What is a tankless water heater? Advantages and its working

In this article we explain What is a tankless water heater? how they are originated, what are the advantages of using them over the olden tank based water heaters and know the principle and working of these tankless water heaters.

What is a tankless water heater? and its advantages

A tankless water heater, also known as a demand-type or on-demand water heater, is a highly efficient and space-saving alternative to traditional storage tank water heaters. Unlike traditional water heaters that continuously heat and store water in a tank, a tankless water heater only heats water when it is needed. This not only saves energy and reduces costs, but it also provides an endless supply of hot water.

popular tankless water heaters

In 1929, a milestone was reached in the world of water heating technology with the patenting of the first tankless water heater. Developed by Stiebel-Eltron, this innovative device was the first of its kind, utilizing a coil immersion model that had the capability to heat water when it was needed. This revolutionary invention marked the beginning of a new era in water heating, paving the way for more efficient and cost-effective solutions.

How does a tankless water heaters work:

When a hot water tap is turned on, cold water enters the tankless water heater through a inlet pipe. The water then passes through a heat exchanger, where it is heated by either a gas burner or an electric element. The hot water is then sent to the outlet tap, the inlet pipe keeps on supply the cold or normal water to the heat exchanger as long as the hot water tap is open giving continuous supply of hot water with constant temperature.

The key components of a tankless water heater are the heat exchanger, thermostat, and flow sensor, which work together to ensure an endless supply of hot water at the desired temperature.

gas and electric tankless water heater working diagrams

One of the key components of a tankless water heater is the heat exchanger. The heat exchanger is a series of coils or tubes that the water flows through to be heated. Gas-powered tankless water heaters use a burner to heat the heat exchanger, while electric tankless water heaters use an electric element. The heat exchanger is designed to be highly efficient, transferring as much heat as possible from the gas or electricity to the water.

Another important component of a tankless water heater is the thermostat. The thermostat is used to control the temperature of the hot water. When the hot water tap is turned on, the thermostat sends a signal to the burner or electric element to start heating the water. The thermostat also monitors the water temperature as it passes through the heat exchanger, and adjusts the burner or electric element as needed to maintain the desired temperature.

Some tankless water heaters also feature a flow sensor, which is used to detect the flow of water entering the tankless water heater. The flow sensor is connected to the thermostat, and sends a signal to the thermostat to start heating the water when the flow of water is detected. This ensures that the hot water is available as soon as the hot water tap is turned on.


Energy efficiency:

One of the major benefits of a tankless water heater is its energy efficiency. Traditional storage tank water heaters can lose up to 30% of their energy through standby heat loss, where the stored water in the tank loses heat to the surrounding air. A tankless water heater, on the other hand, only heats water when it is needed, eliminating standby heat loss and reducing energy consumption by up to 30%. This can result in significant savings on energy bills over time.

Endless Supply of hot water:

Another advantage of a tankless heater is its ability to provide an endless supply of hot water. Traditional storage tank water heaters have a limited supply of hot water, depending on the size of the tank. Once the hot water in the tank is used up, it takes time to fill the water into the tank and heat them, which cause a delay in the hot water availability. A tankless water heater, however, heats water on-demand, providing a continuous supply of hot water without any interruption.

Longer lifespan:

A tankless water heater also has a much longer lifespan compared to traditional water heaters. A traditional water heater typically lasts between 8-12 years, while a tankless water heater can last up to 20 years or more. This is due to the fact that a tankless water heater doesnt has a storage tank which can get scales and even corrode after longer periods of time, and also it has fewer moving parts. These makes them last longer without worring about repairing costs.

Space-saving design:

In terms of installation, tankless water heaters are more compact and take up less space than traditional water heaters. They can be mounted on a wall, saving floor space and making them ideal for homes and businesses with limited space.

Lower maintenance cost:

Tankless water heaters require less maintenance in general, and the maintenance cost is lower than traditional water heaters. In storage tank water heaters the first thing to clean is tank, as water stays in it continuosly scales are formed from mineral deposits which needs to be cleaned. Even in tankless models these scales are formed but in very less quantity.

Fuel choice:

These heaters come in both electric and gas-powered models, which gives consumers a choice to choose the cost efficient fuel source according to their location and pricing. As some areas has higher electricity prices compared to gas, they choose Gas heaters or some areas has limited supply of gas, they choose electric heaters.

Eco friendly:

These heaters are more environmentally friendly, as they use less energy and produce lower emissions.


  • The initial cost of purchase and installation is typically higher than traditional water heaters.
  • Also, tankless water heaters require regular maintenance and cleaning to ensure optimal performance.
  • Additionally, if the hot water demand is high, multiple tankless water heaters may be needed to meet the demand, which can add to the water heater cost.

Capacity of heating is calculated in GPM in Tankless water heaters. So, check and choose according to your need.

Frequently Asked Questions (FAQ):

In conclusion, If you’re looking for an efficient and cost-effective way to heat your water, a tankless water heater is definitely worth considering. However, they do come with a higher initial cost and require regular maintenance. It’s important to evaluate the specific needs of your household or business and weigh the costs and benefits before making a decision.

Joseph Miller

Joseph Miller is a highly experienced water heater repair expert with a passion for keeping homes warm and comfortable. With over 50 years of industry expertise, Joseph has developed a deep understanding of water heater systems and the intricacies of their repair and maintenance.

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  1. I find it fascinating that a tankless water heater helps you get an instantaneous source of warm water. My friend wants to help his aunt with her big move into the countryside this year. I should share this information with him so we can find a plumber that can install a water heater around her new home.

  2. Having a much lower maintenance cost is a really impressive fact for me as a homeowner. With appliances like these, we can lower the need for constant chores around here and reduce the stress we feel every day. Since hot showers are really important to us, I’ll get a plumber to help us install one of these models right away.

  3. It’s very interesting to know that a tankless water heater is able to save us energy. My wife and I moved to another house with an incredibly old and rusted water heater. We want to invest in a new one because we enjoy having warm water in the winter. We’ll keep your insight in mind when we check out water heaters soon.

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