An Overview of How a Hot Water Heater Works

If you’ve ever wondered how your how water tank or tankless water heater works, this article is for you.

A hot water heater is a staple in every home. Without it, you would not be able to enjoy hot water when washing, showering, doing dishes, and so on.

There are two main types of hot water heaters available: traditional hot water tanks, and modern tankless water heaters. Both types accomplish the same objective: to provide you with a reliable supply of hot water.

In this article we are going to break down the differences between the two types of water heaters as well as provide a summary of how each type of water heater functions.

In The Tri-State Area, You’ll Likely Find One of Two Types of Water Heaters in Your Home

Chances are that your home has a hot water tank in the utility room. This type of hot water has been used for decades and is a familiar sight in most homes.

Tankless hot water heaters are relatively new, becoming increasingly popular over the last several years. Tankless water heaters are smaller, generally more efficient, and can provide an endless supply of hot water.

Most Common: The Classic Hot Water Tank

A water heater that has an integrated storage tank is often referred to as simply the “hot water tank”. You can find these in various sizes, though 40 gallon tanks are the most popular.

A hot water tank uses either a gas or electric heating element to heat and store water at a set temperature. Most homes in the tri-state area use natural gas as the fuel for their hot water heater, though electric and propane units are fairly common as well.

Gaining Ground: Tankless Water Heaters

This type of water heater does not require a large storage tank, making them considerably smaller than a hot water tank. As a result, a tankless water heater has more options in terms of where it can be installed (as it does not require significant floor or wall space).

A tankless water heater heats water as it passes through it, only heating hot water that you will actually use.

Technology and affordability for tankless water heaters have really improved in recent years, fuelling their increasing popularity.

Here’s a High Level on How a Hot Water Tank Works

A tank-style water heater has four main mechanisms at work: the gas burner/electric heating element, the storage tank, an anode rod, and built-in safety features. These four systems work seamlessly with each other and ensure the safe and reliable operation of the water heater.

Important Components

  • The heating element – Most hot water tanks have a natural gas or propane-fuelled heating element, though some have an electric heating element instead. Regardless of the type of heating element used, it performs the same function: the element heats the water stored in the water tank to a specified temperature, ensuring that it is available “on demand”.
  • Hot water storage – Most water heaters are connected to a 40 gallon storage tank, though you can commonly find water heaters with larger and smaller storage tanks.
  • Anode rod – The anode rod sits inside of the hot water tank and is designed to corrode. By facilitating corrosion on the anode rode, the tank itself is spared. This extends the useful life of the water heater.
  • Safety mechanisms – All hot water heaters are equipped with several built-in safety mechanisms. Since the water in the hot water tank is heated and stored, it is kept at a certain level of pressure. The safety mechanisms are designed to engage in the event that the temperature or pressure of the hot water heater exceed predefined limits. Most water heaters have multiple layers of safety devices.

When you turn the tap to “hot”, the water heater sends heated water through your pipes as needed. Once you use the hot water that has been stored you will run out (as many people have found out halfway through their morning shower). Once you exhaust your supply of hot water, you will not have hot water again until your water heater has been able to heat the water stored in its tank.

The Differences Between Natural Gas/Propane & Electric Water Heaters

Aside from a difference in fuel, the most tangible difference between a gas and electric water heater is the inclusion of a second thermostat on most electric models.

A gas water heater uses a burner at the base of the water heater to bring the water to temperature. In an electric model, heating elements are used – typically in pairs – to heat the water.

Some notable points:

  • Electric water heaters are approximately 30-50% more efficient than natural gas or propane water heaters.
  • Life spans for both types of water heaters range from 12-15 years.
  • A natural gas or propane water heater will usually outperform an electric water heater in terms of heating rate. Gas water heaters generally bring water to temperature faster.

How Tankless Water Heaters Work

Tankless water heaters utilize a heat exchanger to heat hot water as it flows through the water heater. Because a tankless water heater does not store its supply of hot water, there is no cost associated with maintaining a large tank of stored hot water.

When hot water is requested the tankless water heater activates (either the burner engages or an electric heating element turns on), heating water as it travels through the heat exchanger.

Many tankless water heaters boast being able to provide a “limitless” supply of hot water. However, independent tests have demonstrated that excessive demand will tax most tankless water heaters as it would a traditional tank-style water heater.

Tank or Tankless: Which Type of Water Heater is Best For You?

Many people in the Tri-State area find themselves needing to replace their water heaters. Suburbs that went up in the mid-late ‘90s are likely looking for water heater replacements right around now.

There’s an ongoing debate regarding the choice of a hot water tank or itsm tankless equivalent. For a family of 3, a single 40 gallon water tank is likely sufficient for their needs. This option will be affordable and reliable for most people. A family of four of five may want to consider adding a second water tank, or moving to a tankless water heater that can output more hot water than a single 40 gallon tank can.


  • In most cases, the long-term cost of a tankless gas-powered water heater is the lowest
  • Electric water heaters tend to have a higher upfront cost than gas water heaters
  • If you are considering switching from an electric water heater to a gas one, you must also consider the cost to add a gas line to the utility room


  • Hot water tanks store a sizable amount of water that they can release on demand. However, once expended, these tanks require a recovery period to reheat their stored water.
  • Tankless water heaters are often capable of long-periods of sustained hot water and are ideal for larger families, where hot water may occasionally run out.
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