Noritz Tankless Water Heater No Hot Water [Why + How To Fix]

A tripped circuit breaker or the bad heating element is the main culprit behind your Noritz tankless water heater’s no hot water. Whatever, try to fix the hot water issue by resetting the fuses on a circuit breaker or replacing the heating element.

noritz tankless water heater no hot water

If the above effort doesn’t resolve the problem, surely there might be other issues with sediment build-up, low water flow, or gas pressure.

Fortunately, we have already identified the reasons behind the issue. So, go on to read this extensive guide to get quick solutions to your problems.

Table of Contents

Noritz Tankless Water Heater No Hot Water [Reasons + Solutions]

Here, we will find out the leading reasons that prevent your Noritz tankless water heater from producing enough hot water and explain their easy solution. So, let’s scroll down…

noritz tankless water heater

Note: You can also read how to fix noritz tankless water heater making loud noise.

1. Tripped Circuit Breaker

A tripped or malfunctioning circuit breaker is one of the main culprits for your tankless water heater having no hot water.

Mechanically, a gas or electric heater performs excellently, depending on a dedicated electrical circuit. As usual, a breaker trips for safety measures.

tripped circuit breaker

But when you have no hot water with your heater, it indicates that the breaker box has malfunctioned due to a surge of electricity or shorted fuses.

Actually, a tripped circuit hints that the current flow was interrupted. Whatever, let’s have a look at how to fix it.


In this case, if you find a hot water issue with your circuit breaker, open the breaker box to see if it has tripped.

If this happens, you won’t get the circuit in the same position as others, turn the breaker off and then back ON position again. Now, just wait until your water heater heats back up.

But when your heater’s breaker trips frequently, the reset function or high-temperature cut-off switch of the heater may have been affected.

So, reset your breaker function to resolve the breaker’s issue, and the procedures will restore the power of your heater. Let’s know the steps to reset the breaker.

How To Reset Your Circuit Breaker

  • Flip your breaker to the “off” position to avoid any risks of electrocution.
  • Remove the upper cover of the heater without hurting any wiring.
  • Find the red reset button behind isolation.
  • After locating it, just press and hold down the “Reset” button until it clicks and then releases it.

Hopefully, the breaker system of your heater will be back working in order to produce hot water. If there are no major issues with the breaker, probably the heating elements have failed. 

2. Faulty Heating Elements

There are two heating elements in your Noritz tankless water heater. One is an upper heating element, and another is a lower heating element.

Whenever you’re turning on your heater for hot water, cold water pushes to the bottom of the heater and is heated by the lower heating element.

 faulty heating elements

Then, it rises to the top, the upper heating element heats the water to the desired temperature.

But your tankless water heater is not hot enough when any of the elements fall down to perform their job properly. And then you will definitely experience cold water instead of getting hot water.

Besides, the lower element could be faulty because of accumulating sediment. And then, the thermos can’t measure the water temperature. Plus, this may somehow occur because of short electrical wiring.


When you run out of hot water, first you have to make sure whether the heating elements are fine or damaged. So, now test the element’s status by following 2 steps.


First, turn off the power to your heater and let it cool completely. If you find a loose wire connection, you just need to reconnect the wires and tighten them fully.

But when it becomes rusty, clean it with compressed air. While there is no case of an electrical surge, check the heating elements internally.


To ensure the element’s functionality, open the heating components area and locate the elements to identify what is wrong with your heater. Now, take a digital multimeter.

When you keep the multimeter, one leads to the element terminal and the other to the second terminal. You will get a resistance of 10-30 ohms when the components have continuity, otherwise, it is faulty.

If you are not good at handling the case, call a certified plumber to inspect the issues. Whatever the case, he will surely find out the issues and solve them. If needed, you might replace the heating elements.

Note: When there is an issue with heating elements, the problem might be with building sediment in the unit.

3. Accumulation Of Sediment

Your Noritz tankless water heater isn’t heating water because of accumulating sediment in the water supply line.

When you’re living in a hard water area, the hot water supply line might be clogged by minerals and magnesium deposits that can ruin the performance of your heater’s hot water pipes throughout your home.

Because calcium and the high-mineral build-ups inside your heater react like an overloaded issue. 

descale accumulation of sediment in noritz water heater

Plus, this issue forces the heater to work under pressure. Typically, a tankless heater heats water directly to supply hot water. But water can’t pass easily through the lines because of accumulating hard sediments.


For this case already, we have identified that you are experiencing cold water flow due to the build-up of sediment inside your heater. Here, calcium and minerals are the major villains causing this issue. 

So, to prevent building up any sediments in your heater, regularly check the water filter for debris and blockage. Because the water contains minerals and calcium that can cause a quicker buildup of debris.

That’s why it prevents your water from running through the narrow path of the heating elements. Check out it periodically or debris can be trapped along this long path and stop your filtering system.

Now, to remove sediment, flush or drain out your water heater after every six months. For this purpose, you can use a water softener to protect or slow the buildup process.

And, you should descale your water heater at least once a year to protect your appliance from dying before its average life. 

You can watch the below video to descale your Noritz water heater. Hopefully, you will get rid of the sediment-building issue inside your heater.

4. Leakage Issue

Your tankless water heater won’t heat the water if there is any leakage between the water heater and the heater’s unit.

Even a leak can cause your Noritz heater to stop producing hot water. Our water heater troubleshooting experience proved that there are three types of leaks in a water heater, such as:

leakage with pipelines
  • Gas Leak
  • Leakage with pipelines
  • And leaking in the water heater tank

However, whatever the leakages, a gas leak is a matter of concern when the heater doesn’t supply hot water. This crisis may happen when the temperature and pressure release valves are defective because of too much pressure. 

If it occurs, the heater won’t get enough gas pressure to heat the water. Besides, this process can ultimately shut off the main valve of your heater. So, whenever you notice a gassy smell like rotten eggs in your house, be sure that there might be a leak in the gas line.

Structurally, tankless water heaters aren’t designed to leak easily. But unfortunately, this may occur with the valves and pipelines. If you find water on the ground of the compartments, there might be a leak in the tank. Therefore, your heater can’t supply enough hot water.


To fix the leakage issue, analyze your heater’s connections, including its valve and pipelines. If you notice the connections are secured, make sure the compartments of the tank are faultless.

But if you identify leakage in a gas line, you will notice a gassy smell. After finding a gas leak, turn off the gas valves immediately. Don’t attempt to maintain the leaky gas line. Because this leak is risky to repair, so, inform your gas utility company ASAP.

Take help from a professional plumber to replace the faulty parts. He will inspect and install a new gas valve to protect against leakage.

Then, check for pressure release valves and leaks in supply lines. If it happens, install a water expansion valve to release the pressure of the flowing water. This step will also protect your device from any future dangerous explosions.

If the process doesn’t work still, replace the faulty pipelines and the release valve ASAP. Your heater isn’t supplying hot water even after replacing the pipes and valves. Be sure your water gas valve might malfunction.

5. Defective Gas Valve

When there is no issue with leakage, the gas valve is mainly responsible for not providing sufficient gas pressure to heat the water. If you have a gas tankless water heater that has no hot water, check the inlet valve and gas supply line.

defective gas valve

In this case, if your gas valve has broken or the gas line has leaked, the low gas won’t heat the water properly. So, to ensure enough gas supply, the valve should be secure and stay in the right place. Plus, when your gas line is restricted, it prevents the pilot light and flame from igniting.


Once you have turned on the hot water faucet but have no hot water to use. To find the reason, double-check if the gas supply is on with super pressure and if you have paid your gas bill. Then, make sure the gas inlet valves are fully open in the right position.

Secondly, if that isn’t an issue, turn on the inlet valve until it reaches the same distance as the gas line. Consider allowing some time for gas to enter the unit before relighting the pilot.

Next, investigate for any blockage in the gas supply line. After finding any blockage, shut off the gas valve and try to clear it out in order to get it back in working condition.

Finally, when there is no gas leakage, possibly, the gas valve breaks itself. So, your parts needed to be replaced with new ones. Don’t try DIY. Shut off your heater and call an expert plumber to handle this as an urgent case.

6. Too Low Water Flow

You have entered the washroom, but there is no hot water to shower. This situation is really uncomfortable and painful, especially if you have any urgency.

too low water flow

You are facing this underperforming system because of its slow flow rate. You might face such a crisis when multiple showers are using the hot water fixture for showering, cleaning dishes, or drying towels at the same time. This situation hints that your heater has crossed its limit due to overloading the system.

As a result, the system isn’t getting a chance to pump out hot and the unit will stop supplying hot water. And even it can shut down altogether whenever you need hot water. This is a “cold water sandwich” and it occurs because of too many showers at a time.

Typically, tankless water has a limited capacity to produce hot water. Once the limit is crossed, it may take time to heat more water.


To solve the issue,  first, try to reset your unit. We will guide you at the end of this article on how to reset your heater.

Second, pay attention to reducing the demand for hot water by limiting the use of many appliances at once and waiting a few minutes if you have a large household. In this situation, turn off extra taps until hot water returns to the unit.

However, if you find your heater couldn’t hold enough water as per your demand and your heater is getting overloaded frequently, consider either upgrading a unit with a higher capacity or adding a second unit to resolve the issue. Though this system is expensive, it ensures long-term service and you won’t have to wait for hot water.

7. Ignition Failure

Ignition failure is like a flame failure. When the above factors aren’t responsible for water issues, ignition failure might be a major culprit then. Because, without proper ignition, you can’t expect to run your heater, let alone get hot water.

noritz tankless water heater ignition failure

Functionally, your heater will display an error code of 11 that indicates the failure of the ignition. This means there is either an issue with the gas supply or a gas valve. Besides, your heater won’t ignite if:

  • There is low propane or gas pressure or an unpaid gas bill.
  • The gas and water valves aren’t fully open.
  • Gas regulator failure.
  • Combustion and venting issues
  • And, narrow gas lines.

Your Noritz tankless water heater is not hot enough when any of the issues prevent the heater from igniting. However, in most cases, you can fix the issues by yourself.


In order to reignite your heater, make sure that your propane tank is full of gas before investing in any other parts. Recheck if the water and gas valves are fully open. Then check that the ignition pack is performing properly.

Basically, a tankless water heater needs a fresh air supply to run smoothly. So, inspect all vent pipes to ensure they are connected properly and have no puncture holes. Clear the dust and debris created by a bird’s nest or rodents that may block the venting system.

If the above tips don’t work well, call an expert to help you troubleshoot the issue and replace the parts if necessary.

8. Too Old Water Heater

When none of the above reasons are responsible for running out of hot water, your Noritz heater has probably become too old.

old noritz water heater

Normally, a tankless water heater’s life span is 10–12 years for the best service for your home. But any of the parts start to maltreat if it gets too old. Keep in mind, many of our heaters are getting unfit because of lacking care.


Try to identify the faulty areas. If it goes under maintenance, repair it. Remember, whether your heater is unfit due to lacking periodic maintenance.

If so, pay attention to proper maintenance and repair that can keep your heater working in good order for a long time. Because there is no alternative to periodic inspection and maintenance, it will save you money and time.

Finally, if your heater reaches the end of its lifetime, there is no option left for you but to replace it with an intake one.

How To Reset A Noritz Tankless Water Heater

Your Noritz tankless heater has a reset button. And, you can simply fix most of the common problems instantly by resetting your heater. Let’s follow the instructions to reset your heater.

First, locate the red reset button near the side or front of the unit and verify if the button is in “reset” mode. Then, press the reset button once more to get into reset mode. 

Now, the light will change from red to green if it is done correctly. Wait for 10 seconds before going to the next procedure.

Next, turn the control knob that will allow you to increase the temperature of the thermocouple. So, turn it until it reaches the highest temperature setting. Once again, wait for ten seconds, and don’t try turning anything else on that requires hot water.

After that, check for a power outage. Because the breakers may be in a neutral position for safety. If you notice any circuit breakers have tripped, just back to their position to come back on. Finally, turn on your heater and wait until it comes back into working mode. Hopefully, your heater will run as usual.


How does a tankless water heater produce hot water?

Tankless water heater constantly heats water except using any storage tank. After turning on the heater, cold water flows through the heat exchanger to the unit. Then, either the gas burner or electric elements heat the water. 

How long does a tankless water heater take to supply hot water?

A tankless water heater directly heats the water to supply endless hot water. It takes about 15 seconds to reach the desired temperature. Just wait until it reaches your hot water faucets.

What ideal temperature should I set with my thermocouple?

You can set the thermocouple temperature up to 120-140ºF. But 120ºF (or 49ºC), is the ideal and recommended setting for the best performance.

How much water can a tankless water heater supply?

Normally, a tankless water heater can supply 2–5 gallons of hot water at a rate per minute. If you face a low rate of hot water, there is an issue with your water flow units/sensors.

Why is my tankless water heater getting excessively hot?

Your tankless water heater might overheat if the system doesn’t get enough cold water to absorb the heat it generates. Plus, restricted valves and insufficient air supply are responsible for being too hot.


Now, it’s clear to you why you aren’t getting hot water from the Noritz tankless water heater, as we have mentioned in the guide.

So, whenever you struggle to get hot water with your tankless water heater, keep in touch with our guide to get an instant solution.

Yet, if you face any issues fixing your problems, don’t hesitate to leave feedback for us. It is our pleasure to reach out to you with a possible solution.

About Phillip

Phillip is an HVAC guy & has convenient skills in the fireplace, heater, stove & other heating systems. He has been working and writing in this field for the last 5 years. He is really passionate about writing & share his expertise through his writing to help others. More about us.

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