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How to install, clean and maintain a tankless water heater



From hot showers to washing dishes to doing laundry, we rely on water heaters to help us live comfortably. 

Does the energy savings and efficiency of a tankless hot water heater appeal to you over a traditional tank system? Then you might want to learn more about the installation process and how to care for your new heater. 

We’ll walk you through what you need to know about these heaters, the tankless system installation process and how to maintain your new built-in system. Here are the details.


What is a tankless water heater?

A tankless water heater, sometimes referred to as an on-demand water heater, has earned a good reputation for its energy efficiency and constant hot water. These systems can help homeowners save on energy costs due to their high efficiency.

Tankless water heaters heat water as needed in contrast to traditional water heaters, which heat large amounts of water and store it in a tank. If several people in your home take a long, hot shower, you might go through the available water before the traditional water heater can finish heating more. This can result in a sudden cold shower. The continual heating of water with the tankless system eliminates this problem.

When thinking about the energy factor, you might wonder how these systems work with parts of a home that need large amounts of hot water (like a hot tub). In this case, you can install a special point-of-use heater in the location.


How to install a tankless water heater

Installing a new tankless water heater can be challenging as a DIY project because it involves hooking up the system to a natural gas line. It also requires careful work with your plumbing. 

Some areas may also require special licenses to install this water heating system. For these reasons, installing a tankless water heater is often best left to a licensed plumber. If you’re curious about the process, though, here’s what you need to know.

Before installation, make sure you have the right water heater for your home. The best way to determine this is to look at the flow rate. The “gpm” rating tells you how many gallons the water heater can heat per minute. If you see 3.2 gpm, for example, you likely have enough hot water to run a shower and a sink simultaneously. Look for a larger capacity rating if you need to use more hot water at once. 

Next, make sure you have the appropriate tools. This particular job calls for a: 

  • Drill 
  • Keyhole saw 
  • Pipe wrench 
  • Any pipes and valves required by your specific system 

Next, disconnect the old water heater. Shut off the old tank’s water, electricity and gas before removing it. Then drain any water that remains. After completing these two steps, you can safely remove the old tank from the system and get it out of the way. 

Now that you have the necessary tools and have removed the old tank, you’re ready to start the tankless water heater installation. 

Prepare the gas line hookup

Begin the process by preparing the gas line hookup. Determine if the new water heater requires a larger gas supply line than what you already have. If that’s the case, you’ll need to get a new one before going further. Tankless water heaters typically require a 1-inch gas pipe.

The gas line will run from the gas meter to your new water heater. Look carefully at your tankless water heater model to see where you need to connect the gas.

Create a fresh-air intake 

A gas tankless water heater needs adequate ventilation. These systems can produce considerable condensation that needs access to the outdoors. Use the keyhole saw to drill a hole that can allow the water heater access to the fresh air. PVC pipes can then connect the water heater to the external hole.

Connect the cold-water supply line

Next, connect the cold water to the water heater. Look for your cold-water supply line and attach it to the water heater. You should connect the water utility pipe to the inlet part of the tankless unit. As you connect your water pipes, install shut-off valves so you can control the flow of water into the system. 

Connect hot-water lines out of the unit

When the system runs, you need a connection to bring the hot water throughout the rest of your home. You’ll likely need a ¾-inch copper pipe for this connection. Connect the pipe leading to the house to the part of the unit known as the outlet.

Connect to an electrical outlet

The amount of electrical power your system requires depends on whether it’s a gas-powered tankless water heater or an electric tankless water heater. The gas unit needs to be connected to 120-volt power, whereas an electric unit calls for double that. 

Homeowners who don’t have training as an electrician might need to hire a service professional to help with this step. You’ll need the power source to be near the water heater for easy hookup. A power source needs to be wired into place if you don’t already have one in that part of the house.

Install a crossover valve

The crossover valve helps keep the hot water ready to flow whenever needed. Typically, it’s installed at the farthest plumbing fixture so the water heater’s circulation pump can do its job of preparing the hot water and keeping it ready.

Turn on the unit

Now check it to see if everything works properly. Turn on the cold-water supply first, and then turn on faucets around the house to get the water to run through the system. Then turn the water off, and clean off the internal filter to remove any debris. 

Once you’ve done this step, turn the water, electricity and gas back on so the heater can start to function. Then turn on the hot water in your home to see if it works as expected.


How to clean and maintain a tankless water heater

Keeping your tankless water heater clean and well-maintained can help extend its life span so it serves you well for years to come.

Keep in mind that the frequency with which you need to complete water heater maintenance will depend on how much the system gets used. For many homes, the tankless water heater needs servicing at least once a year. However, those who live in regions with hard water or those who keep the water temperature high may want to take care of maintenance at least twice a year.

Flush the water heater

As you use the water heater, minerals can build up inside the unit and cause damage (and increase your energy bill). Flushing helps remove this buildup.

You’ll need a vinegar and water mixture, two lengths of hose and a sump pump to complete this task. First, disconnect the power to your heater and turn off the water. Then attach your hoses to the system.

The sump pump will help you push the vinegar-water mixture into the heater. Once you’ve run the vinegar-water solution through the water heater, follow up by flushing it with regular water. 

Clean the air filter

Your system also has an air filter. To keep this clean, turn off the unit and remove the air filter. Give the filter a good cleaning with a soft scrub brush, soap and water. Ensure the air can run through the filter unobstructed. Once you’ve washed it thoroughly, give it a good rinse and let it dry completely. 

Clean the water filter

The water filter inside your heater helps trap any sediment that comes in with the water. If you allow the filter to go too long between cleanings, the sediment can build up and make it harder for the heater to work properly. 

Like the air filter, turn off the water and remove the filter. Then use soap and water to give it a good scrubbing and remove any sediment. Rinse it well and place it back inside the water heater. 


Protect your water heater from costly repairs with Cinch

Like your HVAC system, the water heater is probably one of the most important systems in your home. Cleaning and maintaining your tankless model can help keep you and your family comfortable with a steady hot-water supply.

Even with the best care, you might run into a water heater repair that you can’t handle yourself. In these cases, get peace of mind with a home warranty. Cinch Home Services offers a Built-in Systems plan that covers all components and parts of the water heater, including tankless water heaters. We make it easy to find the right coverage for your needs and can make unexpected breakdowns more manageable while protecting your budget. 

Request a free instant quote today and experience the benefits of having a home protection plan.


Properly caring for your tankless water heater can help it last longer and work efficiently. Here’s what you need to know about installation and maintenance.