Noritz Tankless Water Heater Keeps Shutting Off

Noritz Tankless Water Heater Keeps Shutting Off

Noritz Tankless Water Heater keeps shutting off due to the following reasons: 

  • Electric issues like loose wiring
  • Gas supply problems like no gas at the unit, gas meter, and gas tank. 
  • Flame sensing rod gets dirty or bent
  • Clogged heat exchanger
  • Low flow rate

Throughout this troubleshooting guide, I will walk you through every step to fix the shutting-off problem. 

So, let’s get started right here. 

Table of Contents

Noritz Tankless Water Heater Keeps Shutting Off [5 Easy Solutions]

This chapter will break down each of the culprits that causes the unit to keep turning off.

1. Electric Issues

Every time you plug your Noritz water heater and turn it on, it keeps shutting off! This is just as simple as the unit is grounded improperly or loose wiring. 

When an electrical leakage is detected, the breaker will keep tripping every time you power on your water heater. And guess what, the heater itself will also keep turning off when the breaker gets tripped. 

Using an inappropriate circuit can also cause the unit to shut off repeatedly. 

How To Fix:

First off, ensure you plug the unit into an electric outlet that delivers a sufficient amount of electric power the heater requires. 

Now, it’s time to verify you grounded the water heater properly. An electrician should perform this task. However, if you are electrically inclined, you can do it yourself by following the below steps: 

  • Remove the screw from the junction box and open the junction box cover. 
  • Attach the grounding wire to the ground screw in the cover. 
  • Now, crimp the outdoor power cable to the power cable of the water heater. 

For loose wiring or electrical leakage, I highly recommend you call a qualified electrician to handle this issue for you. 

Lastly, ensure you use an appropriate circuit so that it can meet the demand of power consumption up to 182W. 

2. Gas Supply Issue

You won’t turn on the unit if there is no continuous flow of gas at the unit, gas meter, and gas tank. 

Besides, improper type of gas can also cause the unit to not come on. Nonetheless, improper gas pressure will also be responsible for the unit to keep shutting off. 

How To Fix:

Start with inspecting that the gas is flowing to the unit trouble-freely. Ensure you turn the gas valve fully. Otherwise, it will interrupt the steading flow of fuel to the unit. 

Next, make sure you fuel up the water heater with the proper type of gas. If your water heater demands natural gas as its fuel, feed it with natural gas. 

Lastly, check the gas pressure. The gas pressure of a functional water heater should be between 5” W.C. to 10.5” WC on a natural gas operated unit. On the other hand, it should be between 8” WC to 13.5” WC on a propane operated water heater. 

I recommend you call a plumber to check the gas pressure and adjust it if needed. 

3. Dirty or Defective Flame Sensing Rod

A common tankless water heater issue that can throw a wrench into work is the dirty or damaged flame sensing rod. 

If it gets coated with carbon deposits or damaged, the flame sensing rod won’t sense the flame. And the water heater will keep turning off if the unit fails to detect the flame. 

How To Fix: 

Either cleaning the flame sensing rod or replacing it will resolve the issue. To access the flame sensing rod, follow the below steps: 

Ensure you turn the unit off. Then, remove the front cover from the unit. 

Look for any corrosion or discolored parts like flame sensing rods. So, detach the white connector attached to the flame rod and the ignition plug. 

Detaching the connectors
*Detaching the connectors*

Then, remove the screws on the sides using a Phillips head screwdriver.

Removing the screws on the sides
*Removing the screws on the sides*

Never use power tools to avoid stripping the screws. Of course, you should take extra precaution when removing as the gasket is extremely fragile. 

Cleaning the flame sensing rod
*Cleaning the flame sensing rod*

Next, carefully remove the flame sensing rod and sensor. You can use fine grit sandpaper to clean the flame sensing rod and the ignition plug. Ensure there is no carbon buildup on the probes. 

However, if the flame sensing rod gets bent, you must replace it. 

4. Clogged Heat Exchanger

A clogged heat exchanger is another caveat I blame most. When the heat exchanger gets clogged by sediments, it causes the unit to overheat. And your Noritz water heater keeps shutting off due to overheating. 

How To Fix: 

Flushing the heat exchanger will be the solution to the issue. Complete the following cleaning procedure to learn how to flush heat exchanger on Noritz Tankless Water Heater: 

1. The preparation of the flushing system: 

Flushing the heat exchanger on noritz
  • Turn the gas supply valve to the off position.
  • Close both the inlet (V1) and the outlet (V2) water valves.
  • Attach one drain hose (H1) to the drain valve and the other one to the circulating pump. 
  • Attach the drain hose (H2) to the circulating pump.
  • Connect the drain hose (H3) to the drain valve (V4)
  • Now, pour a gallon of calcium and lime based cleaning solution and a gallon of water into a plastic bucket. 
  • Open both drain valves (V3 and V4)

2. Flushing the heat exchanger: 

Flushing heat exchanger
  • Pull out the fron cover from the unit.
  • Attach the blue connector marked FLUSH for flushing on the circuit board.
  • You can see the code CCC on the data display.
  • Turn on the circulating pump to let it circulate the flushing solution through the water heater. You should keep the circulating pump turned on for at least an hour at a rate of 1.5 GPM. 
  • The water heater will throw the code C60 when it detects the flow of flushing solution. After a minute, this code will turn into C59. 
  • After an hour, the code C59 will turn into C00.
  • Turn the circulating pump off. 

3. Rinsing the flushing solution: 

  • Pull out both the drain hoses (H2, H3) from the plastic bucket. Then, place the drain hose (H3) into a sink. 
  • Close the drain valve (V3) and open the water inlet valve (V1).
  • Clean the unit with fresh water for 3 minutes or more. 
  • Close the drain valve (V4) and remove the drain hose (H3) from the drain valve (V4). 
  • Detach the drain hose (H1) from the drain valve (V3). 
  • Detach the blue connector marked ‘Flushing’. 
  • Close the front cover.
  • Set the gas supply valve to the on position and open the water oultet valve. 

5. Low Flow Rate

Every tankless water heater has a minimum flow rate to activate the unit. And your Noritz Water Heater is not an exception to that. The unit will keep shutting off if the flow rate is less than 0.5 GPM. 

How To Fix:

To fix this issue, you just need to increase the water flow rate. You can do this by opening multiple hot fixtures at once to let more water pass through the unit.


Electric issues, gas supply problems, and defective flame sensing rod are some common culprits that cause the Noritz tankless unit to keep shutting off. 

Besides, dirty heat exchanger and low flow rate can be responsible for the tankless water heater to shut off repeatedly. 

Fortunately, I broke down each of the culprits that will help you fix the shutting-off issue. What you need to do is- just follow the troubleshooting steps I mentioned and get your water heater ready to heat the water. Happy Plumbing!

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