Tankless Water Heater Problems (Not Working & Other Issues)

Tankless water heaters not working and other problems are common concerns for homeowners. These issues can range from minor inconveniences to significant malfunctions requiring professional attention.

Tankless water heaters, known for their efficiency and on-demand hot water supply, can encounter various problems. Maintenance is key to their optimal performance. Essential tasks include cleaning or replacing the water line filter, ensuring the air filter is free of debris, and performing regular flushing or descaling every six months.

Descaling is crucial, especially in areas with hard water, to prevent mineral buildup. It’s recommended to use 2.5 gallons of white vinegar for this process, avoiding harsh chemicals that can damage the system.

Annual maintenance is advised to keep tankless water heaters in top condition, especially for models like Navien. This regular check-up can help identify issues before they escalate. If your heater isn’t working, the reset button, typically found on the front or right side, can be a quick fix. All heaters have a reset option, often near the thermostat, for safety and troubleshooting.

One peculiar issue is the malfunctioning of heaters after rain. This can be due to moisture affecting the electrical components or sensor mats around the heat exchanger. In cold climates, tankless heaters can freeze if not properly insulated, leading to damage. Draining the unit when away for an extended period can prevent this.

Noise from the heater, like a jet engine, often indicates sediment buildup or fluctuating water pressure. Regular draining and flushing can mitigate this. A dirty flow sensor, responsible for gas regulation, can also cause such noises.

Gas smells from the heater, especially from the exhaust, signal a possible leak. This is a serious safety concern and should be addressed immediately. Low water pressure can also affect the heater’s functionality, as it relies on a certain pressure level to operate efficiently.

When troubleshooting, ensure the power supply and gas connections are secure. Check for blocked exhaust systems, which can prevent the heater from turning on.

For specific models like Rinnai, Rheem, Eemax, Ecosmart, Noritz, AO Smith, and others, refer to the manufacturer’s guidelines for troubleshooting and maintenance.

Related: The 8 Best Tankless Water Heaters

Table of Contents

Is There a Reset Button on a Tankless Water Heater?

Most tankless water heaters are equipped with a reset button, an essential feature for troubleshooting and safety. This button is typically located on the front panel or side of the unit, though its position can vary depending on the brand and model.

The purpose of this button is to allow users to quickly reset the water heater in case of a malfunction or after resolving an issue that caused the heater to shut down or malfunction.

The reset button is part of the heater’s built-in safety mechanisms. It usually gets triggered when the water temperature exceeds a safe limit, indicating an overheating problem. Overheating can be caused by a variety of issues, such as a malfunctioning thermostat, a blocked vent, or a faulty heating element.

Pressing the reset button helps in restoring normal operation, but it’s crucial to understand that it’s a temporary solution. If the heater continues to trip the reset button, it indicates an underlying problem that requires attention.

Regular maintenance and timely troubleshooting are key to avoiding the need for frequent resets. This includes checking for any blockages, ensuring proper venting, and regularly cleaning the filters and burners.

Tankless Water Heater Not Working After Rain!

Tankless water heaters might experience operational issues after heavy rain, which can be perplexing and inconvenient for homeowners. The reasons for malfunction after rainfall can vary, but common causes include water infiltration into the unit or its components, moisture affecting the electrical system, or issues with the venting system.

Rainwater can enter the unit if the venting system is not adequately sealed or if the heater is installed in a location that’s prone to flooding or water accumulation. This moisture can cause short circuits or corrosion in the electrical components, leading to malfunction.

Another issue could be the venting system getting partially blocked by rainwater or debris brought by strong winds, which impedes the proper functioning of the heater.

To prevent these problems, ensure that the tankless water heater is installed in a location protected from direct rain exposure. The venting system should be checked regularly for leaks or blockages, and the installation should comply with the manufacturer’s guidelines to prevent water ingress.

After heavy rain, inspect the unit for any signs of water or moisture and ensure that all electrical connections are dry.

Do Tankless Water Heaters Freeze in Cold Weather?

Tankless water heaters, despite their advanced technology, are not immune to the effects of freezing temperatures. In cold weather, especially in climates where temperatures drop below freezing, these heaters can be at risk of freezing if proper precautions are not taken. This is a concern because the water inside the unit can freeze, expand, and potentially cause damage to the internal components.

To prevent freezing, it’s essential to ensure that the heater is installed in a location that remains above-freezing temperatures or is adequately insulated. Many modern tankless water heaters come with built-in freeze protection systems that help protect the unit down to certain temperature thresholds.

However, these systems rely on electrical power, so in the event of a power outage, additional protection is necessary.

Insulation of the pipes leading to and from the heater is crucial in preventing freezing. Homeowners can use pipe insulation sleeves or heat tape to protect exposed pipes. If the heater is installed in an unheated area like a garage, consider adding additional insulation or a space heater to maintain a safe temperature.

During prolonged absences in winter, it’s advisable to drain the water heater to prevent any water left inside from freezing.

Do Tankless Water Heaters Freeze in Cold Weather

8 Probable Causes Tankless Water Heater Not Working and Solutions

Tankless water heaters, renowned for their efficiency and space-saving design, can sometimes run into operational issues. Understanding these common problems and their solutions can help ensure your unit runs effectively for years.

1. Inadequate Heating

A frequent issue with tankless water heaters is inadequate heating. This might be due to an overload in demand, where the heater cannot supply enough hot water for multiple simultaneous uses.

To fix this, limit the number of hot water applications used at once. If the problem persists, the unit might be undersized for your needs, and upgrading to a model with a higher capacity might be necessary.

2. System Overload

System overload occurs when the water heater is tasked with more hot water demand than it can handle. This is common in larger households or those with high hot water usage. The solution is to manage the simultaneous use of hot water appliances or consider installing a second tankless water heater to distribute the load.

3. Mineral Buildup

In areas with hard water, mineral buildup can significantly impact the efficiency of tankless water heaters. The accumulation of calcium and magnesium can block the flow of water and reduce heating efficiency. Regular descaling with a vinegar solution can prevent this issue. It’s advisable to perform descaling annually, or more frequently in areas with very hard water.

4. Ignition Failure

Ignition failure in tankless water heaters can be due to several factors, such as gas supply issues or faulty igniters. Ensure the gas valve is fully open and the gas line is supplying sufficient fuel. If the issue is not with the gas supply, the igniter may need to be replaced. Regular maintenance checks can prevent these issues by ensuring all components are functioning correctly.

5. Flame Failure

Flame failure could be due to problems with the gas supply, venting, or the heater’s flame sensor. First, check that the gas pressure is sufficient and there are no obstructions in the vent. If these are fine, cleaning the flame sensor might resolve the issue. If the problem persists, the sensor might need replacement.

6. Exhaust Blockage

An exhaust or air intake blockage can cause the heater to shut down as a safety measure. Check the venting system for any obstructions, such as bird nests or debris. Regular inspections of the venting system can help identify and resolve such blockages promptly.

7. Electrical Issues

Electrical problems, such as tripped breakers or faulty wiring, can lead to the heater not functioning. Check the electrical panel for any tripped circuits and ensure the heater is properly wired and grounded. If the problem is not immediately apparent, consulting with an electrician is recommended.

8. Cold Water Sandwich

The ‘cold water sandwich’ effect happens when hot water is followed by a sudden burst of cold water, then hot again. This is typical in tankless systems when there’s intermittent demand for hot water. There’s no direct fix, but understanding and anticipating this phenomenon can help manage its occurrence during usage patterns.

Tankless Water Heater Sounds Like a Jet Engine!

A tankless water heater making noises similar to a jet engine is an indication that something is amiss. This noise is often a result of high water velocity through the unit, sediment buildup, or issues with the burner or fan. These sounds should not be ignored, as they can be a symptom of a problem that might worsen if left unaddressed.

Sediment buildup is a common cause of noise in tankless water heaters. Over time, minerals from hard water accumulate inside the unit, leading to efficiency problems and noise.

Performing regular descaling and flushing of the unit can help prevent this buildup. Descaling involves circulating a solution, typically white vinegar, through the system to dissolve and remove the mineral deposits.

If the noise is more of a whirring or fan-like sound, it could be related to the burner or fan components. An obstructed or dirty fan can struggle to maintain the correct speed, resulting in unusual sounds.

Similarly, if the burner is dirty or malfunctioning, it can create an uneven flame pattern, leading to noise. Regular cleaning and maintenance of these components are necessary to prevent such issues.

Tankless Water Heater Smells Like Gas: What to Do?

Identifying the Source

The first step when you notice a gas smell is to identify the source. Check around the tankless water heater for any signs of leaks. This could be at the connections, along the gas line, or near the unit itself. Gas leaks are serious safety hazards and should be addressed immediately.

Safety Measures

If you detect a strong gas smell, it’s crucial to act swiftly and safely. Avoid igniting any flames or operating electrical switches which could trigger an explosion. Open windows and doors to ventilate the area and immediately shut off the gas supply to your heater, if possible.

Professional Inspection

For safety reasons, it’s advisable to contact a qualified technician to inspect your tankless water heater. A professional can safely identify and repair any gas leaks. They will also check the venting and combustion process to ensure everything is functioning correctly.

Preventive Tips

Regular maintenance of your tankless water heater can prevent gas leaks. This includes checking the connections and ensuring the venting system is clear and properly installed. Annual inspections by a professional can help catch any potential issues early on.

Draining a Tankless Water Heater: Step by Step

Step 1: Turn Off Power

Ensure the power supply to the tankless water heater is completely shut off. This includes turning off the electricity at the circuit breaker or shutting off the gas supply for gas-powered models.

Step 2: Close Water Valves

Close the cold water inlet valve to stop the flow of water into the heater. Also, shut off the hot water valve to prevent water from exiting the unit during the draining process.

Step 3: Attach a Hose

Connect a hose to the drainage valve of the water heater. Make sure the other end of the hose is placed where the water can safely drain, such as a floor drain or an outdoor location.

Step 4: Open the Drain Valve

Open the drain valve to allow the water inside the tankless water heater to flow out through the hose. Ensure that the water drains completely.

Step 5: Flush the System

To remove any buildup or sediment, flush the system with clean water. This can be done by opening the cold water valve for a few minutes while the drain valve is still open.

Step 6: Close the Drain Valve and Disconnect Hose

Once the system is drained and flushed, close the drain valve and disconnect the hose.

Step 7: Restore Power

Open the cold water valve to allow the tank to fill back up. Then, restore power to the unit by turning on the electricity or gas supply.

Electric Tankless Water Heater Not Getting Hot Enough

Several factors can cause an electric tankless water heater to underperform in terms of heating water. One common issue is the buildup of scale and sediment, particularly in areas with hard water. This buildup can insulate the heating elements, reducing their efficiency. Regular descaling and maintenance are necessary to prevent this.

Another possible cause is an electrical issue, such as a tripped breaker or a malfunctioning heating element. Check your circuit breaker and reset if necessary. If the problem persists, the heating element may need to be inspected or replaced.

The size and capacity of the heater also play a critical role. If the unit is too small for your household’s hot water demands, it will struggle to provide sufficient heat. Assess your hot water needs and ensure your tankless water heater is appropriately sized.

Incorrect installation or settings can also lead to heating issues. Ensure that your water heater is installed according to the manufacturer’s guidelines and that the temperature settings are correctly adjusted for your needs.

Tankless Water Heaters Maintenance

Regular Inspection

Perform a visual inspection of your tankless water heater regularly. Look for any signs of wear, leaks, or damage. Check all connections, the venting system, and the exterior of the unit for any abnormalities.

Descaling and Flushing

In areas with hard water, mineral buildup can affect the efficiency of your heater. Descaling involves using a special solution, like white vinegar, to dissolve and flush out these minerals. This process should be done annually or as recommended by the manufacturer.

Filter Cleaning

Many tankless water heaters have in-line filters that should be cleaned regularly. These filters can become clogged with debris, affecting the flow of water and the efficiency of the heater.

Checking the Ventilation

Proper ventilation is crucial for the safe operation of a tankless water heater. Ensure that the venting system is clear of obstructions and functioning correctly to prevent issues like gas leaks or inefficient combustion.

Professional Servicing

Apart from routine maintenance tasks you can perform, it’s recommended to have your tankless water heater professionally serviced at least once a year. This ensures that all components are in good working order and can help extend the lifespan of the unit.