Go Back

How Does a Tankless Water Heater Work?

tankless water heater

Tankless water heaters offer a space-saving option to provide hot water to your home. As the name implies, they do not require a tank which often has homeowners scratching their heads when trying to understand how they work. Here we explain how a tankless water heater works and why a tankless water heater might be right for you.

What is a Tankless Water Heater?

Tankless water heaters do not have a storage unit for water. Instead, they heat water as it is required. Hot water is available “on-demand” using a heating system that heats the water when a hot water tap is turned on.

What are the Benefits of a Tankless Water Heater?

Tankless water heaters can save energy because you don’t use energy to heat a tank 24/7. As a result, you can help reduce your energy bills each month. They also free up more space which can work well for smaller homes. You also have an endless supply of hot water, so there’s no risk of an unpleasant cold shower if you’re the last to use the bathroom each morning.

Because there is no tank, you can’t “run out” of hot water. They are also eco-friendly, not just for their low energy consumption, but also because the tankless system only requires repairs, or small parts replacement, unlike a massive tank. This means less waste ends up in the local landfill site. As well, tankless water heaters last up to 20 years or more with proper maintenance. That’s up to three times longer than hot water tanks.

If There’s No Tank, What Makes Up a Tankless Water Heater?

Tankless systems are basically like small heaters that hang on the wall. They comprise a burner to heat the water and parts that direct the water through the system and into the pipes. They work using flow sensors that read signals to trigger the system when hot water is turned on anywhere in the house. The heater automatically turns off when the hot water tap is turned off.

How Does a Tankless Water Heater Work?

Tankless water heaters trigger seven steps when the hot water tap is turned on:

1. Flow Sensors Detect Water

When you turn on a hot water tap in your house, the system’s flow sensors detect the water.

2. Controls are Triggered

The system sees it is time to produce hot water. It is set to the ideal temperature, so the burners always heat the water perfectly to avoid burns or chills.

3. Burner ignition

For gas units, a fan turns on to draw in outside air and open a gas valve, so the burner ignites.

4. Water Circulates

As the burners ignite, they heat the water by circulating it through a heat exchanger.

5. Water is Delivered

Once the water reaches the ideal temperature, the water exits the heater and flows through the pipes to the tap. Although it sounds like you have to wait for the water, it happens instantly. As long as the tap remains turned on, the heater continues to send hot water to the faucet in use.

6. Venting

Vents located in the roof or outside wall carry exhaust gasses away if you have a non-condensing tankless unit.

7. Automatic shut down

When the tap is turned off, the heater automatically turns off.

Non-condensing vs Condensing Tankless Water Heaters

Condensing tankless water heaters improve efficiency by using excess heat through a second heat exchanger. Condensation is formed with a second heat exchanger capturing and cooling heat, so it isn’t wasted heat. Instead of venting the heat outside, the heater conserves the energy, allowing it to produce more hot water than a non-condensing tankless heater. Non-condensing tankless water heaters use a single heat exchanger to heat the water.

Water flows through a heat exchanger where it is heated by exhaust gasses, but in this case, the excess heat is expelled through vents. Both tankless water heaters are very efficient, but condensing units offer higher energy efficiency for better cost savings over time. Although the unit itself is more expensive you save both on energy costs as well as installation as vents are not required.

Electric vs Gas Tankless Water Heaters

The right type of tankless water heater really depends on the homeowner. While electric tankless water heaters are less expensive for the unit, installation and better energy efficiency, gas tankless water heaters are better if you have a higher demand for hot water. If you currently have an electric tank heater, there is no point investing in costly retrofits for gas.

If you do have gas, you have to consider the capacity and what will work best for your needs. Your Anderson, SC water heater experts at Clean Flo Sewer and Septic can help you make the right choice for your tankless water heater.