At a minimum, schedule professional maintenance for your tankless water heater at least once a year. In areas with hard water, service may be required every 6 to 12 months. Routine care, such as flushing the heat exchanger, cleaning filters, and inspecting connections, keeps your system efficient, protects the warranty, and extends its lifespan.
Key Takeaways
- Schedule maintenance once every 12 months (or more often with hard water).
- Skipping maintenance may void the warranty and shorten the lifespan.
- Condensing models require special attention to condensate drains and neutralizers.
- Many error codes and leaks are signals that service is overdue.
Why Tankless Water Heater Maintenance Matters
Tankless water heaters are popular because they deliver hot water on demand, take up less space, and are more energy efficient than traditional tanks. But “energy efficient” doesn’t mean “maintenance-free.”
Over time, minerals from your water supply (especially calcium and magnesium) can accumulate inside the heat exchanger, a process called scaling. If left unchecked, scaling can:
- Reduce efficiency: The system works harder to heat water, consuming more energy.
- Lower performance: You may notice lukewarm showers, fluctuating flow, or error messages.
- Increase repair risk: Skipping maintenance raises repair risks. Common issues include ignition failure, faulty sensors, and clogged lines.
- Shorten lifespan: With regular care, tankless heaters can last 20+ years; without it, they may fail in less than 10.
- Void warranty coverage: Most manufacturers clearly state that neglecting maintenance can void warranty claims.
Think of annual maintenance as an insurance policy: it keeps your investment protected and performing at its best.
Tankless Water Heater Maintenance Schedule at a Glance
Here’s a quick reference chart you can use year-round:
| Task | Who Performs | Standard Water | Hard Water | Condensing Model Notes |
| Flush & Descale Heat Exchanger | Licensed Technician | Every 12 months | Every 6–12 months | Check neutralizer & condensate trap |
| Clean Inlet Screen & Air Filter | Homeowner | Every 6–12 months | Every 3–6 months | – |
| Inspect Pressure Relief, Gas & Venting | Licensed Technician | Every 12 months | Every 12 months | Ensure vent slope & seals |
| Check Condensate Line/Trap | Licensed Technician | – | – | Every 12 months |
This schedule provides a clear division between what you can do yourself and what requires professional tankless water heater maintenance.
Annual Homeowner Tasks
While a professional handles most of the heavy lifting, there are simple things you can do to keep your unit in good shape between visits:
1. Clean the Air Intake Filter
- Remove the filter (usually behind a panel).
- Rinse with warm water and mild soap.
- Let it dry completely before reinstalling.
- Repeat every 6–12 months, or more often if your home has pets or dust.
2. Inspect for Leaks or Moisture
- Check underneath the unit for puddles.
- Run your hand along visible pipes to detect dampness.
- Look at valves and connections tighten if needed.
3. Monitor the Display Panel
- If your unit displays error codes, jot them down.
- Occasional codes can be reset, but recurring ones require professional service.
4. Test Water Flow
- Turn on hot water at multiple faucets.
- Watch for inconsistent temperature or reduced flow.
- Early detection can prevent bigger issues.
Professional Service Checklist
An annual tankless water heater maintenance full-service should be handled by a qualified plumber or water heater expert. This typically includes:
- Flushing/Descaling: Connecting a pump to circulate vinegar or a cleaning solution through the heater. This dissolves mineral buildup inside the heat exchanger.
- Water & Air Filter Check: Cleaning or replacing filters to ensure smooth operation.
- Gas Pressure & Burner Inspection: Confirming safe combustion and energy efficiency.
- Vent & Exhaust Review: Ensuring no blockages, leaks, or unsafe conditions.
- Condensate System Maintenance (for condensing units): Cleaning the condensate trap and replacing neutralizer media if it’s saturated.
- Electrical & Safety Check: Inspecting sensors, wiring, and control boards.
- Warranty Documentation: Recording the service to keep your coverage valid.
Professional service not only prevents issues but also gives you peace of mind that your system is operating safely.
Hard Water Adjustments
Water quality has a huge impact on your tankless water heater maintenance schedule.
- Standard water (0–7 grains per gallon): Flush once per year.
- Hard water (8–14 gpg): Flush every 6–12 months.
- Very hard water (15+ gpg): Strongly consider adding a water softener.
How to Know if You Have Hard Water
- White chalky deposits on faucets or showerheads.
- Soap that doesn’t lather well.
- Frequent scale buildup in kettles or coffee makers.
Why It Matters
Hard water accelerates scale formation inside your water heater. Without more frequent maintenance, you’ll see efficiency losses, higher utility bills, and potential early failure of the heat exchanger.
Condensing vs. Non-Condensing Units
Understanding your system type helps tailor your maintenance plan.
Non-Condensing Units
- Exhaust gases exit directly through venting.
- Maintenance focuses mainly on flushing and filter cleaning.
Condensing Units
- Capture additional heat from exhaust gases, which creates condensate.
- Require extra care:
- Condensate Trap Cleaning: Prevents clogs that cause water leaks.
- Neutralizer Replacement: Prevents acidic water from corroding drains.
- Venting Slope Checks: Ensures proper drainage of condensation through PVC pipes.
- Condensate Trap Cleaning: Prevents clogs that cause water leaks.
Failing to service the condensate system can lead to hidden leaks and damage over time.
Common Tankless Water Heater Error Codes
Error codes can feel overwhelming, but they’re designed to point you toward the issue. Here are some of the most common:
| Code | Meaning | What It Usually Means | Action |
| LC | Scale buildup | Heat exchanger coated with minerals | Flush system, call technician if unresolved |
| Ignition Error | Ignition/flame failure | Gas supply, air intake, or venting issue | Professional inspection required |
| Overheat Warning | Water too hot | Flow restriction or thermostat issue | Shut down and call a technician |
| Communication Fault | Internal control board error | Wiring or sensor problem | Reset system, call for service if repeated |
If an error persists after a reset, schedule professional maintenance.
Tankless Water Heater Leaking? What to Do Next
Not all leaks are created equal. Here’s how to interpret them:
Condensation Drips (Normal)
Condensing units naturally produce water vapor. Small drips from the condensate line may be completely normal.
Drips from Valves or Connections
Likely a loose fitting or worn washer. Usually a quick fix.
Continuous Leak from the Unit
May indicate a clogged condensate trap or cracked heat exchanger both require immediate professional service.
Tip: If you can’t identify the source, turn off the unit and water supply, then call for same-day service.
Cost & Time of Maintenance
Homeowners often worry about the price of upkeep. Fortunately, routine maintenance is affordable compared to replacement costs.
- Professional Annual Service: $120–$200 on average.
- DIY Flush Kit: $50–$80 (use with caution if under warranty).
- Time Required: 1–2 hours per service call.
Compare that to the cost of replacement $1,500 to $4,500 and it’s easy to see why maintenance is the smarter choice.
Frequently Asked Questions
- How often should I flush my tankless water heater?
At least once a year, or more often if you live in a hard-water area. - Does skipping maintenance really void the warranty?
Yes. Most warranties require documented maintenance to remain valid. - Can I perform maintenance myself?
Homeowners can clean filters and monitor the system. Flushing and full inspections should be left to licensed professionals. - How long will my tankless water heater last with proper care?
20+ years is possible with regular maintenance and water quality management. - What are the first signs that service is overdue?
Lukewarm water, fluctuating temperature, strange noises, recurring error codes, or reduced water flow. - Final Thoughts & Call to Action
Tankless water heaters are efficient, compact, and long-lasting but only if you take care of them. Following a regular maintenance schedule is the best way to keep your system running smoothly, protect your warranty, and avoid costly surprises.
Don’t wait until you see an error code or a puddle under your unit. A simple annual service appointment can keep your hot water reliable year-round.
Contact Fields & Fowler today to schedule your tankless water heater maintenance. Our team will ensure your system is clean, efficient, and ready to serve your home for years to come.