How to troubleshoot a tankless water heater

June 24, 2025

How to troubleshoot a tankless water heater 


If you have a tankless water heater and you find that it’s not working, it can be frustrating. However, before you panic and call a professional, there are a few things you can check yourself. Here are some things to look out for if your tankless water heater is not working. 


Check the power source:

 The first thing to check when your tankless water heater is not working is the power source. Make sure the unit is plugged in or that the circuit breaker hasn’t been tripped. If it has, try resetting the breaker and see if that solves the issue. 


Check the gas supply:

 If your tankless water heater runs on gas, make sure the gas supply is turned on and the gas line is connected properly. If the gas supply is on and the unit still isn’t working, you may need to call a professional to check for any gas leaks or other issues. 


Check the water supply:

Make sure the water supply to the tankless water heater is turned on and that there are no blockages in the pipes. If the water supply is on and the unit still isn’t working, you may need to check the water filter for any clogs or damage. 


Check for error codes:

Many tankless water heaters have built-in error codes that will display on the unit’s screen if something is wrong. Check the owner’s manual for your specific unit to see what each error code means and how to troubleshoot it. 


Check the temperature settings:

If the water coming out of the unit is not hot enough, check the temperature settings on the unit. Some models allow you to adjust the temperature easily, while others may require a professional to adjust the settings. 


Check for mineral buildup:

If your area has hard water, it’s possible that mineral buildup could be causing your tankless water heater to malfunction. Check the unit’s manual for instructions on how to descale the unit and remove any mineral buildup. 


Call a professional:

If you’ve checked all of the above and your tankless water heater still isn’t working, it’s time to call a professional. A licensed plumber or HVAC technician can diagnose the problem and make any necessary repairs or replacements. 


In conclusion, if your tankless water heater is not working, don’t panic. Check the power source, gas supply, water supply, error codes, temperature settings, and for mineral buildup before calling a professional. Regular maintenance and inspections can also help prevent future issues with your tankless water heater. 


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