Instant water heater problems

7 Common Instant Water Heater Problems and Their Solutions

Instant water heaters, or tankless water heaters, have gained immense popularity for their energy efficiency and the convenience of on-demand hot water. While these systems are generally reliable, users may encounter several issues that could affect their performance. Therefore, discussing the instant water heater problems in detail is necessary. This detailed guide will explore seven common instant water heater problems, providing in-depth explanations and extensive solutions to help users troubleshoot and maintain their units for optimal functionality.

How to Fix Instant Water Heater Problems

Instant water heater issues are less complex than one might think. However, You need to have the fundamental knowledge and understanding of the basic plumbing techniques to fix instant water heater issues. 

This section will discuss the common problems of instant water heaters and their probable solutions. Furthermore, the causes of these common issues are also discussed in detail. Here is the list:

Insufficient Hot Water Output


Insufficient hot water output is the most talked about complaint among instant water heater users. This issue is usually related to either the unit’s capacity not aligning with the household’s demand or a scaled-up heat exchanger affecting the system’s efficiency.


Start by confirming that your instant water heater’s capacity suits your household’s hot water requirements. The problem may lie in a scaled-up heat exchanger if the capacity is sufficient. 

Regular descaling using manufacturer-recommended options is essential to restore the unit’s efficiency and improve hot water output. 

Consider hiring a professional to determine the appropriate capacity for your household if needed.

Fluctuating Water Temperature


Some frustrating instant water heater problems include fluctuations in water temperature that often occur due to variations in the water flow rate. Maintaining a consistent temperature becomes challenging when the flow rate surpasses the heater’s capacity.


Adjust the water flow rate to match the unit’s capacity. Furthermore, installing a flow restrictor can help stabilize water temperature by preventing the flow rate from exceeding the heater’s capabilities. 

Educating household members about the optimal flow rate is critical to ensure the system operates effectively. Periodically monitor and adjust the flow rate to maintain consistent hot water temperatures.

Instant water heater issues

Mineral Buildup and Scaling


Mineral buildup and scaling are common problems of instant water heaters, especially in areas with hard water. Over time, these deposits accumulate in the heat exchanger, limiting the efficiency.


Execute a regular maintenance routine. Regularly flush the system and use descaling solutions recommended by the plumbing services Singapore and the manufacturers to break down mineral deposits. 

This proactive approach improves the unit’s performance and extends its lifespan. Consider installing a water softener if you reside in an area with a consistent hard water issue. Learn more about the water hardness level in your area to determine the suitable frequency for descaling.

Ignition Failure


Ignition failures can cause a lack of hot water. Causes of ignition failure include closed gas valves, low gas pressure, or issues with the ignition components.


Check the gas supply, ensure the gas valve is open, and ensure the pressure meets specifications. Clean and inspect ignition components for faults. If issues persist, you may require professional assistance to diagnose and repair the ignition system effectively. 

Regular inspections and maintenance of the gas supply system are crucial for preventing ignition failures. Consider scheduling professional inspections annually to ensure the gas supply system is in optimal condition.

Water Leaks


Water leaks are a massive concern that can lead to damage. Leaks may occur at connections, fittings, or internal components. To fix instant water heater issues like this, you may need the assistance of plumbing services Singapore. Here is a proposed solution to this issue.


Thoroughly inspect the unit for visible leaks. Secure loose connections and replace damaged parts, such as gaskets or valves. If leaks persist, consult a technician immediately to identify and resolve the root cause, preventing further damage. 

Regular visual inspections and vigilance can help catch possible leaks before they escalate. Encourage a proactive approach by setting up a routine inspection and maintenance schedule, including a thorough check for potential leaks.

How to fix Instant water heater problems

Gas Flow Issues


Gas-powered instant water heaters may face issues due to inappropriate gas flow because of leaks, closed valves, or inadequate pressure.


Check the gas line for leaks, verify the valve is open, and confirm that the pressure meets the manufacturer’s specifications. If you are uncertain about gas-related troubleshooting, seeking professional assistance will be a wise choice to avoid safety hazards. 

Regular checks of the gas supply system are essential for maintaining the heater’s efficiency and safety. Make a checklist for periodic inspections, including gas line assessments and pressure checks, to resolve potential issues early on.

Strange Noises


Unusual noises, like rattling or banging, are an indication of internal issues such as sediment buildup or a faulty heating element.


Regularly flush the system to remove sediment and check the heating element for damage. This preventive maintenance can avoid common problems of instant water heaters. If unusual noises persist, consult a technician to examine internal components thoroughly. 

Furthermore, installing a water softener to minimize sediment buildup over time is a good investment. Develop a vigilant maintenance plan, including regular flushing and internal component inspections, to resolve potential issues before they result in strange noises.


Instant water heater problems are resolvable through a DIY approach, but you need to know the fundamentals to succeed. Moreover, regular maintenance and prompt attention to issues are essential to ensuring the optimal performance of your instant water heater. Understanding and addressing these common problems can extend the lifespan of your unit, and enjoy a reliable and efficient hot water supply in your home. If you encounter persistent or intricate issues, hiring a qualified technician is always recommended to ensure a safe and effective resolution.

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