Tankless Water Heater Maintenance
Whether your unit is gas or electric, learning how to maintain it helps ensure consistent hot water for showers, laundry, dishes, and everyday comfort.
Tankless water heaters deliver endless hot water, save energy, and take up less space than traditional tank models. But like any mechanical system, a tankless water heater needs regular maintenance to operate reliably year after year. Proper care prevents breakdowns, extends service life, maintains peak efficiency, and protects your investment.
This complete homeowner’s guide covers why tankless water heater maintenance matters, how these systems work, the most important maintenance tasks, seasonal care tips, signs your system needs professional attention, and how to avoid costly repairs. Whether your unit is gas or electric, learning how to maintain it helps ensure consistent hot water for showers, laundry, dishes, and everyday comfort.
Why Tankless Water Heater Maintenance Is Important
Tankless water heaters are highly efficient because they heat water on demand. But mineral buildup, scale, sediment, and normal wear on internal components can reduce efficiency, restrict water flow, cause temperature fluctuations, or lead to system failure. Regular maintenance removes buildup, checks safety controls, and keeps components operating as designed.
Without maintenance, scale and sediment accumulate inside the heat exchanger and pipes, forcing the system to work harder and reducing its ability to deliver hot water consistently. Over time, this strain can increase energy costs, cause premature wear, and shorten the life of your tankless water heater.
How Tankless Water Heaters Work
Unlike traditional tank water heaters that store hot water, tankless systems heat water instantly as it flows through the unit. When you open a hot water tap, cold water enters the heater. A sensor detects the flow and activates burners or electric heating elements, raising the water temperature to the set level. Once the tap is closed, the system stops heating immediately.
Because there is no storage tank and no standby heat loss, tankless water heaters are more efficient and provide a virtually endless supply of hot water. But this on-demand operation means minerals and scale from hard water can build up rapidly in areas with higher mineral content unless the system is maintained.
Common Maintenance Tasks for Tankless Water Heaters
Routine maintenance keeps your system working efficiently and prevents common issues. The most important tankless water heater maintenance tasks include:
• Flushing the system to remove mineral buildup
• Cleaning or replacing inlet water filters
• Inspecting and cleaning the burner or heating elements
• Checking venting and safety controls
• Testing the temperature and pressure (T&P) safety valve
Let’s explore each task in more detail.
Flushing Your Tankless System to Remove Scale
Scale buildup inside the heat exchanger is one of the leading causes of performance problems. Hard water minerals cling to internal components, restricting heat transfer. Regular flushing removes this buildup before it affects efficiency or causes long-term damage.
To flush the system, you’ll need a pump, a bucket, and a cleaning solution or vinegar. The general process involves circulating the cleaning solution through the tankless unit for a period of time to dissolve mineral deposits. Afterward, the system is rinsed with clean water. Flushing is typically done annually, but in areas with very hard water, it may be needed more frequently.
Flushing restores efficient heat transfer, improves water flow, and helps prevent uneven heating or premature shutdowns.
Cleaning and Replacing Inlet Water Filters
Most tankless systems include inlet water filters that trap debris before it enters the heater. Over time, these filters can become clogged, reducing water flow and making the system work harder to meet hot water demand.
Regularly removing and cleaning these filters ensures unrestricted flow. If the filter shows signs of wear or damage, replacement helps maintain system performance. Cleaning filters is a quick maintenance task that can make a big difference in overall efficiency.
Inspecting Burners and Heating Elements
Gas and electric tankless water heaters have internal components that require periodic inspection and cleaning. In gas models, burners can accumulate dust and soot, reducing combustion efficiency. Electric units have heating elements that may accumulate buildup, reducing their ability to heat water quickly.
A routine inspection checks for corrosion, debris, or wear and allows you to clean or service these parts as needed. When burners or elements are in good condition, your system heats water more efficiently and consistently.
Checking Venting and Safety Controls
Proper venting ensures that combustion gases are safely expelled from gas tankless water heaters. Blocked or improperly installed vents can cause pressure issues, reduced efficiency, or unsafe operation. Regular inspection of venting pathways clears obstructions, ensures seals are tight, and helps verify that air intake and exhaust systems are working correctly.
Safety controls such as temperature sensors and pressure relief valves should also be tested and checked for proper operation. These components protect the system and your home from overheating, excessive pressure, and other potential hazards.
Seasonal Maintenance Tips
Maintenance schedules vary by location and usage, but generally, homeowners should perform major maintenance tasks at least once per year. Additional seasonal tips include:
• Before winter: Ensure outdoor units and exposed piping are protected from freezing, and check insulation on exterior lines.
• After heavy usage periods: Flush and inspect the system to remove extra buildup after summer family visits or holiday gatherings.
• During hard water seasons: Increase flushing frequency if you experience more mineral buildup during certain months.
Seasonal maintenance keeps your tankless water heater performing well year-round and prevents weather-related issues.
When to Call a Professional for Tankless Maintenance
While many maintenance tasks can be handled by knowledgeable homeowners, some situations warrant professional service:
• Persistent hot water temperature fluctuations
• Strange noises or system shutdowns
• Visible leaks or corrosion
• Difficulty flushing or clearing scale buildup
• Electrical or gas component concerns
Certified plumbers are trained to diagnose complex issues, perform detailed inspections, and complete maintenance safely and efficiently. Professional service protects your warranty, ensures code compliance, and extends system longevity.
Benefits of Regular Tankless Water Heater Maintenance
Maintaining your tankless system delivers clear long-term benefits:
• Increased energy efficiency and lower utility costs
• Consistent hot water delivery
• Extended unit lifespan
• Fewer emergency repairs
• Better protection from scale and mineral damage
Homeowners who invest in regular maintenance maximize the value and convenience of their tankless water heaters.
Tankless Water Heater Maintenance Questions Homeowners Should Not Ignore
How often should I maintain my tankless water heater?
Most tankless water heaters should receive maintenance once a year. Homes with hard water may need flushing and inspection every six months to prevent mineral buildup and performance issues.
Can I flush my tankless water heater myself?
Homeowners with basic tools and a proper descaling solution can flush a tankless system themselves. However, professional service provides more thorough cleaning and confirms the system meets safety standards.
Why does mineral buildup affect tankless systems?
Mineral deposits reduce heat transfer and restrict water flow, which lowers efficiency, causes inconsistent water temperatures, and can shorten the overall lifespan of the unit.
What maintenance keeps water heaters most efficient?
Key maintenance tasks include flushing the system to remove scale, cleaning inlet filters, and inspecting burners or heating elements to maintain optimal efficiency.
When should I call a plumber for tankless water heater issues?
If you notice temperature fluctuations, unusual noises, visible leaks, or have trouble completing maintenance tasks, contacting a professional plumber helps prevent more serious and costly problems.
Trust MNS Plumbing, a licensed and friendly plumber in the Phoenix area, for all your gas water heaters, electric water heaters, and gas line installation and repair needs.
