Why Is My Tankless Water Heater Not Working

Tankless Water Heater Not Working or Heating? Here’s What to Check First.

Tankless water heaters are energy-efficient, need little maintenance, and are relatively long-lasting in their performance. However, much like any other item, they are not fully impervious to malfunctions. They may experience small issues from time to time, such as running out of hot water or the fireplace not working. Tankless water heaters, also known as demand-type or instantaneous water heaters, are designed to supply hot water only when it is necessary. They do not generate the standby energy losses typical with storage water heaters, which can result in significant savings in energy costs.

Whenever a hot water tap is switched on, cold water is sent into the unit through a pipe from outside.

Consequently, tankless water heaters are able to provide a continuous supply of hot water.

The output of a tanklesswater heater, on the other hand, is limited in terms of flow rate.

What exactly is the problem when there is no hot water in the house yet there is cold water?

In order to get to the source of the problem, you should ask yourself the questions below.

How many appliances am I running at once?

Most likely, if you’re running the dishwasher, doing a load of towels, and taking a shower at the same time, you’re pushing the limitations of your water heater. Select the hot water activity that you require at this time, turn off the others, then restart your unit to complete the task. Many times, this is simply due to a slew of faucets being turned on at the same time, such as your shower and the kitchen sink. For example, having a shower while also running the dishwasher at the same time might cause a tankless water heater to reach its maximum capacity quickly.

You may also install separate tankless water heaters for equipment in your house that need a lot of hot water, such as a clothes washer or dishwater.

Am I reaching my minimum flow rate?

Flow rate is defined as the quantity of water (in gallons) that must pass through the tankless unit per minute in order for it to create hot water. It is likely that the unit is shutting down as a precautionary step if you are requesting less than the minimum flow rate specified. Increase the amount of water that comes out of your faucet and wait to observe whether the water begins to heat up. Tankless water heaters must be able to detect the presence of water flow in order to begin operating properly.

This is the lowest minimum flow rate available in the industry, which is a significant advantage.

Tankless water heaters that run on natural gas have higher flow rates than those that run on electricity. Even the largest gas-fired model, on the other hand, may not be able to provide enough hot water for many simultaneous usage in a large family on occasion.

Is something plugged up?

Remove any debris from your vents and air intake tubes to ensure they are not blocked. Fortunately for you, most tankless water heaters are equipped with warning devices that alert you if an exhaust vent is obstructed in any way or location. Check to see that everything, both inside and outside, is clear of obstructions, dustbunnies, and other debris. Burners that are clogged with dirt are another cause of obstruction. Make certain that they are free of debris!

What about my power source?

If you’re using power, make sure your main electrical panel is working properly. It’s possible that anything caused the breaker to trip, necessitating a reset before your tankless water heater would function properly again. If you’re using gas, check to see that your account has been paid, that you have propane in your tank, or that your gas valve is fully in the ON position.

Is it cold outside?

If your water pipes freeze over during the winter, you may be unable to provide hot water to you or your appliances. Thaw your pipes in a safe and natural manner before attempting to get any hot water again. So what if you’re dealing with the inverse of the problem? If your water is getting too hot, these are the things you should do to cure it:

  • Stop overtaxing the system by pressing too many buttons at the same time. Set the temperature of your water heater to around 120 degrees Fahrenheit. Adjust the location of your temperature sensor in order to obtain a more accurate measurement. Inspect and clean the inlet filter on your tankless water heater. Follow the installation instructions provided by the manufacturer for your model. IMPORTANT: Whatever type of tankless water heater you have, make sure to turn it off and allow it to cool completely before performing any DIY work on it. Remove any stumbling blocks once more. A reduction in water flow might lead any heated water to become excessively hot.

A malfunctioning heater element is an issue that is exclusive to electrically powered water heaters alone. Electric water heaters can be fitted with one or two heating elements, depending on their size. If a heating element begins to ground out, it will remain on all of the time and overheat to dangerously high temperature levels. Naturally, the end consequence will be uncomfortably hot water – and that’s only to get things started! The heating element will eventually burn itself out totally over time.

  • It’s the dreaded cold water sandwich, and it’s something that happens all the time in the shower.
  • Those hot water sensations you’re experiencing at first are due to leftovers from the prior user.
  • Then, once the heater has completed its task, you will have hot water once more.
  • Using a modest storage tank to provide hot water while the tankless unit is heating up can avoid this cold water sandwich from occurring again.
  • Tankless water heaters are notorious for having this problem.
  • However, because a tankless heater requires some time to heat up the exchanger, some cold water may pass through the exchanger and reach the consumer during that period.
  • Due to the fact that gas heats up virtually instantly, but electric heaters may take a minute or two to achieve the appropriate temperature for heating, gas is the preferred fuel for space heating.

If your unit is discolored or smells nasty, it’s possible that mold, fungus, or bacteria are developing within it and causing it to malfunction.

This odor is generally generated by sulfate bacteria, which can grow in the tank over time.

The magnesium is broken down by the soft water, which results in the production of sulfate gas within the water heater.

When enough sediment accumulates, the water becomes hazy, yellow, brown, and foul-smelling.

The use of a pre-made descaling solution or normal distilled white vinegar to flush your tankless water heater should resolve your issue.

If you are aware that you have hard water issues, ask us about water softeners to assist keep your unit in peak operating condition as well.

Some DIY sources may propose draining and flushing the tank, which is not always the case.

It is necessary to ensure that the gas pressure delivered to your tankless heater is enough.

Check any sensors, wiring fuses, and electrical components to make sure they have not been damaged or burned out completely.

It is impossible for the burner to ignite if the flow rate is too low.

The following are the ignition failure codes that have been seen on several tankless brands: Tankless Water Heater by Takagi – Error Codes 111, 11 or 3 a Rinnai electric tankless water heater has encountered an error code of 11.

The failure of an ignition system on a tankless water heater can occur with any brand and type, regardless of how complex or basic it is. An internal fault with the water heater or an external problem might both cause the failure.

  • Check to see that the gas and water are turned on, and that the power (120 VAC supply) is turned on. Check to verify that the right sort of gas (natural gas or LP) is being used. Check to ensure that the pressure is within specifications. Check to verify that all air has been sucked out of the gas line before and after the installation
  • Make certain that the plumbing is installed appropriately, in accordance with local codes and manufacturer’s instructions. Check to see if the water pressure is within specifications. Make certain that the water is not excessively hard (more than 7 grains), since this might result in sediment build-up. If you live at a higher elevation, check to see if the water heater is adjusted appropriately or according to the manufacturer’s specifications. And last but not least, is there an error code

Valves and plumbing connections that are leaking in your water heater are the most common source of water leaks. If you find a leak, try to locate the source of the leak inside the plumbing system. If the problem is not immediately apparent, it is recommended that you turn off the water to your water heater and contact a local plumber in your area to come assess the issue. Please contact us if you have tried these DIY remedies and are still having problems. We are also happy to assist you with a completely other issue.

There is no tankless water heater that our plumbers in Northwest Arkansas, Southwest Missouri, or Fort Smith cannot repair or install.

Please contact us!

3 Tankless Water Heater Problems (and How to Solve Them)

Do you have a tankless water heater that isn’t working correctly? If that’s the case, we’re here to assist you. In this essay, we’ll cover the following topics:

  • Three frequent tankless water heater concerns are as follows: The nature of the problem that is causing these concerns
  • How to resolve those difficulties

Do you require skilled tankless water heater assistance? Simply get in touch with us.

1. “My tankless water heater runs hot, then cold, then hot again.”

A “cold water sandwich,” as it is known in the tankless community, is the starting point of this problem. The heat exchanger (the component responsible for heating the water) takes a long time to warm up, which results in this problem occurring. You’ll receive a short burst of cold water before it’s totally warmed up and ready to start heating the water. As soon as the heat exchanger reaches operating temperature, a constant stream of warm water is delivered. How does the initial burst of hot water arrive?

It’s true that, in most cases, there is still hot or warm water in the faucet from the appliance’s previous hot water run.

How to solve the problem:

If you experience the “hot water, cold water, hot water” surprise, speak with a specialist to determine if you should combine your tankless unit with a “small” tank water heater to avoid the problem. While the heat exchanger in your tankless water heater is warming up, you may use hot water from the small tank water heater. This eliminates the dreaded “cold water sandwich” and significantly reduces the amount of time you spend waiting for hot water.

2. “I’m not getting any hot water from my tankless water heater.”

If you experience the “hot water, cold water, hot water” surprise, contact with a specialist to determine whether you should combine your tankless unit with a “small” tank water heater to prevent this from happening. While the heat exchanger in your tankless unit is heating up, you can use hot water from the tiny tank water heater. Using this method, you will avoid the “cold water sandwich” and will significantly reduce your hot-water wait time.

  • Issues with the gas supply
  • A plugged heat exchanger (due to hard water)
  • A clogged vent or air intake
  • Dirty burners
  • And other factors.

How to solve the problem:

Start by merely running one hot water appliance at a time to see how that works. If you are getting hot water even when only one hot water appliance is operating, see a plumber to determine whether you need to upgrade to a tankless unit with a greater flow rate.

If you have a gas tankless unit and you are experiencing no hot water when only one hot water appliance is running, conduct the following checks:

  1. You’ve paid your gas bill (since your tankless water heater cannot heat water unless there is a consistent supply of gas! )
  2. If your water heater vent is not clogged (be careful—these are typically placed on the roof), check the following: This means that the gas valve that supplies your tankless unit is turned on, not off. You’ve decided to schedule regular maintenance. Other tankless issues will be caught or prevented if you have frequent maintenance performed. In addition, your plumber may propose that you install a water softener to counteract hard water.

Still haven’t gotten any hot water? Have an expert check the device to determine the source of the problem and provide a solution.

3. “My tankless water heater shuts off during showers.”

This is most certainly the case if you have an older tankless water heater (10 years or older). The problem is most likely caused by the minimum flow rate being set too high. Per tankless water heater has a minimum “flow rate,” which is defined as the quantity of water, measured in gallons, that the tankless unit need to flow through it every minute (gpm) in order to create hot water. If the amount of hot water you’re requesting is less than the minimum flow rate for your unit, it’s likely that your unit is shutting down automatically as a safety measure.

See also:  How To Determine Size Of Water Heater

As a result, in order to prevent damage to the heat exchanger (as well as scorching you with extremely hot water), your tankless unit will automatically shut down, leaving you with cold water in the middle of your shower.

How to solve the problem:

If this is a recurring problem, see a plumber to determine whether you should upgrade your unit. Most older water heaters have a minimum flow rate of 1/2 to 3/4 gpm at their lowest setting. Newer units, on the other hand, have extremely low minimum flow rates (as low as 14 gpm), which means that your unit will continue to operate even when there is just a tiny demand for hot water.

Need professional tankless water heater repair in Phoenix?

Simply get in touch with us. We provide plumbing repairs 24 hours a day, seven days a week by qualified, environmentally conscious plumbers you can trust.

Why Is My Tankless Water Heater Not Heating?

Tankless water heaters often provide a number of advantages under normal situations. These sorts of water heaters are well-known for saving households money while also producing hot water more fast than other types of water heaters do. However, if your tankless water heater is not heating effectively, it may make for a very miserable day—especially if it fails to function when you have friends or other visitors around. In the event that your tankless water heater is not heating, there are various possible explanations.

Sediment Buildup

Mineral deposits can accumulate in your water heater and throughout your plumbing system as a result of normal use. In particular, if your water supply is “hard,” meaning it has a significant concentration of minerals, you should avoid using it. When this occurs, water transports minerals such as magnesium, calcium, and other minerals with it wherever it travels. Your water heater, pipes, water filter, and other components of your home’s plumbing system are included in this category. It is possible for minerals to accumulate in such a thick layer that they begin to obstruct water flow through your system, diminish the amount of water pressure, and prevent your water heater from functioning correctly.

It’s also necessary to descale them at least once a year to ensure that they continue to function at their peak for as long as feasible after installation. You may be experiencing hard water if you find yourself descaling your water heater more than once a year.

Too Many Hot Water Fixtures Being Used at Once

The usage of too many hot water fixtures at the same time in your household might give the impression that your tankless water heater is not heating adequately, which can be misleading. For example, if you and a houseguest attempt to take hot showers at the same time as your child is attempting to wash dishes, your water heater may get overloaded. When your shower begins off hot, but then the cold water starts running for a long before the hot water returns, you have an issue similar to this.

  1. There may still be some hot water remaining in the pipes, but it is unlikely that there will be enough water to take a complete shower with.
  2. If this is only happening once or twice a week, you might try using fewer appliances at the same time to see if this resolves the situation.
  3. Suppose the water heater shut down due to a high level of demand on the system If this is the case, then resetting the device should resolve the situation.
  4. As a result, you may want to consider purchasing an extra water heater or replacing your present water heater with a one that has more storage capacity.

The Air Supply or Exhaust Is Blocked

It is possible that your exhaust or air supply can become clogged, resulting in your tankless water heater ceasing to function properly. Many water heaters will automatically switch down in order to safeguard the appliance and to assist prevent potential safety dangers that might occur as a result of the malfunction. One of the possible causes of this problem is that a vent pipe has been disconnected or has a hole in it. The same thing might happen if your water heater is put too close to another appliance or other object.

For example, an animal or pest such as a wasp might have infiltrated the system’s area by constructing a nest or other barrier that is now obstructing the system’s air supply or exhaust venting.

Failed Ignition

It is also conceivable that a breakdown of the ignition system is the cause of your lack of hot water in your home. If your water heater displays an error message, this is a solid sign that you may be experiencing an ignition problem. This most frequently occurs when there is a problem with the supply, such as when the propane tank is running low or when the water or gas valves are not open properly. However, an ignition failure can also be a symptom of a more difficult or hazardous problem, such as an electrical hazard, which should be addressed immediately.

As a result, if you receive an error notice, it is essential to call a plumbing specialist immediately. They can assist you in determining what is wrong and can safeguard your family by resolving the problem as promptly and securely as possible.

Flame Failure

In a similar vein, problems with your water heater’s fundamental supply can also cause the flame to fail. But if you are not experiencing a problem with the supply, then a variety of other issues, such as troubles with your gas line, electrical wiring, or venting, might be the root of your problem. Fortunately, if you have a problem with your tankless water heater, it does not have to be catastrophic. Contacting a plumbing specialist as soon as you spot a problem allows them to get to the source of the problem and do the necessary water heater repairs quickly and efficiently.

How to Descale a Tankless Water Heater

A qualified plumber is typically the best choice when it comes to descaling a tankless water heater because they are more knowledgeable. Professionals with appropriate knowledge and equipment can remove sediment accumulation from your hot water heater with ease. Moreover, they understand how to keep it in peak operating condition for the longest period of time. If, on the other hand, you decide to flush it on your own, it is prudent to follow a few crucial measures. First and foremost, it is critical to inspect your water heater on a regular basis for mineral buildup and debris that might be preventing the system from functioning as efficiently as it should.

  • However, a multitude of reasons might contribute to the requirement for more frequent cleaning.
  • In this instance, your water heater may require flushing on a more frequent basis than once a year.
  • Following that, it is beneficial to obtain all of the necessary tools before attempting to begin a descaling process.
  • However, you may also purchase each item separately.

Steps to Descale a Tankless Water Heater

  • Turn off any electrical power, gas, or water that is running to the water heater to prevent damage. In most cases, depending on whether you have a gas or electric unit, this comprises actions such as disconnecting the unit’s electric power source or closing the unit’s gas isolation valve. Check to see that the water heater’s circuit has been turned off and that the water shut-off valves have been closed. Then, by opening the hot water pressure relief valve, you may relieve pressure in the entire system. Then, connect the hot water and cold water hoses to the service ports on the water heater. After you’ve connected everything, put the pump from your flush kit in your bucket to start the process. Connect the hose from the cold water port to the pump and insert the other end of the hot water line inside the bucket to complete the installation process. After that, fill the bucket halfway with a cleaning solution designed for water heaters. Following the completion of the system preparation, open both of the service ports and switch on your pump. Allow at least one hour for the pump to operate. This will circulate the cleaning solution through your tankless water heater, flushing out any sediment that may have accumulated in the system. Turn off the pump when it has done descaling your system, throw out the cleaning solution, and drain any cleaning fluid that may have remained in the system. Finally, restore your system by performing the steps outlined above in the reverse sequence of execution. Removal of the hoses from the service ports, reopening of your valves, reactivation of the water heater, and reconnection of the unit’s water, gas, and electrical supplies are all required.

How to Reset Tankless Water Heater

Resetting a tankless water heater is frequently one of the most straightforward methods of getting a heater back up and running. In certain cases, restarting your heater may be as simple as hitting the electric reset button on the control panel. If the reset switch on another model has been tripped, you may need to take further steps to restore functionality. In this situation, the best course of action is to contact a certified plumber for assistance. A plumber can take care of any water heater repairs that are required.

ABC Can Fix and Maintain Your Tankless Water Heater

When it comes to dealing with a water heater problem, it’s best to leave it to the professionals to handle.

If you are experiencing problems with your tankless water heater, call ABC HomeCommercial Services. We will be able to diagnose and repair your water heater in a timely manner. Our continuing maintenance service includes cleaning your water heater as well as notifying you of any possible concerns.

6 Common Tankless Water Heater Problems and How to Solve Them

Tankless water heaters are a terrific investment for your home or workplace since they are energy efficient. Because they heat water just when it is needed, they are not only incredibly efficient, but they may also save you money. Despite the fact that it is rare, problems might develop if anything in your water heater is not functioning properly. Tankless water heaters are susceptible to a number of difficulties and maintenance issues, which are listed below:

  • Mineral buildup, system overload, cold water sandwich, air supply or exhaust blockage, ignition failure, and flame failure are all possible causes of failure.

Continue reading to understand what indications to look for when recognizing these difficulties, as well as how to resolve them!

Problem 1: Mineral Buildup

To find out what to look for when recognizing these problems and how to resolve them, continue reading.

Troubleshooting The Most Common Tankless Water Heater Problems

Tankless Water Heater Troubleshooting: The Most Frequently Asked Questions The Most Frequently Asked Questions About Tankless Water Heaters Purchasing a tankless water heater for your workplace or house is a fantastic investment. Not only are they extremely energy efficient, but they may also save you money by only heating water when it is needed. Even if the situation is unusual, worries might arise if something isn’t operating properly with your water heater.

  • Mineral Accumulation, System Overload, Cold Water Sandwich, Air Supply or Exhaust Blockage, Ignition Failure, and Flame Failure are all possible causes of failure.

Find out what symptoms to watch for and how to address these issues by reading the following! Mineral Accumulation in a Tankless Water Heating System Regardless of whether you have a traditional or a tankless hot water heater, you will need to keep an eye out for mineral buildup inside your water heater over time. Hard water (as opposed to soft water) is water that contains a high concentration of mineral material, and the harder your water, the greater the likelihood of harmful mineral buildup.

  1. The water filter in your hot water heater should be checked periodically if you own or are upgrading from a traditional storage-tank water heater to a tankless one.
  2. Tank water heaters may not require cleaning as frequently, if at all, as tankless hot water heaters, however tankless hot water heaters do require additional maintenance to ensure a long service life.
  3. If you are only checking your water filter on a regular basis, particles might become caught in this long route if you do not visit your water filter often.
  4. You may also use a water softener to help delay the accumulation of scale and other contaminants.
  5. Depending on the capacity of your tankless hot water heater, having too many users at the same time (for example, many showers running at the same time) will overload your hot water heater.
  6. If this occurs, you will need to lower the demand for warm water by minimizing the number of synchronized usages, and you may want to consider resetting your system if necessary.
  7. The installation of a second system may seem like a significant financial commitment, but it may really save you money in the long term since you’ll use less water while waiting for warm water to arrive and less gas to heat the water in the meanwhile.
See also:  How To Shut Off Water To Hot Water Heater

Sandwiches made with iced water If you and your family take back-to-back showers on a frequent basis, you may notice something called a “cold water sandwich.” So, someone in your household has just completed bathing and it’s your turn to do the same.

However, the water is immediately turned cold and continues to be used for many seconds until the temperature gradually increases again.

During the first few minutes of the second shower, the warm water that you felt was really trapped water.

Your shower may be running chilly owing to cold water accumulating in the pipes connecting your water heater and your shower.

This cannot be prevented, but now that you are aware of the situation, you may refrain from leaping in the shower until after the cold water has passed.

This indicates that your water heater is experiencing problems with either the combustion air or the venting.

Consult your product handbook to ensure that the clearance requirements are satisfied before installing your water heater.

Birds’ nests, rats’ nests, and wasps’ nests can all obstruct your venting, so be sure to properly inspect all vents that are located or lead outside your property before closing them.

There are a variety of reasons why your hot water heater might not be able to ignite.

If your gas valve or water valves are not completely opened, this might also result in the ignition not operating properly, as described above.

If following these methods does not address the ignition problem, it is possible that your ignition pack has failed or that there is a more serious issue.

There will be no flameage.

When it comes to ignition failure, you should first rule out simple explanations such as a low gas tank or a cut off caused by an unpaid gas payment that is past due.

Other potential causes of flame failure include a gas line that is too narrow, a faulty regulator, combustion issues, improper venting, and others.

Having a Tankless Water Heater Issue, However Unsure the Precise Problem?

Tankless water heaters are often low-maintenance and extremely effective, but they are not without their flaws. This list highlights some of the more common concerns that people have while using tankless hot water heaters, but it is not exhaustive in nature. South End Plumbing specialists in tankless water heaters, so keep in mind that we are only a click away if you need help. We also specialize in leak detection; please contact us for more information. South End Plumbing is one of the few organizations that will provide you with a no-obligation quote.

Troubleshooting Tankless Water Heater Problems

Learn about typical tankless water heater problems, including their origins, symptoms, and troubleshooting techniques. Learn how to fix a tankless heater when there is no hot water, when the water is excessively hot, or when there is not enough hot water to go around. You’ll learn how to fix a water heater when the pressure is low, how to avoid cold water sandwich (when water temperature fluctuations: hot-cold-hot), why the gas burner won’t ignite, and what to do if there is an error code shown on the water heater display.

  1. Whether you have a Rinnai, Noritz, Palama, Bosch, Takagior similar tankless water heater, this troubleshooting information will be of use to you.
  2. It is not necessary to do any maintenance on a tankless water heater because they are resilient and long-lasting appliances.
  3. I’ve noticed that one of the most common complaints I’ve read in numerous reviews and forums is that “I didn’t get hot water right away.” Alternatively, it takes an excessive amount of time for hot water to reach the fixture.
  4. It is important to understand this.
  5. If this is what you require, you should purchaseRinnai RUR98 or Navien.
  6. A result of the lengthy water pipes, cold water that has collected within must be pushed away before hot water can reach the fixture, reducing the level of convenience.

Common tankless water heater problems

Some of the most common tankless water heater difficulties include: “Hot water is not provided instantaneously,” as well as the following:

  • No hot water (which is frequently caused by a failure of the flame and/or an absence of ignition)
  • Water is too hot
  • Water is not hot enough
  • Water is too hot or not hot enough The burner does not come to life. The burner is excessively loud
  • Water pressure is inadequate. The temperature of either the cold water sandwich or the hot water swings. Testing for the presence of a plumbing crossover

a lack of hot water (which is frequently caused by a lack of ignition or a failure of the flame) When the water is either too hot or not hot enough, the result is the same. A problem with the burner’s ignition. Moreover, the burner is very loud. Water pressure is low. The temperature of a cold water sandwich or hot water changes. A plumbing crossover is being tested.

Fixing tankless water heater problems

  • One of the most prevalent difficulties with water heating systems is that there is no hot water. The first thing you should verify is that the water heater is receiving an adequate amount of energy, water, and natural gas. Check to see that the shut-off valve is not completely closed. Check the gas burner to see whether it is working properly and whether the flame rod is generating sparks when the device is switched on. You may learn more about the subject of ignition failure by reading this article. Determine whether an error code appears on the unit’s control panel, which prevents the heater from being used until the preceding issue has been resolved and the system has been reset. Is the bare minimum of water flow attained here? Check to see that the tap is open wide enough to allow for the desired flow rate and that there are no obstacles in the piping line
  • Observe whether the components and water pipes are exposed to freezing temperatures or if they are maybe completely frozen. Make certain to insulate all of the exposed pipes, including the heater, by wrapping it in an insulating jacket.

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Water is too hot

  • The thermostat is set at an excessively high temperature. Reducing the temperature will help to prevent scorching hot water, energy waste, and excessive operational expenses. If the water flow is decreased as a consequence of blockages in the water filter or plumbing, only a limited volume of water will be heated, resulting in temperatures that are greater than normal in some cases. Clear the water channels of debris. The showerhead or hot water tap should be checked for obstructions, since this will restrict the flow of water. Fixtures should be cleaned. If there is a buildup of sediment, it is necessary to flush and descal the system. Learn how to do that by reading this tutorial. Try to either re-position the temperature sensor to ensure that it is securely attached to the pipe or replace the sensor with a new one if the sensor is damaged or not appropriately positioned. Check the output temperature sensor to see if it is damaged
  • It may be. If necessary, it should be replaced.

Water is not hot enough

  • The temperature of the water is set too low. Raise the temperature to roughly 125-130 degrees Fahrenheit, or higher if necessary
  • When the water filter or fixture aerator becomes blocked, the flow of water may be decreased as a result. If there is a plumbing crossover, cold water is mixing with hot water, resulting in a reduction in the temperature of the incoming water. It is possible that the single-lever mixing valve was installed and failed, which would necessitate the need for the plumbing crossover. It is either because the gas pressure is too low or because the valve is not fully open that the pressure provided by the gas valve is insufficient. Is the gas line of the appropriate size? Obtain an inspection from a qualified gas technician to determine whether the gas supply or components are malfunctioning. Inside the heat exchanger, sediment and limescale have accumulated. It is possible that you will wish to proceed with the descaling and flush out all the sediments. The scale deposits function as an insulator, preventing the heat exchanger from effectively transporting the heat to the water it contains. Is the venting system free of debris, and does it deliver enough fresh air to allow for proper combustion to take place?
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Gas burner does not ignite, and no flame is present

  • Check to see that the electricity, gas, and water are all switched on and that the water is provided to the tankless unit without interruption. Check to see that the gas type and pressure are correct, as well as that the gas line is the proper size. Ensure that the gas line is completely free of air. Check to see that the flame rod and wire harness are in good working order, that they are not loose, that they are in the proper location, or that they are not damaged. Is there any opening of the gas control valve, or is there a short circuit
  • And Is the vent system properly installed and is the length of the vent system appropriate? Do you think there’s a lot of moisture that makes it difficult to differentiate the flame? Is the flow rate higher than the minimum recommended? Check to see that the flow sensor is functioning properly.

The unit is too noisy

  • Check for debris in the fan’s blades. Inspect to see if the gas is being burned by the burner with a clean, bright blue flame. When there is a leak in the sealed combustion, the gas combustion becomes erratic. Stable burner flames that are unstable owing to incorrect venting, a shortage of combustion air, and a high gas pressure

Low water pressure

  • Examine whether or not the water pressure provided by the utility provider is adequate
  • Examine the plumbing, fixtures, and water filter to make sure there are no clogs. As a result of the increased water consumption and the simultaneous operation of several applications, As a result of decreasing gas pressure, the water heater will reduce the amount of water it uses to achieve the desired output temperature.

Cold water sandwich or hot water temperature fluctuates

The term “cold water sandwich” refers to when you turn on the shower and get warm water at first, followed by a blast of frigid water, followed by warm water again. If you utilized the water heater prior to taking a shower, some hot water was left over from earlier usage, which is why you felt the hot water. Although the trapped water has been released, the heater has not been able to heat the water as quickly as it should have, leaving you exposed to chilly water. The longer the pipes, the further the water must flow, and the greater the sensation of a chasm you will experience.

  • A fluctuation in the plumbing system’s performance Check to see that the gas line is the proper size and is capable of carrying the maximum BTU. It is important to ensure that there is no plumbing crossing when mixing cold and hot water. Ensure that the length of the venting pipe does not exceed the specified restrictions. It is possible that a flow sensor has been damaged. The water filter on the cold water input is clean and free of dirt, so check it.

Please keep in mind that if the temperature of the hot water changes throughout the shower, it is advised that you combine your tankless with a tiny tank that acts as a “buffer.” The tiny tank will always have hot water available and will transport it to the shower before the tankless system has had a chance to warm itself up.

How to test for the plumbing crossover problem

  • Turn off the cold water supply to the water heater. Turn on all of the hot water faucets. It is possible that the crossover is malfunctioning if there is still a flow of water after around 10 minutes or so.

Error codes

Tankless water heaters are often outfitted with an on-board diagnostic system that contains a microprocessor and an LCD screen, which displays an error code in the event that a problem arises. The occurrence of an error code can be caused by a variety of factors ranging from a simple spider web and air/exhaust obstruction to a more significant gas or exhaust leak. Use the following articles to learn how to troubleshoot problems on Rinnai, AO Smith, Noritz, and American water heaters and boilers.

See also:  How To Remove Heating Element From Water Heater

During this period, the fan motor continues to spin for a period of time in order to drive the exhaust gases to exit through the vent system.

For example, when taking a shower, the water became chilly because the flow rate from the faucet was lower than the minimum.

In addition to the white smoke that comes out of the exhaust vent, which can be seen during cold weather when the temperature of the exhaust gases is significantly higher than that of the surrounding air, another “unusual activity” is the appearance of a white cloud of smoke coming from the exhaust vent.

Some issues may only be resolved with the proper tools and knowledge, therefore it is in your best interest to consult a professional plumber to ensure that your warranty remains valid and that your unit continues to perform properly.


Many of the advantages of tankless water heaters, as well as the reasons for purchasing one, have undoubtedly already been discussed with you in some form. Things like saving a considerable amount of money on your energy bill, contributing to the environment, and never running out of hot water when you need it are all possible. But what happens when things don’t turn out the way you expect them to? Tankless water heaters are clearly becoming more popular, but they aren’t without their flaws–or, at the very least, they aren’t invincible.

The following are the seven most frequent tankless water heater issues:

  1. There is no ignition message. Building up of mineral deposits
  2. Receiving a flame failure notice
  3. The hot-cold-hot conundrum
  4. Overloading the system
  5. Air supply/exhaust obstructions
  6. And insufficient flow rates are all possibilities.

See if we can figure out what went wrong and how to repair it.

My tankless water heater won’t ignite

Ignition troubles are a pain in the neck. Depending on your tankless water heater’s model, it should display a warning that says something along the lines of “no ignition.” There are a variety of reasons why this could occur. Naturally, before proceeding further, you’ll want to be certain that your gas supply hasn’t just run out. To do this, check the following: Check to see that your propane tank is fully charged. Similarly, if your gas or water valves are not fully opened, your ignition may not work properly.

The Solution

Check your propane tank, gas and water valves to see whether your ignition pack has failed after you’ve checked everything else (or there might even be some bigger problem lurking behind the scenes). In most circumstances, the first three stages of testing for an ignition problem will reveal the problem; if you’re still stuck after that, it will be required to contact technical support or a plumber to discuss the problem and maybe purchase new components.

My tankless water heater is growing something…

The majority of the time, this is nothing we can’t fix: a calcium and magnesium combination that has accumulated in your tankless unit, causing a scaly buildup. I’m sorry, but I’m afraid I won’t be able to assist you if something else is developing in your tankless water heater. But, in all seriousness, mineral buildup is something that should be monitored. Water heating systems will be subjected to enormous volumes of water on a daily basis under all circumstances. This can range from soft to hard water (or everywhere in between) depending on your location and local water supply; while ‘hard water’ refers to water sources that are heavy in minerals and tend to feel a little harsher on your skin.

Mineral build-up can impede the operation of your tankless unit by clogging the valves or by causing the components to fail to work properly.

The Solution

It’s a combination of calcium and magnesium that generates a scaly buildup in your tankless unit, and 99 percent of the time it’s nothing we can’t fix: Sorry, but I’m afraid I won’t be able to help you if something else is developing in your tankless water heater. On the other hand, mineral build-up is something to be cautious about. On a daily basis, all water heating systems will be subjected to enormous levels of moisture. This can range from soft to hard water (or everything in between) depending on your location and local water supply; while ‘hard water’ refers to water sources that are heavy in minerals and tend to feel a little harsher on your skin.

More mineral build-up in your tankless water unit is more likely to occur in hard water, which increases the likelihood of this happening. Mineral build-up can impede the operation of your tankless unit by clogging the valves or by causing the components to fail to work correctly.

Flame Failure message

This is quite similar to your situation with the ignition not working. Among the other factors that contribute to flame failure problems include inadequate ventilation, a gas line that is too short or small to maintain a steady flame, and regulator failures.

The Solution

Remember to go through the fundamentals one again before calling help. Inspect the condition of your propane tank (and make sure you have paid your gas payment this month!). Otherwise, check to make sure that the venting in your tankless unit hasn’t been obstructed or shut down completely (which can kill the flame). If none of these measures prove successful, it may be necessary to seek professional assistance.

My shower goes from hot to cold to hot again

In family settings, this is particularly prevalent; perhaps you’ve observed that it seems to happen when you shower immediately after another family member or spouse? There is a straightforward explanation for this, and it is a significant drawback in many tankless water heating equipment. For those of you who are unfamiliar with the term “cold water sandwich,” it is referred to as such in the water heater industry. Consider the following scenario: a family member has just finished in the shower, and you have just gotten out of bed.

What’s going on here?

It’s actually rather straightforward, to be honest. It is necessary for the person who showers first to allow for some initial waiting time as the water in the unit heats up. When the system is up and running, they will shower to their hearts’ content and then switch off the shower while the hot water is still pouring in their faces. This leaves some hot water in your heating unit that may be used later. In this case, when you arrive and turn on the shower, you will be greeted with the leftover hot water; but, if the unit has been turned off, the heating process will have to be restarted.

The Solution

However, while tankless water heaters heat water significantly more quickly than traditional tank versions, they are not truly instantaneous in their heating. Although I’m sorry to disappoint you, the six to seven seconds of cold water is not a problem; it is just a function of the system, and there is no way to “repair” it at this time. Waiting for the initial surge of warm water and cold water to pass by before jumping into the shower (unless you prefer a quick blast of chilly water!) is the best answer.

My tankless water heater shuts down when too many taps are running

This is referred to as a system overload in some circles. Every tankless water heater will have a maximum capacity; if the load surpasses this limit, the tankless water heater may not be able to keep up. For example, running numerous showers at the same time, utilizing hot water from the kitchen tap while taking a bath in the other room, or even just running two taps at the same time, might cause your unit to go into overdrive.

It might be anything from your heating unit completely shutting down to simply not being able to create enough hot water to supply all of the essential outlets in your house.

The Solution

Depending on the severity of the problem, you may be able to resolve it by either:

  1. Reduce the number of showers, taps, and water outlets that may be used at the same time
  2. Increase the capacity of your tankless water heater
  3. Or purchase a second heating unit.

If you are only experiencing this issue on rare times, the first option will be sufficient to resolve the problem on its own. To avoid this, simply be mindful of running more than one shower at the same time, and be sure to notify your spouse if you’re running hot water in the kitchen while they’re showering! If the situation is more serious, you may be able to cover the load by improving your existing equipment. Modern tankless water heaters are capable of providing ready-hot water for a whole family, which is a significant improvement over previous models.

Even while this appears to be a bit extreme (I thought the goal of tankless water heaters was to save both time and money), if you follow the argument through, you’ll discover that it is still worth your time and effort.

By installing a second unit, you will only use it when it is necessary–it is not a recurring expense, but rather a one-time investment that will save you money in the long term.

My tankless water heater’s air supply or exhaust is blocked

You may have gotten a notification on your unit informing you that the air supply has been interrupted–this message may not have been very helpful to you, however! Whenever an error code is shown, the machine is informing you that there is an issue with the combustion air or the ventilation system.

The Solution

The first step is to look around for any visible threats or objects that may be obstructing your vents before proceeding. This may be something from your own home (for example, a piece of laundry that made its way into the back of the unit) or something from another country, such as a wasps’ or a rodent’s nest. I understand how you feel. Check your vent pipes next; make sure they are not damaged or dislodged, that they are correctly attached to the unit, and that they are not punctured or otherwise compromised by anything.

The final step is to make sure that everything has been installed correctly by consulting the product documentation.

The hot water shuts off in the middle of my shower

If you’ve ever had a problem with your tankless water heater, I understand your dissatisfaction with it. It’s a jarring experience to hear your heater turn off in the middle of a shower and then feel the blast of cold water hit you. Specifically, older tankless water heater models–designs that were created 10 or more years ago–are especially susceptible to this problem. It has something to do with the fact that your water heater’s minimum flow rate is set too high. It is important to understand that minimum flow rates indicate how much water must pass through your tankless water heater in order for it to truly operate; that is, in order for it to get the “heating signal.” Having an old-school tankless unit paired with a recently installed, environmentally friendly showerhead is the most likely scenario in which this problem may emerge.

Tankless water heaters shut down automatically when there isn’t enough water flowing through the device as a safety measure.

There is a significant risk of overheating if there is not enough cold water flowing through the unit–which is why manufacturers often include this safety feature. It’s great for keeping the home from burning down, but it’s not so great when you’re just trying to warm up in the shower.

The Solution

There are two approaches to taking on this challenge, but unfortunately (in contrast to some of the other issues on this list), there is no straightforward answer to it. The first step is to replace your showerhead with one that produces a greater amount of water flow than the one you now have. Of course, in doing so, you would be defeating the point of having installed an environmentally friendly shower head in the first place. I propose this remedy in case your showerhead isn’t especially environmentally friendly, but it’s just ineffective.

The second route necessitates the use of a specialist.

Older units generally had a minimum flow rate of 12 to 34 gallons per minute (gpm), however current designs enable you to go as low as 14 gpm for the smallest unit.

Summing Up

Many of the most prevalent issues can be avoided if they are caught in their early stages. Preventing things like mineral buildup can be accomplished with regular maintenance, and other typical problems may be resolved without the need for a plumber’s assistance. Do not be concerned if you come to a snag on your journey. Discourse with a support team and attempt to locate the particular tankless water heater problem with their assistance–it will be much less expensive to identify the precise problem and replace the problematic item than it will be to contact a plumber or repair business.

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