Eternal Water Heater Problems

7 Common Eternal Water Heater Problems & Their Solutions

This is a complete troubleshooting guide on the Eternal Water Heater Problem. From this guide, you will learn about the common issues of your water heater & their solutions like:

  • Burner doesn’t ignite
  • Water is not hot enough
  • Water is too hot
  • The water heater makes abnormal sounds
  • And a lot

Plus, we also give you a complete maintenance & service guide so that you can avoid potential water heater issues. It will help you prolong the life of your Eternal water heater. 

So, stay in tune with us till the end to learn how to troubleshoot a tankless water heater like Eternal. 

Table of Contents

Eternal Water Heater Problem: 7 Common Tankless Water Heater Problems & Solutions

How to tell if your eternal tankless water heater is bad? Don’t worry! The following signs will let you learn about a malfunctioning water heater. 

01. Burner Doesn’t Ignite

The burner of your Eternal Tankless Water Heater doesn’t ignite though the hot water is opened. It happens due to the following reasons: 

  • You may not turn the On/Off switch to the On position. 
  • Forget to plug the power cord into a standard outlet
  • The 3A Fuses on the main controller may get blown out
  • You may plumb the cold and hot water lines into the wrong locations
  • Water lines get frosted 
  • Coldwater lines and gas supply lines are close

How To Solve: 

Begin with checking the On/Off switch of your burner is turned to the On position. Also, make sure you plug your water heater into a dedicated electrical outlet. 

Thirdly, ensure the 3A fuse on the main controller is in good condition. If it gets faulty, we recommend you replace it with a new one. Regarding this, call the Eternal Tankless Water Heater tech support team for help. 

Now, it’s time to inspect that you plumb the cold and hot water lines into the right locations. If not, plug both cold and hot water lines into the appropriate ports. 

Next, check the water lines to see whether they get frosted or not. In case of freezing pipes, you can use pipe insulation, a heat gun, or a heating pad to defrost the frozen pipes. To prevent the water lines from freezing, ensure you wrap up the pipes with an electrical heating cable. Then, use pipe insulation to wrap up the pipe and plug the cable into an outlet. 

Lastly, ensure the cold water lines and the gas supply lines are open. 

02. Water Is Not Hot Enough

You plug your Eternal Water Heater into an outlet but still, you don’t get enough hot water. The following culprits are responsible for this issue. 

  • You might set the temperature setting too low
  • The filter in the cold water supply line gets clogged by dirt and debris
  • Incorrect gas supply type
  • Incorrect supply and manifold gas pressures
  • Improper water flow sensor connection with the three wires on top of the heat exchanger

How To Solve:

Firstly, tweak the temperature setting to the high setting. You can set the maximum temperature of the hot outlet by using the controller on the front of the unit. 

If the filter in the cold water supply line gets blocked by dirt & debris, clean the filter. You can hire a certified plumber to do this task for you. On the other hand, if you are mechanically inclined, watch this tutorial to learn how to clean the filter

We recommend you take help from a professional to check the gas supply type and the pressure of the supply and manifold. 

And lastly, insect the wire connection between the water flow sensor and the heat exchanger. If the wire connection is not right, correct it. Alternatively, hire a professional to solve this issue for you. 

03. Water Is Too Hot

The water temperature you get from your water heater will become too hot due to the following reasons:

  • You set the temperature too high
  • Incorrect gas supply type
  • The cold water filter gets blocked by dirt & debris

How To Solve:

First off, adjust the temperature setting by using the controller on the front of your unit. Now, correct the gas supply type. Then, check the cold water filter by releasing the dirt, debris, and dust. The best suggestion is- hire a professional to troubleshoot these issues. 

04. Hot Water Temperature Fluctuates At the Opened Tap

The hot water temperature of your Eternal Water Heater will fluctuate if the filter in the cold water line gets dirty by dirt & dust. Therefore, incorrect gas supply types and insufficient supply gas pressure are also responsible for water temperature fluctuation. 

How To Solve:

Begin with inspecting the filter in the cold water line. If there is dirt or debris inside the filter, clean the filter optimally. We recommend you check the manual to deal with the issue of inadequate supply gas pressure or correct the gas supply type. 

05. Make Abnormal Sounds

Your tankless water heater will produce noise if there is a leak of combustion gas between the sealed chamber and the exhaust tube. Besides, improper venting termination will also make abnormal sounds when operating the heater. Nonetheless, insufficient gas pressure can also be the reason behind an unstable flame & noise. 

How to Solve: 

Run a leak test to find a leak of combustion gas between the sealed chamber and the exhaust tube. If you find any leak, tighten all the points and piping. To fix the venting termination issue, hire a certified expert to install the venting termination properly. Adjust the gas pressure according to the manual to stop abnormal sounds. 

06. Fail to Change The Setting Temperature To Above 140

This is a safety feature of your Eternal Water Heater to prevent scalding. You know that excessively hot water over 125 degrees will cause severe burns or death. Indeed, it’s not a problem actually. 

How to Solve:

As this is not a problem, you don’t need to do anything significant. Just set the temperature setting of the heater according to the manufacturer’s guidelines.  

07. Eternal tankless water heater error codes

Your eternal tankless water heater will show several error codes like E03, E24, and E28. Each of them has different meanings and indicates a specific issue with your water heater. For example, your water heater will display the error code e24 if the mixing valve is not connected properly. 

We recommend you check this article to know more about the error codes and how you clear them.

Maintenance & Service

Before performing any maintenance or service workflows, ensure you turn off the unit and unplug it from the electrical power source. Also, make sure you shut down the gas control valve and the manual water control valve. 

1. Inspect the water heater once a year by a certified technician. If needed, you should replace the parts that get defective or broken. 

2. Verify that you check the following parts once a year:

  • Venting system
  • Burner
  • Operate the pressure relief valve manually to ensure correct operation
  • Clean the water strainer periodically
  • Pull out the thermistor from the unit and inspect for mineral coatings

3. Check the water heater for physical damage. If it has been subject to fire, floor, or others, shut the manual gas shut-off valve. Then, call a certified plumber to check your water heater. 

4. Inspect the temperature setting as hotter water increases the risk of scalding injury. 

5. Check the venting system once a year and verify there is no blockage. 

6. Ensure the flue outlet and the air intake hole on the top of your water heater is clean. If dirt, inspect, and other foreign materials nest on those holes, blow them away using an air compressor. 

7. You should inspect the water strainer annually. It protects the valve from the dirt & pipe scale. 

8. Check the faucet aerators, shower heads, and screens for sediment buildup. 

9. Clean out the condensate trap. 


How To Tell If a Tankless Water Heater Is Bad?

Apart from those tankless water heater problems, the following signs will let you know about a defective water heater.

  • A sudden change in water quality
  • Water smells like rotten eggs
  • Broken heating element
  • Water is leaking from your tankless water heater
  • Sediment buildup

What Happens When A Tankless Water Heater Fails?

A tankless water heater will fail for several reasons- low water pressure, leak in the heat exchanger, and gas ignition problem. When the water heater fails, you will never get hot water from the heater. Therefore, you may get strange tested water. On the other hand, it will be harmful to your house if the heat exchanger gets corroded. 

Why Did My Water Heater Suddenly Stop Working?

Your water heater will stop working suddenly if the fuse of it gets blown out or due to a tripped circuit breaker. Just replace the fuse and plug your unit into a dedicated outlet to let your water heater function properly. 

How Many Years Does A Water Heater Last?

Typically, a water heater will last between 6-13 years if you maintain the heater properly.

What Should It Cost To Replace A Water Heater?

Generally, it costs you between $1150-$3200 to replace a water heater, including the labor and material cost. However, you should count extra $150-$275 if you have a gas operated hot water heater. 


The Eternal tankless water heater is durable, energy-efficient, and requires low maintenance. But it doesn’t mean this heater is completely immune to issues. Tankless water heaters not working, producing no hot water, or broken heating elements are some Eternal water heater problems. 

Fortunately, you don’t need to worry about these issues as we provided the solutions to those heater issues above. Just follow the troubleshooting steps we mentioned and fix the heater problem. Otherwise, you can hire a certified technician to deal with a malfunctioning water heater.

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