Is your tankless water heater shutting off unexpectedly? Having hot water trouble in your home can be extremely frustrating. If your tankless unit keeps shutting down, don’t panic. In this comprehensive guide, we’ll walk through the top reasons a tankless heater shuts off and what to do about it.
If you’re short on time, here’s a quick answer: The most common reasons a tankless water heater shuts off are sediment buildup in the heat exchanger, insufficient gas flow, failed thermal sensors, or faulty electronics.
Fixing the issue requires flushing heat exchanger coils, adjusting gas pressure, replacing sensors, or resetting control boards.
Sediment Buildup in Heat Exchanger
One of the common reasons why a tankless water heater keeps shutting off is sediment buildup in the heat exchanger. This can occur over time, especially in areas with hard water. Hard water contains high levels of minerals such as calcium and magnesium, which can accumulate inside the heat exchanger and form a layer of scale.
Hard Water Leads to Scale Buildup
When hard water flows through the tankless water heater, the minerals in the water can deposit on the heat exchanger. Over time, this scale buildup can restrict the flow of water and disrupt the heating process. As a result, the water heater may shut off to prevent further damage or overheating.
According to a study conducted by the Water Quality Association, approximately 85% of homes in the United States have hard water. This means that many homeowners are at risk of experiencing sediment buildup in their tankless water heaters.
Flushing the Heat Exchanger
To address sediment buildup in the heat exchanger, it is important to regularly flush the system. Flushing involves removing the accumulated scale and debris from the heat exchanger to restore its efficiency. This can be done by following the manufacturer’s instructions or seeking professional help.
It is recommended to flush the heat exchanger at least once a year. Regular maintenance not only helps prevent shutdowns but also extends the lifespan of the tankless water heater.
Water Softener Prevents Scale
Installing a water softener can be an effective solution to prevent scale buildup in the heat exchanger. A water softener treats the incoming water by removing the minerals that cause hardness. By reducing the mineral content, a water softener helps minimize scale formation and prolongs the life of the tankless water heater.
The Water Quality Association suggests that a water softener can reduce energy consumption by up to 29% in a tankless water heater. This not only saves money on energy bills but also decreases the likelihood of shutdowns due to sediment buildup.
Insufficient Gas Flow to Burners
One possible reason why your tankless water heater keeps shutting off is due to insufficient gas flow to the burners. This can cause the heater to not produce enough hot water or to shut down completely. There are several factors that can contribute to this issue.
Check Gas Line Sizing
The first thing you should check is the sizing of your gas line. If the gas line is too small or not properly sized for your tankless water heater, it may not be able to deliver enough gas to the burners. This can result in inconsistent heating or frequent shutdowns.
You can consult a professional plumber to evaluate the gas line sizing and make any necessary adjustments.
Confirm Adequate Gas Pressure
Another factor to consider is the gas pressure. If the gas pressure is too low, it can cause the burners to not ignite properly or to shut off prematurely. You can use a gas pressure gauge to measure the gas pressure at the inlet of the water heater.
The recommended gas pressure for most tankless water heaters is typically around 3.5 to 7 inches of water column. If the pressure is significantly lower than this, you may need to contact your gas provider to address the issue.
Clean or Replace Orifice
The orifice is a small component in the burner assembly that controls the flow of gas. Over time, it can become clogged with debris or mineral buildup, restricting the gas flow. Cleaning or replacing the orifice can help restore proper gas flow to the burners.
It is important to refer to the manufacturer’s instructions or consult a professional to ensure proper cleaning or replacement procedures.
By addressing the issue of insufficient gas flow to the burners, you can help prevent your tankless water heater from continuously shutting off and ensure a consistent supply of hot water in your home.
Failed Thermal Sensors
One of the possible reasons why your tankless water heater keeps shutting off is due to failed thermal sensors. These sensors play a crucial role in monitoring the temperature of the water and the overall operation of the heater.
When these sensors malfunction, they can cause the heater to shut off as a safety measure to prevent any potential damage or hazard.
Flame Rod Sensor
The flame rod sensor is responsible for detecting the presence of a flame in the burner assembly. If the sensor fails to detect a flame, it sends a signal to the control board, which then shuts off the gas supply to the burner.
This safety feature is designed to prevent gas leaks and potential fire hazards. If the flame rod sensor is dirty or covered in carbon deposits, it may not work properly and cause the water heater to shut off. Cleaning or replacing the flame rod sensor can help resolve this issue.
High Limit Sensor
The high limit sensor is another important component that can cause your tankless water heater to shut off. It monitors the temperature of the water and shuts off the heater if it reaches an unsafe level. This sensor is designed to prevent overheating and potential damage to the unit.
If the high limit sensor is faulty or incorrectly calibrated, it may shut off the heater prematurely. Replacing the high limit sensor can help rectify this problem and ensure the safe and efficient operation of your water heater.
Replacing Sensors
If you suspect that the thermal sensors in your tankless water heater are causing it to shut off, it is recommended to consult a professional technician. They have the expertise and knowledge to diagnose and replace any faulty sensors effectively.
Attempting to replace the sensors yourself may void the warranty and could potentially lead to further issues or safety hazards. It is always best to leave such tasks to the professionals to ensure the proper functioning of your tankless water heater.
For more information on tankless water heaters and troubleshooting tips, you can visit trustworthy sources such as Energy.gov or Hunker.com.
Faulty Control Board
If your tankless water heater keeps shutting off, one possible culprit is a faulty control board. The control board is responsible for regulating the flow of electricity and ensuring that all the components of the water heater function properly.
When the control board malfunctions, it can cause the heater to shut off unexpectedly.
Resetting the Control Board
In some cases, a simple reset of the control board can solve the problem. To do this, you will need to locate the power supply to the water heater and turn it off. After waiting a few minutes, you can turn the power back on and see if the heater starts working again.
This reset can sometimes clear any temporary issues with the control board and get the heater running smoothly once more.
Control Board Replacement
If resetting the control board doesn’t solve the issue, it may be necessary to replace the faulty control board. This is a more complex task that is best left to a professional technician who has experience working with tankless water heaters.
They will be able to diagnose the problem accurately and install a new control board if needed.
When considering control board replacement, it’s important to weigh the cost of the new part against the age and condition of your water heater. If your heater is relatively new and in good condition, replacing the control board may be a cost-effective solution.
However, if your heater is older and experiencing other issues, it may be more practical to invest in a new water heater altogether.
Remember, if you’re unsure about how to address a faulty control board or any other issues with your tankless water heater, it’s always best to consult with a professional. They can provide expert advice and ensure that your water heater is functioning safely and efficiently.
Conclusion
A tankless water heater that keeps shutting off can be incredibly inconvenient, but the problem is usually fixable. In most cases, shutting off is caused by built-up sediment, insufficient gas flow, bad sensors, or electrical issues.
By identifying the specific cause and making repairs, you can get your hot water flowing again and enjoy the efficiency and convenience of a tankless heater.
