soon as you demand it, which means that you can use an unlimited amount of hot water. Moreover, since they only heat water when you need it rather than constantly heating it in a large tank, tankless water heaters tend to be more energy efficient and thus cheaper to operate.

  • Storage Water Heaters

Storage-type water heaters are the most popular type of hot water heater. They heat water and then store it in a large tank. Storage water heaters can be either electric-powered or gas-powered, with gas models providing faster heating and electric models tending to be less expensive.

  • Heat Pump Water Heaters

Heat pump water heaters use the temperature of the air outside your home to heat the water inside the storage tank, rather than using an electric heating element. This means that you can save money on your energy bill, as the system requires little electricity to operate.

  • Condensing Water Heaters

Condensing water heaters can only be installed in homes that have a natural gas heating unit. They have a hot water storage tank that is powered by the exhaust gas from your central heating unit, rather than having a direct gas line as with traditional water heaters.

  • Solar Water Heaters

Solar water heaters use solar panels to collect energy from the sun and heat water. Solar water heaters provide hot water throughout the year, making them a more economical option than traditional electric or gas water heaters.

However, solar water heaters have one significant drawback: they only function when the sun is out. If you live in an area with excessive cloud cover, you may be forced to take cold showers for days at a time.


Hot water is important to your health, as well as your comfort. It allows you to wash away the day’s dirt and grime, and it keeps your skin looking youthful and healthy. Hot water also helps you relax after a long day at work or school so that you can unwind before heading off to bed.

It isn’t just for cleaning–it can also be used for cooking, which means that you won’t have to heat up an entire pot of water just for one dish!

Once you understand the principles of a hot water heater, it’s not hard to figure out. When you have an issue with your hot water heater, need some preventative or general maintenance? Or draining your hot water heater sediment? There’s no one more reliable than our team of professionals!

If you’re in Minnesota, contact our team to avail the highest quality home maintenance for your property! Dial (612) 503-4050 now or email us.

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