How Does Tankless Water Heater Work?

A Tankless Water Heater means that there is no tank to store hot water. These types of water heaters are in huge demand nowadays due to less space requirement and more energy efficiency.

In India, we call tankless water heater Instant Water Heater which are available in the range of 3-5 liters capacity.

You might be wondering why I am mentioning the capacity when there is no tank at all. We will find the answer to this question and numerous other queries here in this article.

What Is Tankless Water Heater?

In a tankless water heater, there is no water tank. The water gets heated when water passes through the heat exchanger in the water heater. That is why it is called an on-demand water heater as you will get hot water when it is required.

Tankless Water Heater

It is also called Instant Water Heater as you will get hot water almost instantly. Traditional storage water heaters take around 10 minutes to give hot water. Instant water heater does not have any space to store hot water.

Tankless water heaters are energy efficient, consume less space, and provide instant water. That is why these are preferred among consumers.

How Does Tankless Water Heater Work?

When there is a demand for hot water, water passes through the heat exchanger of the water heater and gets heated. The heater unit sensor will only activate when it senses the flow of water.

How Does Tankless Water Heater Work?

How much water your water heater can heat depends on the flow rate. For example, when we talk about a 3-liter instant water heater, it means that it can heat up to 3 liters of water per minute. It does not have anything to do with storing water.

Tankless water heaters are powered by either electricity or gas. Gas is preferred if you want to use multiple outlets for hot water. However, the initial investment is more for gas water heaters.

Benefits Of Tankless Water Heater

There are a bunch of benefits that tankless water heaters offer as shown below.

Energy Efficient

You get hot water when you need it. It does not heat up and store hot water. So there is no wastage of water and the power consumption is also optimum.

There are no standby energy losses associated with keeping a large tank of water hot all the time.

Occupy Less Space

Tankless water heaters are typically smaller in size as there is no water storage tank. So if you are running short of space, tankless water heaters are the best option as these occupy less space.

Instant Hot Water

You will get hot water almost instantly whereas storage water heaters takes about 10 minutes to give hot water. How much hot water per minutes tankless water heaters can supply depends of the flow rate of the unit. More the flow rate, more the amount of hot water per minutes.

Powerful Heating Element

Since tankless water heaters offer instant hot water, they uses high power heating element typically in the range of 3000-4000W. Traditional water heaters uses 2000W heating element.

Please remember that high-power heating elements consume more electricity too. That is why tankless water heaters are good for day-to-day chores like washing dishes, hand washing, or tanking baths using buckets.


Installation is easy as tankless water heaters are small in size and can be tucked anywhere. If you opt for gas-powered tankless water heaters, then you may need to call a trained technician to do the job for you.


All water heaters require regular maintenance. However, you may not need to service tankless water heaters as frequently as storage water heaters.

Since there is no tank, scaling formation is limited, and so are the other issues. Heating coil burnout could be more frequent in tankless water heaters. Overall, tankless water heaters are a good choice in terms of maintenance.

Cons of Tankless Water Heaters

The limited flow rate could be a concern for many. If you want to use multiple faucet at the same time, you may end up getting cold water in many outlets as the flow rate is limited.

You may opt for a high-flow rate tankless water heater, but that will cost you almost the same as a storage water heater.

The initial set up cost is also a concern especially if you plan to use gas to power your water heater.

Conclusion: Tankless Water Heater

Tankless water heaters are a great choice if your usage are not that high. These are energy efficient, provides instant water and can be installed anywhere.

Sometimes these benefits can be outperformed by storage water heaters if the individual requirements do not comply with having a tankless water heater.

Rajib Is The Founder And The Key Brain Behind RiansDeal. A NIT 2004 Graduate In Mechanical Engineering With Close To Two Decades Of Experience In Designing Large Appliances And Consumer Electronics Products.


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