Tankless Water Heater: The Step-by-Step Guide About How Does A Tankless Water Heater Work?

Water Heater

Last Updated on March 5, 2024 by Ali Hamza

Tankless water heaters operate differently from tanked water heaters, thus having distinct components. This is the case when the tap or shower is switched on. Therefore, instead of heating the water throughout the day and night, the tankless heater remains shut off until it is required. In this article, you will learn how a tankless water heater works.

Inside the tankless system, burning occurs when the system detects the need for hot water. If the hot water is turned out, it switches to standby. A tankless water heater includes a vent to expel any gas outside the house.

How does a tankless water heater work?

Tankless water heaters heat water immediately since they lack a storage tank. Cold water enters the appliance through a heat exchanger, which is heated by a natural gas burner or an electric element, when a hot water faucet is opened. Therefore, tankless water heaters deliver a constant flow of hot water. To make it easier for you to understand how a tankless heater functions, here are the steps to follow:

Step 1: The hot water tap is switched on

It is essential to ensure that hot water flows through your pipes. This involves switching off the hot water. If you only have one knob, make sure you switch it to your hot water. If you have two knobs, it’s a lot easier. Find the hot water knob and turn it through the boiling water.

Step 2: The water enters the heater

Now that you have hot water on, What should you be expecting? When you use a standard water heater, you expect hot water to flow from the tank to your pipes. But, with the tankless water heater, cold water flows through sensors, which trigger the internal computer, which will initiate the healing process.

Step 3: Flow sensors measure water flow

Once the internal computer is activated to calculate, it will immediately determine the temperature of the burners to bring the water up to the ideal temperature. This is done using a gas burner or an electronic element. Whatever method you choose will provide an ongoing hot water flow, and do not need to wait for the tank to refill.

Step 4: Using the computer, the burner will be ignited automatically

How does an in-tank water heater supply the hot water? When the burner can begin warming the water, it flows around an exchanger until it has reached its temperature. After that, the hot water is released from the tankless heater and flows through the pipes until it reaches its final destination.

Step 5: Water flows throughout the exchanger

With the tankless water heater, you have an endless flow of hot water that you can use. If the need for hot water is no longer there, the tankless water heater shuts itself down automatically and ceases to use energy. This means that you will save energy and enjoy continuous clean hot water.

How to maintain the smooth working of a tankless water heater?

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1. The panel can adjust the gas valve and the mixing valve, and water flow to reach the desired temperature.

Most tankless water heaters come with an open front panel that permits users to manage the settings. The board allows homeowners to modify the gas amount according to the amount they’d like to consume. For electric tankless heaters, panels can also regulate the amount of electric power. This helps homeowners better control their electricity, water, or gas expenses.

The panel for tankless water heaters offers a variety of settings that can be personalized for mixing rate and the quantity that water flows. If installing the tankless water heater, homeowners should talk to the plumber about their preferred settings and request them to set the water heater to suit. The homeowners should be cautious about drastically altering the grounds of their heater if they don’t know the exact reason for the change.

2. Common issues with tankless water heaters can be caused by blocks, overloads, and ignition problems.

Although they’re often acknowledged for their overall efficiency and typically require less maintenance than water heaters in storage tanks, tankless water heaters don’t come free of problems. If homeowners use boiling water systems simultaneously, it may cause the unit to overheat. The system will struggle to get hot water flowing and eventually shut down. But, this problem is usually avoided by pre-emptive or mindful techniques.

Tankless water heaters may be troublesome if their air supply is stopped. If this happens, the heater is experiencing difficulties venting, creating overflow. Finding and fixing the issue is essential since it’s a severe chance of igniting risk. Another problem encountered occurs when the tankless heater cannot light. This is when heaters that run on gas experience problems regarding their fuel supply. The homeowners should ensure that the water and gas valves aren’t fully open because that’s often the root cause of the issue.

2. Common issues with tankless water heaters can be caused by blocks, overloads, and ignition problems.

3. Regular maintenance helps keep the water flowing and eliminates the buildup of minerals.

One problem that the water heaters in storage tanks and tankless heaters have in common is the possibility of mineral accumulation. As time passes, minerals can accumulate inside the heater’s water. The temperature creates calcium and magnesium that cause a scaly buildup, affecting the water heater’s function. Owners of homes should monitor their water. This can be done by monitoring the water’s quality and replacing and checking the filter. If the filter isn’t maintained regularly, this can impact the device’s longevity.

Advantages of Tankless Water Heaters

  • Unlimited hot water: You’ll never run out of hot water with a tankless water heater. The unit heats water on demand, so you can take as many showers, run loads of dishes, and do as much laundry as you need without running out of hot water.
  • Space-saving: Tankless water heaters are much smaller and more compact than traditional tank-style heaters, making them a great option for small homes or apartments.
  • Energy efficiency: Tankless water heaters are more energy efficient than traditional tank heaters because they only heat water when needed. This can result in lower energy bills and a smaller carbon footprint.

Disadvantages of Tankless Water Heaters

  • Initial cost: Tankless water heaters are more expensive to purchase and install than traditional tank heaters.
  • Limited flow rate: Tankless water heaters have a limited flow rate, meaning they may not be able to supply hot water to multiple fixtures simultaneously.
  • Maintenance costs: Tankless water heaters require more maintenance and cleaning than traditional tank heaters, which can add to the cost of ownership.


If you decide whether you should switch to the tankless heater, you must understand how a tankless water heater works? Apart from knowing how it functions, it would help if you understood the advantages of using a tankless heater. Having a constant flow in hot water is only one advantage. But, many people also appreciate the financial savings when they use a tankless heater, as it consumes less energy than a tanked model.


Apart from this, if you are interested to know more about 5 Types of Water Leaks then visit our Home Improvement category.