Why Does My Tankless Hot Water Heater Go Cold

Why Is My Tankless Water Heater Running Hot and Cold?

Tankless water heaters provide several advantages over standard storage tanks when it comes to meeting your water heating demands. Read on to learn more. In the case of water heaters, tankless units are more energy efficient than traditional types. This is due to the fact that they do not suffer from standby energy loss in the same manner that a tank model does. The hot water stored in tank water heaters can be utilized immediately, but if the water is not used immediately, the air surrounding the tank might cause the water to cool, resulting in energy waste.

For those considering tankless water heater installation in Pocatello, ID, there are a few considerations to bear in mind before making the decision.

Problems with Tankless Water Heater Temperature

Tankless water heaters provide several advantages over typical storage tanks when it comes to meeting your water heating demands. In comparison to typical water heaters, tankless water heaters are more energy efficient. Due to the fact that they do not experience standby energy loss in the same manner that a tank type does, they are more energy efficient. The hot water stored in tank water heaters can be utilized immediately, but if the water is not used immediately, the air surrounding the tank might cause the water to cool, resulting in wasted energy.

For those considering tankless water heater installation in Pocatello, ID, there are a few considerations to bear in mind before making the leap.

  • A gas pipe that is not the right size, as previously described
  • The presence of a plumbing system crossover in an area where there shouldn’t be one Venting pipes that have been improperly extended
  • It’s possible that your flow sensor has been damaged, and this should be examined at your yearly plumbing maintenance visit. Clean water filter installed on the cold water input
  • Corroded lines—corrosion might develop as a result of humidity pouring onto the gas burner or a heat exchanger that has been improperly fitted.

Finally, mineral accumulation is another issue that consumers frequently see with their tankless systems when they are not properly installed and maintained. It is the buildup of calcium and magnesium that is being discussed. Hard water is the term used to describe this. Hard water may be and often is an issue for pipes, causing hard scale to build up inside them and causing blockages and/or corrosion to occur. A water softener will not only alleviate this problem, but it will also enhance your quality of life by making your showers and baths more refreshing, improving the taste of your drinking water, and even extending the life of your laundry.

If this has already occurred, you will need to hire a professional to clean the lines before you can continue to use your tankless water heater system.

Fend Off Tankless Water Heater Problems with Maintenance

Always plan yearly plumbing maintenance appointments so that our highly skilled and experienced plumbers can thoroughly inspect your tankless water heater, water softener system, and the rest of your plumbing components. In order to avoid the concerns described above that might arise with your tankless water heater, the greatest preventive action you can take is to do regular maintenance on it.

When it comes to offering excellent service, Advanced Home Services is the gold standard. Contact us right now if you want comprehensive plumbing services!

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.

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.

Tankless Water Heater Goes Cold After A Few Minutes

Many customers have expressed dissatisfaction with tankless water heaters since the water becomes cold within a few minutes. That is, in fact, correct, which surprised me. However, there are several unique approaches that may be used to resolve the problem. An electric water heater, which may be either with or without a tank, is a necessary home device that should not be overlooked. Fuel for the water heater can come from either gas or electricity, however the gas type is a more ancient model.

It is used for the comfort of its users.

When hot water suddenly becomes cold after only a few seconds, the user becomes upset.

The Tankless Water Heater Goes Cold After A Few Minutes

A modern tankless water heater ensures that hot water is delivered smoothly. However, as time progresses, it is possible that the water heater will malfunction. One of the issues is that the water from a tankless water heater becomes chilly after a few minutes. In this section, I will discuss some of the reasons why hot water became cold:

Hot Water Become Cold After Lasting a Few Minutes

A dip tube is a tube that connects to the cold water input valve and allows the water to flow through it. Cold water is forced to the bottom of the tank by the deep tube, which is its primary function. Heating elements: The top and lower heating elements of an electric water heater are present. After years of use, these components became corroded and no longer functioned properly to heat water. Thermostat: The thermostat regulates the temperature of the water heater’s heating components. What happens if the thermostat malfunctions?

  1. As a result, the water remains chilly.
  2. It helps to maintain the pressure of the water heater.
  3. Because of the hardness of the water, the heat exchanger system becomes unbalanced.
  4. Ventilation: The water heater employs a ventilation system to keep the water heated while it is still being used.
  5. Burner that is dirty: This burner is used to heat water.
  6. a problem with the availability of fuel: water heaters require fuel (either electricity or natural gas) to operate properly.

However, it is possible that supply will be curtailed for any cause. Incorrectly functioning ignitor: Without an ignitor, it is impossible to imagine heating water in a gas water heater. It might become damaged from time to time.

Preventing Water From Getting Cold

Some issues with your water heater might not need the replacement of the unit. You or a plumber can easily fix them if you know what you’re doing. The following are the solution suggestions: Get yourself a dip tube: It’s possible to become jaded and isolated. It is available for purchase on the market. Replace it with a new one if you want to have hot water. Installation: The consumer places the water heater close to appliances in order to prevent producing pressure. You can utilize a variety of appliances with relative ease.

  • For a brief period of time, you may be able to acquire warm water without electricity.
  • The healing procedure with water gets more difficult.
  • The delivery of fuel continues: The waterheater can be powered by electricity or gas.
  • Temperature controller: As we all know, it is responsible for controlling heating elements, thus it is essential.
  • Instead of replacing the water heater, consider purchasing a new thermostat.
  • When it comes to hard water, a heater problem occurs.
  • It makes room for a water supply valve to be installed.


If your water heater is experiencing some issues, you may not need to replace it right away. Either you or a plumber can swiftly and easily fix them. The following are some suggestions for solution: A dip tube can be obtained from the following sources. Eventually, it becomes stale and lonely. In the market, it is readily available. In order to have hot water, it should be changed. Consumer places the water heater close to appliances in order to prevent producing pressure. Multi-appliance use should be straightforward.

  • For a brief period of time, you may be able to acquire warm water without power.
  • The healing procedure including water gets more difficult to accomplish.
  • Gasoline deliveries are still being made.
  • The supply of their products must be ensured on a consistent basis.
  • It is important not to dismiss the signs that the thermostat is not working.
  • Water softener: It is frequently utilized by customers to handle difficult water-related issues.

With a water softener, you can keep the pipe clean while also improving how good the water tastes! In order for a water supply valve to be installed, it must first clear the way. A water softener is recommended for producing high-quality hot water.


Despite the fact that tankless water heaters become chilly after a few minutes, there is a significant demand for them. Many people choose to use less water heaters as a result of certain simple options, such as storage tanks. People can resolve the problem of cold water and obtain hot water. Every aspect of our daily lives is influenced by this factor. Furthermore, individuals want to employ the most up-to-date technology, such as an electronic tankless water heater. It lasts longer and does not necessitate the use of more room or ventilation.

See also:  How Long Does It Take For Hot Water Heater To Drain?

If you have any questions, please let me know in the comments section below.

Tankless Hot Water Temperature Fluctuates

Tankless water heaters are in high demand, despite the fact that they get cold after a few minutes of use. Due to the availability of several simple options, many consumers prefer to use fewer water heaters. Getting hot water is possible after resolving the cold water issue. Every aspect of our daily lives is influenced by it. As a bonus, modern technology, such as an electronic tankless water heater, is popular with homeowners and business owners. It has a longer shelf life and does not necessitate the use of additional room or air conditioning.

If you have any questions, please let me know in the comments below.

  • Because of the low pressure, the temperature of the hot water fluctuates. Fluctuation caused by a limitation in the flow
  • A fluctuation as a result of the filthy filter screen Fluctuation as a result of the plumbing switchover
  • What is the recommended amount of pressure? The fast temperature fluctuation was caused by a mixing valve, according to the theory. Problem with recirculation

The cold-water sandwich phenomenon

Cold water sandwich, also known as temperature fluctuation, refers to a condition in which supplied water from a tankless water heater is hot during the first few minutes, then changes to cold and then back to warm or hot again. A very uncomfortable environment for users, especially when bathing or showering, is created by this circumstance. Tankless items, particularly those that are driven by electricity, are vulnerable to temperature fluctuations unless the unit is equipped with certain characteristics that can reduce this fluctuation.

After restarting the unit, colder water is forced out of the pipes before hot water can reach the fixture.

What temperature to set

When reading the owner’s handbook for any tankless water heater, it can be seen that the makers recommend that the hot water be kept at a temperature of roughly 120 degrees Fahrenheit to ensure that it is safe. This is the default configuration. The minimum temperature is around 100 degrees Fahrenheit, while the maximum temperature is approximately 140 degrees Fahrenheit for residential usage and 180 degrees Fahrenheit for commercial use.

Low water pressure

One of the most common reasons for temperature fluctuations is when your tankless heater stops operating due to a lack of water pressure in the system. The flow rate within your tankless unit is low, in fact, it is below the activation flow rate, which results in the gas burner being turned off. However, if your heating system includes a standing pilot, just the main gas burner will go off; the pilot light will remain on. Check the instructions to see what the bare minimum flow rate is – it’s generally between 0.4 and 0.5 gallons per minute.

Changing the flow of water in your home will cause a change in the temperature and you will notice a fluctuation or temperature drop if your heating system is not designed properly and your tankless heater capacity is less than demand, as well as if additional fixtures in your home are opened or closed, will cause a change in the flow of water in your home and you will notice a fluctuation or temperature drop.

The ultimate consequence will be an unpleasant shower as well as cold water flowing out of your showerhead as a result of this situation.

Restriction in the hot water flow

Another factor contributing to the fluctuation in water temperature is a limitation in the hot water flow. In order to prevent clogging of plumbing fixtures, faucet aerators, and showerheads caused by mineral deposits, you should inspect them often and clean them as needed. Clean and disinfect each and every one of them, or if they are broken, replace them with new ones. If you want to clean and flush your fixtures, it is recommended that you soak them in vinegar for a few minutes to break down and dissolve mineral deposits, and then flush them with water.

By turning it down to its smallest setting, the water’s temperature will be at its warmest.

Other examples of modulating systems include the RTG-199HE from the Rheem Infinity series, which is equipped with an automatic bypass system that includes the water adjustment valve and a modulating system that ensures excellent temperature stability as well as consistent outlet temperature throughout the draw.

In this article on tankless flushing, the author describes how to completely clean your tankless water heater.

Inlet filter screen

If your tankless unit is equipped with an inlet filter screen, it is possible that it is clogged, preventing water from passing through and causing the flow to be lower than anticipated. The filter may be located in the bottom of the device, and it can simply be removed and cleaned as needed. Replace it if it is absolutely necessary.

Plumbing crossover

When there is an issue with the plumbing, it can also cause an insufficient flow, which is why the tankless water temperature swings, going from hot to cold to hot. Piping crossover is one of them, and it is caused by a bad mixing valve, inappropriate plumbing, or if you have a single-lever faucet with a failing washer. Examine all of the faucets. Close the main valve, turn on the hot water tap, and wait 5 minutes to see whether the water is still running. If it is, you have a plumbing crossover problem.

Water pressure

The water pressure must meet or exceed the manufacturer’s specifications. It is necessary to maintain a consistent pressure of 30 psi even when using other water sources, such as a well, for example.

Mixing valves

Double-check to ensure that the mixing valve is properly placed, since it reduces the temperature of the hot water by mixing it with the cold water. Check the temperature that has been set on the valve. It is recommended that you examine the activation flow rate problem first before making any modifications to your plumbing system or attempting to address the temperature fluctuation problem on your heater.

Calculate the fill time to get the correct activation rate for your system. Generally speaking, if the fill time is longer than typical (even when you are not experiencing temperature variations), the chances of meeting the activation rate are slim.

Problem with a recirculation system

  • Check to see sure the circulation pump is functioning properly. If not, invest in a high-quality replacement, such as thisGrundfos. Make sure there is no air trapped inside the system, since this might interfere with the effective working of the pump. Considering that the smallest amount of flow is necessary, ensure that the pump is not undersized. Check to see that the checking valve is properly placed between the pump output and the connection to the cold water supply
  • And

The following website may be used to engage an expert if you find the above difficulties and activities to be too difficult to complete to resolve the problem with the cold-water-sandwich or the temperature fluctuation. Get Quotes from Highly Qualified Water Heater Professionals! Get Free Estimates on Your Project!

Related articles

  • To hire a professional to handle the problem with the cold-water-sandwich or temperature fluctuation if the above problems and activities appear to be too hard, go to the following website and fill out the form. Water Heater Estimates from the Best in the Business! Estimates are provided at no charge.

Why Does My Tankless Hot Water Heater Go Cold?

To hire a specialist to address the problem with the cold-water-sandwich or temperature fluctuation, utilize this website to find a solution to the difficulties described above. Compare Water Heater Estimates from Highly Qualified Professionals! Request a Free Estimate!

Steps to Take to Avoid Tankless Water Heater Going Cold

If the above difficulties and activities appear to be too hard to fix the problem with the cold-water-sandwich or the temperature fluctuation, you may use this website to hire an expert to assist you. Get Quotes from the Best Water Heater Professionals in the Business! Get a Free Estimate on Your Project!

1. Proper Installation

After purchasing a tankless water heater, the first and most crucial step is to ensure that the device is correctly installed. It is essential that you get expert assistance if your procedure includes gas Piping. This reduces the likelihood of making a mistake that may later cause you discomfort. Make certain that the size of the gas line corresponds to the amount of water that will be used so that the water will heat as needed. Maintain the tightness and appropriateness of all cold water line connections.

If you wish to handle everything yourself, you may ask for assistance from customer support with any questions you might have.

2. Gas Pipe Length

The length of the pipe has an impact on the amount of time it takes for the hot water to be delivered to the faucet. Keep the length of the pipes as short as possible so that cold water can be pushed away more quickly and hot water can reach fixtures more quickly. Consequently, it is usual for all tankless water heaters to require some time before delivering hot water to the fixture in question.

Some Other Common Water Heating Issues Can be

You went to the kitchen to clean dishes one night and all you got out of the kitchen faucet was ice cold water. What happened? If you’re like most people, you’ll be asking what went wrong with the water heating equipment. This occurs as a result of a failure of the flame. The water will not heat up if there is no fire present at all. When it comes to tank-less water heaters, this is a typical problem, and if you experience it, check to make sure that the unit’s water, power, and gas supplies are all working properly and are not leaking or malfunctioning.

Check the control panel of the unit to check if there is any error code that could be preventing the heater from functioning properly. If this is the case, reset the system to get the heater up and running again.

Minimal Flow Rate

Make certain that the flow rate via your tap is acceptable. When the faucet is switched on, the water flow should be adjusted to meet the demands of the water heater in order for the water heating system to function properly. Check to see that the pipes are not obstructed. Low water pressure will have an adverse effect on the operation of the heating unit. It is possible for the temperature to vary if the water pressure is low.

See also:  How To Aerate Water Without Pump?

Frozen Pipes

This problem can arise during the winter months when the water in the pipes freezes, causing it to take longer than usual to obtain the necessary flow of hot water to the faucet. When water hardens inside pipes, heat is first utilized to melt the water and then to heat it, resulting in a water temperature that is higher than predicted when it should be. The time it takes to get hot water to come out of the faucet increases when water is frozen inside the pipes. It is possible to avoid this problem by insulating any exposed pipes.

Water Heater Temperature Setting

What is the optimum temperature for my device to operate at? If you were debating whether or not to answer this question, here is your response. The most common recommendation from manufacturers is to keep the temperature at 120 degrees Fahrenheit, which is the default setting. When used for residential purposes, the lowest temperature restriction is 100 degrees Fahrenheit and the maximum temperature limit is 140 degrees Fahrenheit. Somewhat erroneously, you may have lowered the temperature of your water heater too much.

Water Filter

It is recommended that you clean your water filter once a month to avoid it becoming blocked. If you are unable to obtain hot water out of the tap when you need it, check for the cold water entry into your system and close it. A filter is located at the end of this entrance, which prevents dirt and debris from entering the heating system along with the water it contains. With time, debris can collect and block the filter, causing it to malfunction. This may be avoided by cleaning the filter on a regular basis.

Plumbing Crossover

This condition leads in the mixing of hot and cold water, which results in a drop in the total temperature of the water. In order to keep this from occurring, you must understand how to do a plumbing crossover test. Remove the cold water supply to your water heater and turn it off. Open all of the faucets. If, after approximately 10 minutes of opening the faucet, the water is still gushing out, you have a plumbing crossover problem.

Gas Valve Defect

If the gas valve is not supplying the required gas pressure, the water will not be heated properly. Make certain that the gas connections are completed correctly and with the assistance of a competent specialist. Check for any signs of a suspected leak.

Restricted Hot Water Supply

When the hot water supply is limited, the temperature changes as a result of this. Check the shower heads and fittings to make sure there isn’t anything clogging them. If there is an excessive amount of mineral deposit, the units should be replaced with new ones. It is recommended to clean the fixtures on a regular basis and to soak them in vinegar for a period of time to dissolve the mineral buildup on them.

Several of the most recent tankless water heater models are fitted with an automated bypass system that includes a water adjustment valve. This innovative technology guarantees that the water temperature remains stable and is commensurate with the temperature of the supply water.

Heat Exchanger Sedimentation

When sediments accumulate inside the heat exchanger, the heat transmission is reduced as a result of the reduced heat transfer. Descaling is necessary to remove all of the mineral buildup and to guarantee that the water flowing through the pipes receives the necessary heat supply. Monthly maintenance is essential because it helps to prevent excessive mineral build-up, which, after a period of time, may become irreversible and need the purchase of replacement components.

Coldwater Sandwich

This expression refers to a circumstance in which, when opening the faucet, you do receive hot water, but you also receive an unpleasant torrent of cold water in the meantime. Many people find themselves in this circumstance to be quite uncomfortable. It’s possible that the hot water left over from the previous time you turned on the faucet is to blame. Because the heater was unable to heat the water quickly enough, the owner is forced to use cold water until the water can be heated again. In the absence of any specific measures being implemented in the device to prevent this problem from occurring, this will occur with any tankless water heaters, particularly those that use electricity.

Error Codes

The tankless water heater’s control panel is comprised of two components: an LCD screen and a microcontroller. Whenever a problem occurs, this system shows an error code on the screen. It is possible to decipher the error codes in order to determine the root cause and most likely remedy of the problem. All of the problem codes are stated in the user handbook, and they may also be accessible on the internet. Even obtaining assistance from a professional becomes less difficult since the technician can examine the code and determine the problem.

If you have any questions about “Why does my tankless hot water heater go cold?,” we hope this article was useful in expanding your knowledge.

Please leave a remark below, and we will get back to you as soon as possible.

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I’ve been working in the water heater and plumbing industries for several years. Providing relevant information regarding tankless water heaters is my goal, and I’m here to assist my readers in doing so. Adam’s most recent blog entries (see all)

Feeling stupid, my tankless water heater turns cold when I’m in the shower

I recently had a Navien 240S tankless water heater installed to replace another tankless water heater that rumbled and occasionally shut down. After the installation, I started getting cold water sandwiches over and over again while taking a shower. I’d suggest cold would be a gentle decline from hot to warm to cold so that we can at the very least get out of the shower water, and then it goes back up and remains that way for 2-3 minutes before repeating. After around 20 seconds, the Navien 240S would cut off the flame (at least according to the LCD), then light back up, and this would continue indefinitely.

  • The plumber replaced the 240S with a 240A, and he also checked the dip switches (1 on, 5 on) to see whether the internal pump could be used.
  • As with the 240S, recirculation helps with the first cold water sandwich, but then repeating ones occur, leading us to believe that the problem is not with the tankless, but rather with the system: 1.
  • There are no gas leaks (did the clorox spray – no bubbles, no real smell of gas) 3.
  • 4.
  • 5.
  • 5.
  • Occasionally, even the kitchen sink will suffice.
  • All plumbing past the water input, booster pump, and filter is PEX blue/red lines that appear to be properly connected (black metal bands tightened on joints) – there were no leaks found elsewhere in the house during this inspection.

However, I have visual proof that the flame does switch off (again, the LCD screen of the Navien indicates this) every few minutes for around 20 seconds before re-igniting. I believe that it should be steady at all times. I’m looking for any recommendations you might have.

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

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.

  • This is especially critical if you use well water.
  • 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.
  • To keep your water heater from being damaged, flush it every six months using the Eccotemp EZ-Flush System Descaler Cleaning Kit.
  • 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.
  • If your water heater becomes overloaded, it may struggle to provide the hot water you require or it may even shut down completely.
  • 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.
  • 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.

See also:  How To Get Frigidaire Water Filter Out?

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.

Tankless water heater – one shower got cold

It is the same exact problem that I have experienced with many tankless water systems (3! ), all of which were installed in separate residences at the same time. This is a simple adjustment, and thull from Georgia is correct in his assessment. All you have to do is lower the temperature of your water, because these systems have a built-in safety feature to avoid overheating. This will occur if you use too little water for heating, which is what happens when you shower with a mixture of cold and hot water.


It’s possible that you enjoy a hotter shower than your guests, and as a result, this only happens to them and not you.

They informed me that in this subtropical climate with still four distinct seasons, a temperature of 42 degrees Celsius is sufficient for the majority of hot showers and baths in the winter, and a temperature of 36 degrees Celsius is even hot enough during the hot summer months, when people naturally prefer cooler water and less heat is lost when traveling through the pipelines.

  1. If you want to explore what works for you, you may experiment with your own in your climate.
  2. If the appliance is in a handy location, you can even dial it up for dishwashing and back down for other tasks.
  3. It’s incredibly simple for me because it’s simply a few steps outside the kitchen door.
  4. However, there is one significant difference between the functioning of tankless and tank water heaters that should be explained more explicitly to first-time purchasers.

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? This is the most typical issue that you can anticipate to encounter with a tankless water heating system. 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?

It is energy-efficient, requires little upkeep, and is relatively long-lasting. Tankless water heaters The fact is, they’re not fully impervious to problems, just like any other equipment. They may experience small issues from time to time, such as running out of hot water or the stove not turning on properly. Tankless water heaters, also known as demand-type or instantaneous water heaters, are designed to supply hot water only when it is required. They do not generate the standby energy losses typical with storage water heaters, which can result in significant savings in energy costs.

  1. As soon as the hot water tap is switched on, cold water is sent into the unit through a conduit.
  2. Tankless water heaters, as a result, provide a continuous supply of hot water.
  3. A tankless water heater’s output, on the other hand, has a restriction on how much water can be heated.
  4. If you have a tankless water heater, this is the most likely issue you will encounter.

Am I reaching my minimum flow rate?

Tankless water heaters are energy efficient, need little maintenance, and are relatively long-lasting. However, just like any other equipment, they are not fully immune to malfunctions. They may experience small issues from time to time, such as running out of hot water or the stove not working. Tankless water heaters, also known as demand-type or instantaneous water heaters, deliver hot water only when it is required. They do not cause the standby energy losses typical with storage water heaters, which can result in significant savings in energy costs.

  1. When a hot water tap is switched on, cold water is sent into the unit through a pipe.
  2. Consequently, tankless water heaters provide a continuous supply of hot water.
  3. The output of a tankless water heater, on the other hand, is limited in terms of flow rate.
  4. What exactly is the problem when you don’t have hot water in the house but do have cold water?
  5. You should ask yourself the following questions in order to get to the source of the problem.

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.

  1. It’s the dreaded cold water sandwich, and it’s something that happens all the time in the shower.
  2. Those hot water sensations you’re experiencing at first are due to leftovers from the prior user.
  3. Then, once the heater has completed its task, you will have hot water once more.
  4. 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.
  5. Tankless water heaters are notorious for having this problem.
  6. 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.
  7. 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!

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