Introduction
Tankless water heaters, often called on-demand water heaters, have become a popular choice for homeowners seeking energy efficiency and endless hot water. Unlike traditional storage tanks, they heat water only when you turn on the tap. But with their advanced technology, many homeowners wonder: Does a tankless water heater need maintenance? The short answer is yes—and proper care is the key to keeping your investment running smoothly.
How Tankless Water Heaters Work
Difference Between Tankless and Traditional Water Heaters
Traditional water heaters store hot water in a large tank, reheating it continuously. Tankless units, on the other hand, heat cold water instantly as it passes through a heating element or gas burner. This design reduces standby energy loss and provides unlimited hot water.
Why Tankless Systems Are Popular Today
- Energy Savings: Tankless systems heat water only when needed, eliminating the energy loss associated with keeping a tank of water hot 24/7. This results in noticeable reductions in energy bills.
- Compact Design: These systems have a smaller footprint than traditional tank water heaters, making them ideal for homes with limited space or for installation in tight areas.
- Longer Lifespan: Tankless water heaters typically last longer than conventional tank systems, offering years of reliable performance with proper maintenance.
- Consistent Hot Water Supply: Because water is heated on demand, users enjoy a steady supply of hot water without the risk of running out, even during peak usage, making it ideal for Heat Pump Installation.
Do Tankless Water Heaters Require Maintenance?
Yes—just like any other appliance, tankless water heaters require routine maintenance. While they are more durable and efficient than storage tanks, they are not maintenance-free. Neglecting upkeep can lead to mineral buildup, reduced efficiency, and costly repairs.
Common Misconceptions About Tankless Systems
- “They never need servicing.”
- “Flushing is only necessary in hard water areas.”
- “Tankless units last forever without care.”
Manufacturer Recommendations for Maintenance
Most manufacturers recommend scheduling maintenance once a year to keep performance steady and protect the warranty. Annual service typically includes descaling, filter cleaning, and a quick safety inspection of gas and venting components. If your home has hard water, you may need to flush the unit every.
Types of Maintenance for Tankless Water Heaters
Annual Descaling and Flushing
Descaling removes mineral deposits that form inside the heat exchanger and restrict heat transfer. When scale accumulates, the unit works harder to reach the set temperature, which can increase energy use and shorten component life. Flushing once per year is the baseline, but hard-water homes often need it more frequently to maintain efficiency.
Why Mineral Buildup Happens
Hard water contains minerals like calcium and magnesium that are harmless to drink but problematic when heated. As water temperature rises, dissolved minerals can precipitate out and cling to heated metal surfaces inside the unit. Over time, those deposits narrow internal passages, reduce flow, and create hot spots that stress the heat exchanger.
Step-by-Step Flushing Process
1. Turn Off Power and Gas
Shut off electrical power to the unit so it cannot ignite or run while you are working. Close the gas valve fully on gas models to eliminate the risk of leaks or accidental firing. Let the unit cool for a few minutes so you aren’t handling hot water lines or hot internal components.
2. Close Water Valves and Connect Hoses
Close the cold-water inlet and hot-water outlet isolation valves to separate the unit from the home’s plumbing. Connect hoses to the service ports and route them to a bucket so you can circulate and capture the flushing solution. Check fittings for tight seals because small leaks can turn into a messy spill once the pump starts.
3. Prepare the Flushing Solution
Place a submersible pump in a bucket and connect the hoses so the solution can circulate through the heater and back into the bucket. Use white vinegar or a manufacturer-approved descaling chemical at the recommended concentration. Avoid harsh chemicals that can damage internal seals or leave residues that are difficult to rinse out.
4. Flush the System
Run the pump to circulate the solution for about 45–60 minutes, or as specified by the manufacturer. During circulation, the solution dissolves scale and carries loosened mineral particles out of the heat exchanger. If the solution becomes very cloudy or gritty quickly, that can indicate heavy buildup and may warrant a longer cycle or a repeat flush.
5. Rinse and Restore Power
Drain the descaling solution and flush clean water through the system until the water runs clear and odor-free. Remove the hoses, close service ports securely, and reopen the isolation valves to return the unit to normal plumbing operation. Restore gas and power, then run hot water for a few minutes to confirm stable temperature and normal operation.
Cleaning the Air and Water Filters
Filters prevent dust, dirt, and debris from entering the unit. A clogged filter can restrict airflow or water pressure. Cleaning every few months ensures proper performance.
Inspecting and Servicing Venting Systems
Proper venting is critical for gas tankless heaters because it safely carries exhaust gases out of the home. A blocked, disconnected, or poorly sloped vent can cause performance issues and may create a serious carbon monoxide risk. Regular inspection helps catch corrosion, obstructions, and loose connections before they become safety hazards.
Checking Gas and Electrical Connections
Loose wiring, worn gaskets, and aging connectors can cause intermittent failures, error codes, or complete shutdowns. Gas leaks are especially dangerous, so fittings and valves should be checked with appropriate methods during annual service. Having a professional inspect these components reduces risk and ensures the unit meets safety standards.
Signs Your Tankless Water Heater Needs Maintenance
Reduced Water Flow or Low Pressure
A noticeable drop in hot-water pressure can indicate scale, a clogged inlet screen, or debris in the water pathway. As passages narrow, the unit may limit output to protect itself, which feels like weaker flow at fixtures. If only hot water is affected, maintenance is a likely solution; if both hot and cold are low, the problem may be elsewhere in the plumbing.
Inconsistent Water Temperature
Temperature swings often happen when scale interferes with heat transfer or when sensors detect unstable operating conditions. You may feel brief bursts of cold water, especially during longer showers or when multiple fixtures run at once. Flushing, filter cleaning, and a professional diagnostic check can typically restore stable temperature control.
Strange Noises
Clicking, hissing, or rumbling can occur when scale causes uneven heating and tiny steam bubbles form and collapse. Noises can also point to airflow restriction, fan issues, or components struggling to operate under strain. If sounds are new or growing louder, schedule maintenance before the issue escalates into a breakdown.
Error Codes on the Control Panel
Error codes are the unit’s way of reporting abnormal conditions like restricted flow, ignition problems, or venting faults. Some codes clear after basic maintenance, such as cleaning filters or restoring proper water flow, while others require professional troubleshooting. If codes repeat after a reset, treat it as a maintenance or safety issue rather than continuing to ignore it.
How Often Should You Maintain a Tankless Water Heater?
Maintenance Frequency by Water Hardness
- Soft Water Areas: In regions with soft water, maintenance is typically required every 12–18 months.
- Hard Water Areas: In areas with hard water, more frequent maintenance is necessary, usually every 6–9 months.
Residential vs. Commercial Use
- Residential Homes: For most households, servicing once a year is sufficient. Regular annual maintenance helps ensure systems operate efficiently and prevents unexpected issues.
- Commercial Buildings: Due to heavier usage, commercial properties typically require servicing every six months. Frequent inspections and maintenance help maintain performance and reduce the risk of costly downtime.
DIY vs. Professional Maintenance
Pros and Cons of DIY Maintenance
- Saves money
- Good for basic flushing and filter cleaning
- Risk of mistakes that void warranties
- Not recommended for complex gas/electrical checks
When to Call a Licensed Plumber
- Gas or propane-powered units
- Electrical issues
- Strange noises or error codes that persist after flushing
Cost of Maintaining a Tankless Water Heater
Average Cost of Professional Service
Basic flushing usually costs between $100 and $200 when a technician performs a standard descaling and rinse. A full service with inspection typically ranges from $200 to $350, often including checks for ignition, venting, filters, and error codes. Your final price varies based on the scope of work, access to the unit, and the size/needs of the property.
Long-Term Savings from Proper Maintenance
Preventing mineral buildup helps the heater run correctly, which reduces wear on internal components and lowers the chance of premature failure. By catching small issues early, homeowners can avoid expensive repairs like damaged heat exchangers, sensors, or valves. Over time, proper maintenance can save hundreds on repairs and potentially thousands by delaying full replacement.
Benefits of Regular Tankless Water Heater Maintenance
Improved Energy Efficiency
Maintenance reduces scale buildup on the heat exchanger, allowing heat to transfer more effectively with less energy. When the system is clean, it reaches target temperatures faster and cycles more smoothly, which cuts down on wasted fuel or electricity. This typically translates into lower utility bills, especially in homes with hard water.
Longer Lifespan of the Unit
Routine flushing and inspections reduce stress on critical components, which can meaningfully extend the heater’s operating life. With proper care, many units last longer than neglected systems because they avoid corrosion, overheating, and restricted flow issues. Homeowners often gain an extra 5–10 years of reliable service by sticking to a maintenance schedule.
Consistent Hot Water Supply
Cleaning filters and flushing mineral deposits helps maintain steady flow rates and stable heating performance. That consistency reduces temperature swings, cold bursts, and delays when multiple fixtures run at once. As a result, the system is more likely to deliver dependable hot water during peak usage.
Lower Risk of Costly Repairs
Regular service helps spot early warning signs like minor leaks, unusual burner behavior, error codes, or declining flow. Fixing these small problems early prevents major failures that can require costly parts or full unit replacement.
Mistakes to Avoid During Maintenance
- Skipping annual flushing
- Using harsh chemicals instead of vinegar or descaler
- Ignoring manufacturer guidelines
- Attempting gas or electrical repairs without training
Tankless Water Heater Maintenance Checklist
- Flush the system annually
- Clean air and water filters
- Inspect the venting and exhaust system
- Check gas/electrical connections
- Monitor for error codes or unusual noises
FAQs
How often should a tankless water heater be flushed?
Most tankless water heaters should be flushed at least once per year to remove mineral scale and keep heat transfer efficient. If you’re in a hard-water area, flushing every 6–9 months is a safer cadence because scale forms faster and can clog the unit. Homes with high hot-water usage may also benefit from more frequent flushing, even if the water isn’t extremely hard.
Can I flush my tankless water heater myself?
Yes, many homeowners can flush a tankless unit themselves using a pump, hoses, and a descaling solution, as long as they follow the manufacturer’s steps exactly. The biggest risks are skipping shutoff steps, using the wrong chemicals, or damaging valves and connections during reassembly. If your unit has gas components, ignition issues, electrical faults, or you’re unsure about any step, hiring a pro is the safer route.
What happens if you don’t maintain a tankless water heater?
Without maintenance, mineral buildup insulates the heat exchanger, forcing the system to work harder and use more energy to heat the same amount of water. That extra strain can lead to overheating, reduced flow, inconsistent temperatures, and premature failure of internal parts. Over time, neglected units often need expensive repairs (or replacement) that routine flushing would have prevented.
Do electric tankless water heaters need the same maintenance as gas ones?
Yes—electric and gas tankless water heaters both need regular flushing and inlet filter cleaning to prevent scale and blockage. The key difference is that gas units also require venting checks, combustion inspection, and gas-line safety verification to ensure they’re operating safely. Electric models skip venting concerns, but still need periodic inspection of heating elements and electrical connections if performance drops.
How long does a tankless water heater last with proper maintenance?
With consistent flushing and routine service, many tankless water heaters can last 20 years or more, depending on water quality and usage. Regular maintenance reduces scale damage and helps components like sensors, valves, and the heat exchanger stay within normal operating ranges. By comparison, traditional tank water heaters commonly last around 10–12 years because stored water accelerates corrosion and sediment buildup.
Is professional maintenance worth the cost?
Yes—professional maintenance typically pays off by improving efficiency, catching small issues early, and helping the unit run safely and reliably. A technician can also inspect gas pressure, venting, combustion, error codes, and internal components that DIY flushing doesn’t fully address. Over the long term, annual servicing often costs less than a major repair, prolonged inefficiency, or early replacement.
Conclusion
So, does a tankless water heater need maintenance? Absolutely. Just like any other major home appliance, regular upkeep is essential. From flushing mineral buildup to checking filters and connections, maintenance ensures efficiency, reliability, and a long service life. Whether you DIY the basics or call a professional, staying proactive will keep your water heater performing at its best for decades. Contact RHCC to schedule professional maintenance and keep your system running efficiently.
