Why Is My Tankless Water Heater Not Getting Hot

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:

In the first place, this is a typical tankless issue known as a “cold water sandwich.” The heat exchanger (the component responsible for heating the water) takes a long time to warm up, which results in this difficulty. You’ll receive a short burst of cold water before it’s totally warmed up and begins heating the water. A constant supply of warm water is then provided after the heat exchanger has reached operating temperature. As a result, where does the first burst of hot water originate from?

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

A variety of various tankless water heater issues might result in you losing access to all of your hot water. In the first instance, regardless of whether you have a gas or an electric tankless unit, it is possible that you are pushing the device beyond its capacity. Given that tankless units only heat water when it is required, running too many hot water appliances at the same time may cause the unit to get overworked and malfunction. It is possible that you may receive hot/lukewarm water in the shower and dishwasher while also trying to wash your hands at the same 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.

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.

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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.

  1. Whenever a hot water tap is switched on, cold water is sent into the unit through a pipe from outside.
  2. Consequently, tankless water heaters are able to provide a continuous supply of hot water.
  3. The output of a tanklesswater heater, on the other hand, is limited in terms of flow rate.
  4. What exactly is the problem when there is no hot water in the house yet there is cold water?
  5. 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?

In most cases, if you’re running the dishwasher while also doing a load of towels and taking a shower all at the same time, you’re pushing your water heater to its limitations. Select the hot water activity that you require at this time, turn off the others, and restart your unit to complete the process. This is frequently caused by running too many faucets at the same time, such as your shower and kitchen sink. Take, for example, the simultaneous use of a shower and a dishwasher, which might cause a tankless water heater to reach its maximum capacity.

Installing separate tankless water heaters for machines that require a lot of hot water in your house, such as a clothes washer or dishwater, is also a viable option.

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.

See also:  How To Ignite Water Heater Pilot Light

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!

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.

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.

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.

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.

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.

Alternatively, it is possible that your tankless water heater is insufficiently large to provide sufficient hot water for your home. 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.

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. Reading the owner’s handbook for your tankless water heater is also recommended, since it should contain specific instructions for your particular model.

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

When it comes to dealing with a water heater issue, it’s best to leave it to the professionals. ABC HomeCommercial Services will assist you if your tankless water heater is not functioning properly. Water heaters are complicated devices that require prompt diagnosis and repair. Our continuing maintenance program includes cleaning your water heater as well as notifying you of any possible issues.

  • Mineral buildup, system overload, cold water sandwich, air supply or exhaust blockage, ignition failure, and flame failure are all possible causes of failure.
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Continue reading to understand what indications to look for when recognizing these difficulties, as well as how to resolve them!

Problem 1: Mineral Buildup

No matter whether you have a regular water heater or a tankless water heater, you should keep an eye out for mineral accumulation inside your water heater. Unlike soft water, hard water contains a high concentration of minerals, and the harder your water, the more likely it is that mineral buildup will occur, which may be harmful to your health. It is most typically calcium and magnesium minerals that generate scaly accumulation, and if you do not solve this issue, it can have a negative impact on the performance of your water heater.

  1. This is especially critical if you use well water.
  2. Well water can produce a more rapid buildup of debris in your tankless water heater, making it more difficult for water to pass down the long, narrow channel to the heat exchanger, resulting in reduced efficiency.
  3. To keep your water heater from being damaged, flush it every six months using the Eccotemp EZ-Flush System Descaler Cleaning Kit.
  4. If you do not have access to the necessary hookups to clean your water heater, you will want a valve bypass kit to aid with the cleaning.
  5. If your water heater becomes overloaded, it may struggle to provide the hot water you require or it may even shut down completely.
  6. You should, however, consider upgrading to a tankless water heater with a bigger capacity, or installing a second unit, if your tankless water heater repeatedly becomes overwhelmed.
  7. Having trouble deciding which product will make the best addition to your home?

A Cold Water Sandwich is the third problem.

When you switch on the shower, you will first feel warm water, but you will then be blasted with cold water for several seconds until the temperature gradually returns to normal.

When the second shower started, the warm water you felt at the beginning 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.

Unfortunately, there is no way to prevent this from happening, but now that you are aware of the issue, you may refrain from hopping in the shower until the cold water has subsided completely.

The display on the majority of tankless water heaters will display an error number to alert you that your air supply or exhaust is obstructed.

The first step is to examine all vent pipes to ensure that they are correctly connected and free of puncture holes.

Installing your water heater too close to other objects might cause an air supply to be blocked, resulting in a fire danger.

Also check any vents that are situated or lead outside your property for nests of birds, mice, or wasps.

The failure of your water heater to ignite might be caused by a variety of factors.

Additionally, if your gas or water valves are not fully opened, this might result in the ignition not working properly.

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.

Problem number six: flame failure.

Just like with ignition failure, you should first rule out simple problems such as a low propane tank or an unpaid gas payment before moving on to more complicated issues.

Contact technical support if you need assistance with troubleshooting the issue any more thoroughly.

Despite the fact that tankless water heaters are typically low-maintenance and highly efficient, issues can occasionally arise.

It does, however, include some of the most typical issues that people have.

We encourage you to contact ourhelp desk to arrange an appointment, or call us at 866-356-1992 if you don’t see the tankless water heater problem you’re experiencing listed below.

In its original form, this article was published by Robinson’s Plumbing Service and was edited by Eccotemp. To locate the ideal hot water solution for all of your requirements, use our Product Selector tool.

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

Some of these issues are simple to resolve, while others are more difficult. If you want assistance, please visit this website, complete the form, and you will receive up to three FREE quotations. Following the links provided below will take you to a list of the error codes that have occurred.

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.
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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.

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.


If you have a tankless water heater, you are probably aware that it will occasionally alternate between hot and cold water. This is due to the fact that tankless heaters are intended to operate without any interruptions when heating water. It is not unusual for tankless heaters to be operating at full capacity one second and at half capacity the next. The concern is that this might potentially reduce the efficiency of your tankless water heater, which could result in an increase in your energy bills!

Cold Water Sandwich

Despite the fact that it is quite unusual, you may encounter a tankless water heater problem known as a cold water sandwich. Your water heater will produce hot water for a few seconds, followed by a blast of cold water (cooler), followed by an abundance of warm water, all at the same time. It almost feels like your tankless water heater shuts off for a split second before starting to heat the water, but this is not the case. This can occur when a fixture is utilized shortly after another fixture has been turned off, as is the case in this example.

If you’re washing your hands, a cold water sandwich isn’t likely to be a major inconvenience. However, it might be inconvenient if you’re taking a chilly shower when you’d prefer hot water. Here’s how to get rid of that bothersome temperature variation in your water supply.

How to Fix It

When it comes to repairing a cold water sandwich, you have two options: building a recirculating system or installing a small tank water heater. In fact, several manufacturers are already offering this buffer tank as an option today. Add a recirculating system–also known as a return loop–to your tankless unit if you don’t want a large amount of hot water all at once. This will eliminate the heat exchanger delay. It’s vital to remember, however, that more energy is spent throughout the procedure.

By adding a small tank water heater to your tankless water heater, you may enhance its capacity and avoid the burst of cold water that occurs during use.

Because it just has a five-gallon storage tank, it is extremely energy efficient in operation.

Wrong Gas Line Size

The majority of tankless water heaters require you to (size) expand your gas line in order to ensure an adequate supply of gas. It’s possible that you’ve previously done this and your water is still flowing hot and cold. If so, your line is the incorrect size. It may be necessary to upgrade your gas meter in order to guarantee that your water heater receives enough fuel.

How to Fix It

The majority of tankless water heaters require you to (size) expand your gas line in order to ensure an adequate supply of natural gas is available. Even if you’ve done everything else and it’s still running hot and cold, your line is probably the wrong size for your machine. It may be necessary to upgrade your gas meter in order to guarantee that your water heater receives adequate fuel supply.

Improper Plumbing System Crossover

Tankless water heaters require a direct connection to the supply and return lines in order to function properly. It is possible for cold water to infiltrate into the hot water line when the plumbing was done incorrectly or when a pressure balancing shower valve has to be repaired. This results in the hot water becoming tepid. The hot and cold water will come in bursts until the line heats up after a period of consistent use. It might be tough to diagnose this problem on your own, without the assistance of a trained professional plumber.

How to Fix It

When it comes to repairing a plumbing system crossover that isn’t working properly, you have two alternatives. You have two options for adjusting the temperature of your tankless water heater: increase the thermostat or add a pressure balancing valve. If you choose to raise the thermostat, you will be forced to utilize hot water from every faucet on a continuous basis. Slowly raising the temperature of your hot water supply will allow it to heat up in your return line, which will benefit you.

It will also balance out any extra pressure that occurs when cold water enters the system, preventing you from experiencing bursts of hot and cold water at the same time.

Broken Flow Sensor

Fixing a plumbing system crossover that isn’t working properly is a two-part process. If you have a tankless water heater, you may either adjust the temperature setting on the unit or add a pressure balancing valve. Increasing the thermostat will result in the persistent usage of hot water at every faucet if you do not turn it back down. When you do this, the temperature of your hot water supply will gradually rise, allowing it to warm up in your return line as well. You may check the temperature of your home’s incoming gas line by installing a pressure-balancing valve in your gas line, if you so want.

How to Fix It

It is necessary to determine the cause of the injury. Gas pressure, thermostat, and the water heater component of your system should all be checked for problems. Service Experts HeatingAir Conditioning should repair a failed flow sensor as soon as possible to ensure that your tankless water heater operates as effectively as possible.

Dirty Water Filter

The water filter installed on the cold water input of instantaneous (tankless) water heaters extends the life of the heater and helps it to operate more efficiently by catching (sediments), calcium, lime, and iron in the water. If it becomes too soiled, you may not only experience unexpected spurts of cold and warm water, but your natural gas cost may also spike as a result. If there is an excessive amount of mineral building in your tankless heater, you may need to descale it.

How to Fix It

Replace your system’s filter on a regular basis to ensure that it is operating at peak performance. We recommend that you do this approximately every six months or so.

Corroded Lines

Corroded water lines (in your home) are a typical cause of the sudden bursts of hot and cold water you may encounter. Discolored water and rusty-brown particles in the water are two symptoms that you have a problem with this. Water flowing through the plumbing system of your home has the potential to release internal corrosion, which can then become stuck in the filter of your tankless water heater.

How to Fix It

A plumber from Service Experts HeatingAir Conditioning should be contacted to do an examination. Corroded lines, which can extend beyond tankless systems and produce more significant problems, should be replaced as soon as possible.

Mineral Buildup

Mineral buildup from hard water can have the same effect as a dirty water filter in that it can interfere with the way tankless water heaters produce hot water. It is believed that this sort of accumulation is the most common source of temperature difficulties.

How to Fix It

Calling Service Experts HeatingAir Conditioning for a plumbing examination is the best course of action. We may need to descale your tankless system or install a water softener, depending on the severity of the problem.

In North America, hard water is a typical source of frustration for homeowners. Hard water affects over 90 percent of households in the United States and 85 percent of households in Canada, respectively. A lack of soft water can result in a variety of problems, including:

  • Skin that is dry, dishes that are stained, and clothing that is faded are all symptoms of scale accumulation in pipes and water heaters. In other hot water appliances, such as your dishwasher and clothes dryer, lime deposits can accumulate.

Let the Experts Handle Your Tankless Water Heater Needs

One of the most inconvenient aspects of a tankless system that alternates between hot and cold water is how difficult it can be to figure out why your water heater is acting this way. Your Expertplumber in North Americawill provide expert advise as we explain what has to be done next in your home or business. This includes everything from diagnosing tankless water heater problems to repairing any problems that may arise during our visit. Never let frustration to get the better of you! For more information or to make an appointment, please call 866-397-3787 immediately.

5 Common Issues with Tankless Hot Water Heaters and What to Do About Them

A common source of frustration with a tankless system that alternates between hot and cold water is the difficulty in determining why your water heater is acting in this manner. After explaining what has to be done next, your North American expert plumber will provide professional suggestions. This includes everything from diagnosing tankless water heater problems to repairing any problems that may arise during our visit. Allow yourself to not be overcome by frustration! To arrange an appointment, call us at 866-397-3787 right away!

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