Keep the Hot Water Flowing: The Ultimate Guide to Tankless Water Heater Maintenance
- Jacob Plyler
- Aug 4
- 6 min read
If you’ve recently upgraded to a tankless water heater, you already know the perks: endless hot water, lower energy bills, and a whole lot of saved space in your utility room or garage. But there’s a common misconception that because these units don't have a large tank holding water, they don't require any upkeep.
The truth? Tankless water heaters need routine maintenance just as much as traditional units do.
Here at All Hot Water LLC, we want to make sure you get the absolute most out of your investment. Here is everything you need to know about tankless water heater maintenance and why it’s the secret to keeping your hot water flowing for years to come.
The Hidden Enemy: Hard Water and Scale Buildup
The biggest threat to your tankless water heater isn't heavy usage—it’s the water itself. When water is heated, the natural minerals suspended in it (like calcium and magnesium) separate and attach to the heating elements inside your unit. This is known as scale buildup.
Because tankless units heat water rapidly on demand using a highly sensitive heat exchanger, even a small amount of scale can cause massive problems.
Why is Routine Tankless Water Heater Maintenance So Important?
Skipping your annual maintenance can lead to a domino effect of plumbing issues. Here is why staying on top of it is crucial:
Maintains Energy Efficiency: When scale coats the heat exchanger, your unit has to work twice as hard to heat the water to your desired temperature. This spikes your energy bills and defeats the purpose of having a high-efficiency system.
Extends the Lifespan of Your Unit: A well-maintained tankless water heater can last upwards of 20 years! Neglecting it, however, causes the internal components to overwork and burn out prematurely.
Prevents Frustrating Breakdowns: Scale buildup can restrict water flow, leading to low water pressure, lukewarm water, or a total system shutdown right in the middle of your morning shower.
Keeps Your Warranty Valid: Many top manufacturers require proof of annual maintenance by a licensed professional to keep the warranty active. If a part breaks due to scale buildup, you might end up paying out of pocket.
What Does Tankless Maintenance Involve?
When the pros at All Hot Water LLC come out to maintain your system, we perform a comprehensive check-up. The most important step is the system flush. We isolate the unit from your home's water supply and circulate a specialized descaling solution through the heat exchanger for 45 to 60 minutes. This dissolves the mineral buildup and flushes it out of the system.
We also clean out the vital air and water filters, inspect the ignition system, check for proper gas pressure, and ensure there are no hidden leaks.
Follow a simple maintenance schedule
A clear schedule helps prevent small issues from becoming expensive repairs. The exact timing depends on water quality, usage, and manufacturer guidance, but this general plan works for many homes.
Maintenance task | How often to check it | Why it matters |
Inspect the unit for leaks or corrosion | Monthly | Small leaks can damage parts and nearby surfaces |
Check the area around the heater | Monthly | Clear airflow helps the system burn and vent properly |
Clean the inlet water filter | Every few months | A clogged filter can reduce flow and trigger errors |
Inspect venting and intake paths | Every few months | Blockages can affect safety and performance |
Flush and descale the heat exchanger | About once a year | Scale buildup reduces efficiency and water flow |
Schedule professional service | About once a year | A technician can test parts, combustion, and safety controls |
Homes with very hard water may need flushing more than once a year. A water treatment system can also help reduce scale, though it does not replace regular service.
The best maintenance plan is the one that fits the water quality in the home. Hard water changes the schedule.
Check for early warning signs
A tankless water heater usually gives clues before it fails. Catching these signs early can keep the fix simple.
Watch for these changes:
Hot water takes longer than usual to arrive
Water temperature rises and falls during use
The unit shuts off during a shower
The display shows recurring error codes
The water flow seems weaker at hot taps
The heater makes new rattling, clicking, or rumbling sounds
There is moisture, rust, or staining below the unit
Some delay in hot water delivery is normal, especially when the heater is far from the fixture. But a sudden change is worth investigating.
Temperature swings often point to flow issues, scale buildup, dirty filters, or a problem with the gas supply or heating elements. Do not ignore repeated shutdowns. They can signal a venting, combustion, electrical, or internal component issue.
If you smell gas near a gas-fired unit, leave the area and contact the gas utility or emergency service. Do not try to troubleshoot a gas odor yourself.
Signs It’s Time for a Service Call
Not sure when your unit was last serviced? Keep an eye out for these warning signs:
Your water isn't getting as hot as it used to.
You’re experiencing a drop in water pressure.
The system is making unusual rumbling or clicking noises.
Your unit is displaying an error code on the digital screen.
Know when to call a professional
Some maintenance is safe and simple. Other tasks need training, tools, and testing equipment.
Call a licensed professional if you notice:
Repeated error codes
Gas odors
Soot marks or burn marks
Water leaking inside the cabinet
Ignition failure
Loud or unusual noises
No hot water despite normal flow
Damaged venting
Electrical issues
Freezing damage
Annual professional service can include checks that go beyond basic homeowner maintenance. A technician may inspect burners, sensors, wiring, gas pressure, venting, condensate drainage, and safety controls. For condensing tankless units, the condensate neutralizer may also need attention.
Professional service is also useful before heavy-use seasons. If guests are coming for the holidays, or if a rental home will see more occupancy, schedule service before demand increases.
Avoid common maintenance mistakes
Good maintenance keeps the system running well. Poor maintenance can create new problems.
Avoid these mistakes:
Using harsh chemicals not approved by the manufacturer
Skipping the clean-water rinse after descaling
Forgetting to reopen valves after service
Ignoring small leaks
Blocking the intake or exhaust with storage
Setting the temperature too high to compensate for poor performance
Removing panels without knowing what is inside
Resetting error codes repeatedly without fixing the cause
A reset may get hot water running again for a short time, but it does not solve the reason the code appeared. If the same code returns, treat it as a repair issue.
How Often Should It Be Done?
As a general rule of thumb, we recommend having your tankless water heater flushed and serviced annually or at least bi-annually. However, if your home has particularly hard water or if your household uses a massive amount of hot water, you may need a flush every 6 to 9 months.
Make maintenance part of the home routine
Tankless water heaters reward regular attention. Clean water flow, clear venting, correct temperature settings, and annual descaling all help the unit do its job with less strain.
Start with the easy checks. Look for leaks, clean the inlet filter, keep the surrounding area clear, and watch for changes in hot water performance. Then plan an annual or bi-annual flush and professional inspection based on the manual and local water conditions.
A tankless system does not need constant attention. It just needs the right attention at the right time. With a simple routine, the heater can stay efficient, dependable, and ready every time hot water is needed.
Leave it to the Experts at All Hot Water LLC!
While there are DIY tutorials out there, flushing a tankless water heater requires specific valves, a submersible pump, and a deep understanding of the unit's electronics and gas lines. Make it easy on yourself and let the professionals handle it!
Don’t wait until your water goes cold. Protect your investment and ensure you always have access to endless hot water.
Ready to schedule your annual tankless water heater tune-up? Contact All Hot Water LLC today to book your appointment!
864-241-6712
Comments