Tankless water heaters are an excellent option for energy-efficient, on-demand hot water, but they are not immune to failures. Although most of these units are long-lasting and reliable, there are a few critical issues that can crop up from time to time. Luckily, a little bit of knowledge about common failures can help you stop water heater failures from breaking the bank.
Two typical reasons for a gas-powered heater to shut down are blocked air or exhaust vents. Like any natural gas appliance, your water heater requires a continuous source of oxygen for combustion, as well as a clear path to remove harmful exhaust gases from your home. Without both of these elements, the safeties in your water heater will likely shut it down.
Understanding Air Intake Problems
Without a steady supply of fresh air, your water heater's burner may fail to ignite or burn inconsistently. On older designs, a lack of proper airflow could cause the pilot to go out. Since newer water heaters and tankless systems typically use electronic ignition, this is no longer a concern. Inadequate airflow still can and will prevent the main burner from igniting, however.
Your tankless water heater includes an air filter that can become obstructed over time. Regularly cleaning or replacing this filter helps to ensure that sufficient air reaches the combustion chamber. A clogged filter can also cause the intake blower motor in your tankless heater to overheat and fail, ultimately stopping the burner from functioning at all.
You can check your filter as a part of routine maintenance, but you should really on a professional plumber to inspect your blower motor. In some cases, blower motor failures may be the result of wiring problems or other relatively minor issues that a professional can fix without replacing the entire blower.
Understanding Exhaust Problems
Just like your furnace, gas drier, or any other gas appliance, your tankless water heater must be able to vent combustion gases to an exterior space. If the exhaust vent becomes blocked, modern tankless water heaters will shut down and throw an error code. You can check any displayed error codes in your user's manual to determine if this is the reason that your water heater has shut down.
Since exhaust vents route outside of your home, vents often become clogged due to yard waste such as leaves or twigs. Rodents and other pests can also sometimes enter exhaust plumbing, leaving behind obstructions that can prevent the free flow of air. If you cannot see an obvious problem, it's often a good idea to consult with a plumber and arrange for a professional cleaning.
It can be disheartening when an expensive tankless water heater stops working, but the causes are often relatively minor and easy to fix. Recognizing the signs of intake and exhaust airflow problems can help you quickly and cheaply resolve some of the most common reasons for tankless water heater malfunctions.