What happens during tankless water heater maintenance?
If you own a tankless water heater in Metro Vancouver or the Fraser Valley, annual maintenance is the best way to protect your investment and keep endless hot water flowing. Many homeowners aren’t sure what a technician actually does during a service visit, so it can feel like an unnecessary expense.
In reality, a proper tune-up prevents the two most common tankless failures: mineral scale clogging the heat exchanger and dirty filters starving the burner. Local water carries enough dissolved minerals to matter, especially in valley communities.
HeatLand has serviced tankless units across the Lower Mainland since 1999. Here’s exactly what happens during a professional maintenance appointment so you know what you’re paying for.
Descaling and Flushing the Heat Exchanger
The core of tankless maintenance is descaling, sometimes called a flush. Over time, calcium and magnesium in the water precipitate onto the hot surfaces of the heat exchanger, forming scale that insulates the metal, reduces flow, and forces the burner to run longer. Left unchecked, scale triggers error codes, lukewarm water, and eventually premature failure.
A technician connects hoses to the unit’s service valves and circulates a food-grade descaling solution (often diluted white vinegar or a manufacturer-approved cleaner) through the heat exchanger for 30 to 60 minutes using a small pump. This dissolves the mineral buildup and restores full flow. The system is then flushed with clean water to remove any residue.
If your unit was installed without isolation valves, the technician will recommend adding them, since they make every future flush faster and cheaper. In harder-water pockets of the Fraser Valley, an annual flush is genuinely important rather than optional.
Cleaning Filters and Inspecting Components
Beyond descaling, a full service covers the parts that keep combustion and flow healthy. The cold-water inlet filter is removed, rinsed, and cleared of grit and sediment that can restrict flow and cause temperature swings. On many models there is also an air-intake filter or screen that needs cleaning so the burner gets proper airflow.
The technician inspects the burner assembly and igniter for corrosion or soot, checks the flame sensor, and confirms the unit lights cleanly and modulates correctly. Gas connections are checked for tightness and leaks, and the condensate drain and neutralizer (on condensing units) are inspected and cleared.
Finally, the venting is examined for blockages, proper slope, and secure joints, since a restricted vent is both an efficiency and a safety concern. Any error-code history stored in the control board is reviewed to catch developing problems early.
Testing, Safety Checks, and Documentation
Once cleaning is done, the technician runs the unit through real-world tests: measuring hot-water output temperature, confirming stable flow at multiple fixtures, and checking that the burner modulates without short-cycling. Gas pressure may be verified against the manufacturer’s spec.
Safety verification is a key part of a professional visit. The technician checks for gas leaks at all connections and confirms proper combustion and venting. This is where DIY reaches its limit: if you ever smell gas (rotten-egg odour), suspect carbon monoxide, or see scorching or melting around the vent, shut the unit off and call a licensed gas fitter immediately rather than troubleshooting yourself.
HeatLand technicians are TSBC-certified for gas fitting, licensed, and insured. You’ll receive a summary of what was done and any recommendations, which also helps preserve your manufacturer warranty, since most brands require documented annual maintenance.
Quick Checklist
- Descale/flush the heat exchanger to remove mineral scale
- Clean the cold-water inlet filter
- Clean the air-intake filter or screen
- Inspect burner, igniter, and flame sensor
- Check venting, gas connections, and condensate drain
- Review error-code history and test output temperature
| Maintenance Task | Why It Matters | Typical Frequency |
|---|---|---|
| Descale heat exchanger | Removes scale, restores flow and efficiency | Yearly (more in hard water) |
| Clean inlet filter | Prevents flow restriction and temp swings | Yearly |
| Clean air-intake filter | Ensures proper combustion airflow | Yearly |
| Inspect venting & gas | Safety and efficiency | Yearly |
| Review error codes | Catch faults early | Yearly |
Frequently Asked Questions
How often should a tankless water heater be serviced?
Most manufacturers recommend professional maintenance once a year. In hard-water areas of Metro Vancouver and the Fraser Valley, annual descaling is especially important because minerals build up faster. Some households with very hard water or heavy hot-water use benefit from service every 9 to 12 months to stay ahead of scale.
Can I flush my tankless water heater myself?
Homeowners with isolation valves and a flush kit can descale a unit, but a professional visit also covers gas connections, combustion, venting, and error diagnostics that require training and equipment. Anything involving gas, venting, or suspected leaks should be left to a licensed, TSBC-certified technician for safety.
How long does tankless maintenance take?
A typical annual service takes about 45 to 90 minutes. Descaling alone runs 30 to 60 minutes while the solution circulates, and the rest of the time covers filter cleaning, inspections, and testing. Units without isolation valves take longer because the technician must set up temporary connections.
Does maintenance affect my warranty?
Yes. Most tankless manufacturers require documented annual maintenance to keep the warranty valid. Skipping service and then filing a scale-related claim can lead to denial. Keeping a service record from a licensed contractor like HeatLand protects both the equipment and your coverage.
Reviewed by the HeatLand Heating & Cooling team — licensed HVAC contractor serving Metro Vancouver & the Fraser Valley since 1999. This article is for general guidance only. If you smell gas, suspect a carbon monoxide leak, or are unsure about any electrical or gas component, stop troubleshooting immediately and call a licensed technician or 911.