So, How Do Tankless Water Heaters Work?

Sep 7, 2020

You’ve heard of tankless water heaters and you may even have one of your own, but do you know how they work? 

According to, a typical household using a tankless water heater saves 24 to 34 percent more energy than a conventional water heater. Not only are these clever systems more efficient than conventional water heaters, they also save space and money. What makes this possible? Let’s talk about why more people are making the wise decision to switch to tankless. 

Tank Vs. Tankless Water Heaters 

Conventional Water Heaters

First, let’s start with an overview of a conventional water heater. These water heaters tend to be rather large in size (usually at least five feet tall and two feet wide), requiring quite a bit of space in your home or place of business. And if you live in California, you most likely do not have a basement to store these tanks in – you would need to stash this tank in a closet. Along with its hefty size, it holds anywhere from 20 to 80 gallons of hot water. Did you know –  tank storage heaters continuously heat and reheat water throughout the day – whether or not you have a hot water tap turned on? In other words, you’re paying for hot water that you don’t use. 

Tankless Water Heaters

Tankless water heaters, on the other hand, never run out of hot water. They provide instant hot water when you need it – hence its other name, “on-demand water heaters.” Tankless water heaters can provide 13.8 gallons of hot water per minute on demand. They are smaller in size (about 2 feet tall), thus not requiring a lot of space. Unlike conventional water heaters, on-demand water heaters can be installed outside your house or place of business. And, most importantly, they save energy because they do not produce unnecessary hot water when it’s not needed.

In addition to the technical features of both conventional water heaters and on-demand water heaters, they also differ in lifespan. Conventional water heaters typically last between 10 to 15 years. Also, they tend to require more repairs and need to be “flushed out” at least once a year – which can take up to 45 minutes. On-demand water heaters have a lifespan of over 20 years. 

Tankless water heaters save – energy, space, and money. And, they also save you valuable time and avoidable stress.

The Process of Tankless Water Heaters

That brings us to the process of how tankless water heaters work. As simple as this sounds, you turn on a hot water tap. Once your hot water knob is turned on, the cold water immediately flows through the pipe and enters the water heater. The heating process will begin by either an electric heater or a gas burner heating up the water (natural gas is preferred). Simultaneously, cold water flows through sensors. Once the internal computer is triggered, it creates the perfect temperature. Water then circulates around a heat exchanger until it reaches the designated temperature (adjusted on the water heater). Once there is not a demand for hot water, (e.g. the hot water tap is turned off)  it shuts down and conserves energy. And voila – now you are an expert! 

Ready to Go Tankless? 

Arnett’s Water Systems makes it a priority to sell the highest quality tankless water heaters in the industry to our valued customers in San Diego County. Our service does not end with installation – we also provide maintenance services as needed. 

As experts in the field with over 25 years of experience, we will help you decide which tankless water heater model works best for your specific needs.  

We make it easy to purchase our premium tankless water heaters. All estimates are free. Give us a call today and we’ll take care of you!

Infographic for process of tankless water heater