Tankless water heaters are popular household appliances that provide hot water on demand. These appliances warm up water only as needed and do not generate standby heating losses common among large storage tanks. According to the U.S. Department of Energy, tankless water heaters are up to 24%–34% more energy efficient than traditional water heaters. They are also popular for their compact sizes, lower maintenance, and extended lifespan. A beeping water heater is one of the first indicators that something has gone wrong. But what are the possible causes of these audible alarms? A look at the top reasons that tankless water heaters beep can guide you on the best ways to rectify any issues.

Limescale Buildup

While conventional water heaters are more notorious for buildup, tankless water heaters can also experience various degrees of mineral buildup. Depending on where you live, your water may contain high concentrations of minerals like calcium and magnesium. Groundwater can absorb these minerals from local soil, thereby increasing mineral content. Scientists refer to water with high levels of mineral content as “hard water.” The U.S. Geological Survey measures water hardness by the concentration of mineral carbonates in milligrams per liter. For example, standard classifications for residential hard water are as follows:

  • Soft water: 0-60 mg/L
  • Moderately hard water: 61–120 mg/L
  • Hard water: 121–180 mg/L
  • Very hard water: Greater than 181 mg/L

If the mineral concentration of your water is 121 mg/L or higher, you may experience limescale buildup in pipes and plumbing appliances. This accumulation of minerals can affect the performance of your tankless water heater and eventually cause it to beep.

Water Leak Detection

Tankless water heaters also start beeping if the system detects a water leak. Signs that you have an actual leak include water pooling on the floor or within the appliance’s casing. You may also find that the unit becomes inefficient or goes into automatic shut-off mode. Although tankless water heaters do not have storage tanks that potentially seep water, leaking can occur from the heat exchanger or the pipework.

Reach out to a plumber to fix any damage. Even if there is no water outside of the unit, the plumber can also check whether the leak sensor itself is defective. Sometimes the sensor becomes defective due to loose wiring, faulty connections, or moisture exposure. A plumber can replace the defective sensor so that your tankless water heater functions normally again.

Gas Leak Detection

If you have a gas-powered tankless water heater, any gas line defects may increase the likelihood of leaks. If you hear beeping and begin to smell a rotten egg odor, it is time to shut off the gas supply and contact a professional immediately. Extreme concentrations of natural gas can cause unsafe carbon monoxide exposure and result in illness or death, so it is important to resolve gas leakage as quickly as possible.

Evaporator Coil Leak Detection

If your tankless water heater is electric, beeping may indicate leakage in the evaporator coil. This can result in refrigerant loss and inhibit the full operation of your unit. As a result of evaporator coil failure, the corresponding compressor might collapse. A plumber can diagnose and repair evaporator coil problems.

Excessive Heat or Pressure

A malfunctioning heating element or temperature sensor can overheat your water. If the temperature exceeds recommended levels, this scalding water can burn the skin and pose other health risks. Many tankless water heater models come with a signifier that beeps and shuts the unit down if temperatures have risen too high. Similarly, all tankless water heaters have a maximum pressure level for safe operation. If the pressure near any valves, lines, or inlets has risen too high, the unit may provide a beeping alert.

Insufficient Water Flow Rate

A sufficient water flow rate is essential for the best performance of your tankless water heater. The term “water flow rate” refers to the volume of fluid that comes out of your appliance per unit of time. This rate is important since part of the point of a tankless unit is to supply hot water instantaneously. Manufacturers specify the minimum flow rate of their water heater models in increments of gallons per minute (GPM). Whether electric or gas, all tankless water heaters have a designated minimum flow rate. Each unit must reach this minimum flow rate to open the unit’s flow switch. If your current water flow rate is lower than the designated minimum, the flow switch will not open, and the heater or burner will not ignite.

Excessive Flow Rate

Just as the tankless water heater has a minimum flow rate, it also has a maximum flow rate capacity that indicates the recommended amount of hot water members of the household can use at the same time. If you exceed the maximum flow rate capacity for your unit, there is a risk of system overload. Consequently, the water heater may not be able to meet the demands of the building concurrently. The tankless water heater may beep and then shut down to prevent system blowouts or major damage. Talk to your local plumber about choosing and installing a tankless water heater that matches the simultaneous demands within your household.

Air Blockage

Your tankless water heater has components that regulate the intake and output of air for effective operation. These components include an air intake valve responsible for providing enough oxygen for the combustion process. This combustion allows your unit to heat enough water properly. The tankless water heater also has a fan that helps draw air in from the exterior as well as an exhaust vent that releases waste gases after the combustion process is complete.

If the air intake valve, fan, or exhaust vents are defective, the tankless water heater may start beeping to signify the error. A plumber can inspect the unit and diagnose issues. For example, the plumber may determine that a malfunctioning intake valve or broken fan has prevented the unit from drawing in enough air. The plumber can then perform troubleshooting and make repairs if necessary. Likewise, blockage to the exhaust vent can trap dangerous gases inside the system. This accumulation of gas is a safety hazard, and some models have an automatic shut-off mechanism to prevent explosions.

Get Help From the Experts

Beeping noises from your tankless water heater may indicate several alarming problems. Fortunately, the experts are here to help. High 5 Plumbing, Heating & Cooling provides water heater services for homes in Denver and surrounding areas. We offer professional tankless water heater installation, and our maintenance sessions can diagnose any error codes and perform the necessary repairs. You can count on us to address any odd noises, leaks, or problems from your existing unit. We also work with traditional tank water heaters and can answer any questions about making the switch to an on-demand water heater instead.

Known for superior customer service, we offer kitchen plumbing, bathroom plumbing, outdoor plumbing, and gas plumbing solutions. No matter the type of appliance, our experts can do the job. Contact High 5 Plumbing, Heating & Cooling for all water heater or plumbing needs.

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