Kaitlyn Schott

By: Kaitlyn Schott on October 23rd, 2021

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Tankless Water Heaters: A Beginner’s Guide

Standard Water Heaters | Tankless Water Heaters

You’re in your shower. Water pitter-patters at the back of your neck, but it isn’t hot. It’s not even lukewarm anymore. The water is ice cold after ten minutes, and you’re glaring a hole into your wall. You angrily wonder if you should have waited longer to take your shower after your significant other. No. You didn’t want to risk being late to work with the traffic on the 110 (the busiest highway in LA).

You try to take deep meditative breaths, but it doesn’t work—the irritation pricks at the back of your throat. You finish your shower quickly and start rethinking your shower schedule for what seems like the hundredth time.

If you’re sick of not having enough hot water, you may want to consider a tankless water heater. At Monkey Wrench Plumbing, Heating & Air, we’re certified by some of the top tankless water heater manufacturers like Navien, Takagi, and Noritz, so we can thoroughly teach you about this high-tech piece of equipment.

We promise this beginner’s guide will help you learn all about tankless units in easy-to-understand terms. You will learn all the benefits of a tankless water heater, its parts, and how it works. We will also give you resources to expand your knowledge about tankless water heaters.


What’s a Tankless Water Heater?


Tankless water heaters are high-tech water heaters that don’t hold water. Instead, tankless water heaters heat water as it passes through the unit. Because of this, tankless water heaters give you:

  • Unlimited hot water - Having a tankless water heater means you can have all the hot water you need, and you never have to worry about running out.

  • Reduced monthly bills - Tankless water heaters only heat water when you need it as opposed to traditional water heaters that heat water all the time.

  • More space - Tankless water heaters take up a fraction of the space bulky tank water heaters do so that you can use your space more efficiently.

  • Curb appeal - Tankless water heaters are sleek and attractive compared to conventional water heater units. They will give your home an updated and modern look.

  • Guaranteed results - Tankless water heaters are durable, so when they are correctly installed and maintained, they can last 20-25 years. They also stand up to the elements well and won’t flood your house if they break.

It's important to note while a tankless water heater gives you endless hot water, it does not give you instant hot water.


A Noritz tankless water heater installed by Monkey Wrench Plumbing, Heating & Air.

A tankless water heater installed by Monkey Wrench Plumbing


The Parts of a Tankless Water Heater


To fully understand how a tankless water heater works, we’ve broken down its main parts into two categories. They are:

  1. The startup stage - Parts in this stage operate before any water is heated.

  2. The heating stage - Parts in this stage heat the water and give you water.

Let’s take a tour of a tankless water heater.

The Tankless Water Heater Startup Parts

  • Control panel - This screen shows the max temperature of your water and error codes in the event the unit stops working.

  • Cold water mainline - This pipe gives you access to water from the city.

  • Flow sensor - This sensor alerts the tankless water heater when water is flowing.

  • Computer board - This computer chip is the heart of your tankless water heater. It allows you to get hot water on demand.

  • Fan - This fan pushes fumes out of the unit.

A Navien tankless water heater displaying a max temperature of 120 degrees Fahrenheit on the control panel.

Navien tankless water heater

The Tankless Water Heater Heating Parts

  • Gas inlet - This pipe allows you to access gas from the city to heat your water.

  • Burner - This part heats the water for your fixtures.

  • Exhaust - This pipe vents the fumes from the burner.

  • Heat Exchanger - This chamber contains a tightly spiraled pipe that keeps the water over the burner.

  • Bypass valve - This valve lets water out of your tankless water heater and keeps water from back flowing into your unit.

  • Hot out - This pipe connects to your fixtures and delivers you your hot water.

Inside tankless water heaters from Noritz and Takagi


Inside a tankless water heater by Noritz

Inside a tankless water heater by Takagi

As you can see, the layout of a tankless water heater’s parts differs by brand. However, these water heaters function relatively the same way.


How a Tankless Water Heater Works

Now that you know the parts of a tankless water heater, we’ll walk you through how it works.

  1. You turn on your hot water fixture. The water that comes out will be cold at first. This is the water left in your pipes (between your fixtures and the bypass valve) that cooled down between uses.

  2. Cold water enters your tankless water heater from the mainline and passes through the flow sensor.

  3. The flow sensor alerts the computer board that water is entering the water heater.

  4. The computer board then turns the fan on, and the gas valve opens. You may hear a clunking sound as this happens, don’t worry, this is normal!

  5. Once gas flows into the unit, the burner roars to life.

  6. The cold water enters the heat exchanger and goes through a series of tight bends in the pipes to get up to the temperature set on the control panel.

  7. After the water reaches the correct temperature, it exits the heat exchanger, passes through the bypass valve, and comes out of your fixtures.

  8. Once you turn your fixture off, the water in the hot water pipe eventually cools down.

Tankless water heaters go through this process any and every time you use hot water. 


A sink pouring out water

Learning More About Tankless Water Heaters

Tankless water heaters are a great alternative to traditional water heaters that can give you endless hot water. These water heaters can provide you with this benefit along with many others because of their complex system of parts.

Now that you know the basics of a tankless water heater, are you ready to dig deeper into learning about them? We’ve created these additional articles to help you become your home’s tankless water heater expert.

Want to learn more about who we are? Read our article Monkey Wrench Plumbing, Heating & Air: 5 Core Values. And if you want to get a tankless water heater as soon as possible, call us or book an appointment online.