How to Flush a Noritz Tankless Water Heater

7 Tips for How to Flush a Noritz Tankless Water Heater: The Ultimate Maintenance Guide

About Noritz Tankless Water Heaters

As a homeowner, it is inevitable to invest in your home now and then to improve your livelihood. Indeed, investment into your home should not only benefit you and the people around you but should also improve the status and outlook of the home significantly- this is a good venture as it improves the value of the property and makes it a worthwhile investment, yielding immense returns in the nearest or farthest future. Noritz is an investment if you aim to secure an energy-efficient, durable, and reliable tankless water heater.

Noritz has been an innovator in the water heating industry for over 60 years. They introduced the first modern, electronically controlled tankless water heaters in 1981 and remain the leader in energy savings and superior hot water delivery today. Most water heaters produced by this manufacturer are compact in size and flexible in their structure, making retrofitting quite easy and convenient.

Further to this, Installation requirements are quite minimal. In most cases, you may only need to ensure an adequate water supply, a venting system to effectively remove combustion, proper grounding, a condensing drain, etc. Ultimately, your new tankless heater can be installed in the same space as your old tank-based water heater, which takes up less space.

Installing a Noritz Water Heater

If you are a homeowner who does not mind getting their hands dirty, installing a Noritz tankless water heater, or any water heater, could be an interesting adventure. This installation process is nothing too complicated if you are prepared to study the manual through and through because this process requires some expertise and knowledge of plumbing and electrical connections. Below are the general steps involved in installing a Noritz tankless water heater.

Step 1: Review the installation manual

You must familiarise yourself with the installation guidelines, requirements, and safety precautions about the tankless water heater you are trying to install- this exercise will save you a lot of pain, especially those associated with determining where what goes. Moreso, ensure that it is a manual specifically made for the device you are trying to install to get a tailor-made guide.

Step 2: Choose a suitable location

Picking a suitable location for installation is another necessary consideration to be made. You have to ask yourself- will my tankless water heater be accessible for maintenance or seamless troubleshooting where it is? Does this location comply with local building codes? Etc. If you can answer these questions in the affirmative, your Noritz tankless water heater may be in the appropriate location.

Step 3: Prepare Utilities such as;

Gas Supply: Confirm that you have an adequate gas supply line with the correct pipe size and pressure rating. Following local codes and regulations, install a sediment trap and a shutoff valve.

Water Supply: Provide a dedicated cold-water line with isolation valves for the tankless water heater. Consider using a 3/4-inch line for optimal flow.

Electrical Connection: Ensure you have the correct electrical voltage and amperage. Follow the manufacturer’s instructions for wiring the unit to a dedicated electrical circuit.

Step 4: Install a venting system

Determine the appropriate venting type (direct vent or Category III stainless steel vent) based on the model and your home’s layout, and install it appropriately according to the user’s manual.

Step 5: Mount the water heater and connect the utilities

In this step, all you have to do is to mount the water heater and connect all the utilities.

Step 6: Install condensate drain

If your model requires a condensate drain, follow the manufacturer’s guidelines to install the drain pipe. Ensure proper slope and termination of a suitable drain system.

Step 7: Test and check for leaks while you perform initial startups.

Right before the initial startup you have to perform certain tests. Carefully check the leaks. If you are satisfied with the test then move on otherwise fix that first.

How To Flush a Noritz Tankless Water Heater

A Noritz water is great in its performance. Indeed, it possesses some interesting features that give you your money’s worth; however, when necessary maintenance measures are not taken effectively and regularly, you may soon experience a dip in performance. One of the maintenance measures you must regularly implement is flushing your tankless water heater to clear off debris and mildew that may be stuck on the water heater. Follow the step-by-step guide below to flush your Noritz tankless water heater.

Step 1: Turn off the power

Do not try to be a hero without first considering your safety. Your safety should always be primary when you flush your water heater. Go to the breaker that turns your unit on and off and put it off. You may also disconnect the power cord and follow the safety precautions prescribed in your manual for further necessary safety measures.

Step 2: Shut Off the Water Supply:

If water finds its way into your unit while flushing is on, it may disturb the process. Hence, shut off the water supply to the unit by turning off the valve on the cold water line leading to the water heater. This will prevent water from entering the unit during the flushing process.

Step 3: Prepare Flushing Solution

Prepare a descaling solution by mixing white vinegar and water in a 1:1 ratio. For example, mix equal vinegar and water in a bucket or container. This method is also quite effective for removing grease and stains from a stainless steel appliance.

Step 4: Connect Noritz Flushing Kit

Noritz flushing kit usually comprises a hose, a circulation pump, and other items found in an appliance repair kit, like a screwdriver, a wrench, etc. Hence, follow your user’s manual to determine how to connect the flushing kit to your tankless water heater, as they vary according to models.

Step 5: Open Service Valves

Locate the service valves on the tankless water heater. These are usually located near the isolation valves. Open both service valves to allow the descaling solution to flow through the unit.

Step 6: Start the Circulation Pump

If your flushing kit includes a circulation pump, turn it on to initiate the flow of the descaling solution through the tankless water heater. Ensure the solution is circulating through the unit and all the internal components. To allow thorough circulation throughout the internal parts of the water heater, you may wait it out for about 40 minutes and rinse it out with fresh water.

Step 7: Shut service valves and reconnect the water supply

Now in this step shut all the service valves. After that reconnect the water supply to move to the final step.

Step 8: Final Inspection

This is the final step. Once you find everything is as per the guidelines and working fine and you check for leaks or other latent faults now all you have to do is to restore the power.


How do I descale my tankless water heater?

To descale a tankless water heater, mix equal parts of white vinegar and water, connect a circulation pump or flushing kit to the unit, circulate the descaling solution through the heater for the recommended time, rinse with fresh water, and restore the water supply and power. Refer to the manufacturer’s instructions for your specific model.

What do I need for a Noritz tankless water heater flush?

To flush your Noritz tankless water heater,  you need the following items: 

1. Flushing Kit: A flushing kit for Noritz tankless water heaters. This kit may include hoses, valves, and adapters needed for flushing.

2. Descaling Solution: A descaling solution, often made by mixing equal parts of white vinegar and water, is commonly used to remove mineral buildup from the unit’s internal components.

3. Buckets or Containers: These are required to mix the descaling solution and collect the flushed water during the process.

4. Tools: Basic pliers or wrenches may be needed to connect and disconnect hoses or disassemble the water heater.

How do I contact Noritz America technical support?

You may visit the Noritz America website – Locate the support or contact section of the website, and look out for their contact details, a phone number, or an email address specifically designated for technical support inquiries. Use the contact details to get in touch with them.

Where do I find Noritz tankless water heater manual?

The Noritz tankless water heater manual is on

How to descale a Rinnai tankless water heater?

To descale a Rinnai tankless water heater, you can use a Rinnai-specific descaling solution or a mixture of equal parts white vinegar and water. Connect a circulation pump or flushing kit, circulate the solution through the heater for the recommended time, rinse with fresh water, and restore the water supply and power. Consult the Rinnai installation and maintenance manual for detailed instructions. You may learn how to flush a Rinnai tankless water heater here.