Signs your tankless water heater needs service
A tankless water heater usually gives warning before it fails outright. Catching these signs early keeps repairs small and avoids a cold-shower emergency.
For Metro Vancouver and Fraser Valley homeowners, most service needs trace back to scale buildup, clogged filters, or ageing components, all of which are manageable when addressed promptly.
Below, HeatLand outlines the clearest signals that your unit needs professional attention, plus the few checks you can safely do yourself before calling a licensed technician.
Performance warning signs
The most common signals are about how the unit performs day to day. Fluctuating or gradually dropping water temperature often points to scale on the heat exchanger or a flow-sensor issue. Reduced hot-water flow, where the same tap delivers less than it used to, may indicate a clogged inlet filter or mineral buildup restricting passages. Longer-than-usual waits for hot water can also flag a developing problem. If the unit struggles to keep up with normal household demand it previously handled, something has changed. These issues rarely fix themselves and tend to worsen. A service visit typically includes descaling, cleaning the inlet filter, and checking sensors and the burner. Addressing performance drops early restores comfort and prevents strain on other components. If you notice these signs, book a professional maintenance visit rather than waiting for a full failure.
Error codes, noises, and water quality
Modern tankless units display error codes that pinpoint problems, from ignition faults to overheating or airflow issues. A code that returns after resetting the unit is a clear service signal; note the code and share it with your technician. Unusual noises such as rumbling, clicking, or whistling often indicate scale, combustion issues, or airflow restriction. Water quality matters too: rusty, discoloured, or metallic-smelling hot water can signal internal corrosion or sediment and should be checked promptly. A rotten-egg smell may point to bacteria or other issues worth investigating. None of these should be ignored. While a single reset is reasonable for an occasional code, repeated codes, persistent noises, or changing water quality mean the unit needs a qualified inspection. A licensed technician can read the diagnostics, identify the root cause, and correct it before it escalates.
Safety signs that need immediate attention
Some symptoms go beyond routine service and require urgent, professional help. If you smell gas near the unit, do not operate switches or the heater; leave the area, ensure ventilation if safe, and call your gas utility and a licensed, TSBC-certified technician immediately. Signs of a carbon monoxide concern, such as unexplained headaches or a CO alarm, warrant leaving the home and calling emergency services. Visible water leaks around the unit can cause damage and may signal a failing connection or internal fault, so shut off water if needed and arrange prompt service. Scorch marks, soot, or a yellow rather than blue burner flame indicate combustion problems that need immediate attention. These are never DIY situations. HeatLand offers emergency service and licensed, insured technicians who can respond safely. When in doubt about a gas, combustion, or water hazard, stop and call a professional.
Quick Checklist
- Note any recurring error codes to share with your technician
- Check for reduced flow, longer waits, or dropping temperature
- Listen for rumbling, clicking, or whistling noises
- Watch for rusty, discoloured, or foul-smelling hot water
- Inspect for leaks, soot, or scorch marks around the unit
- Call immediately for gas smell, CO concerns, or combustion issues
| Sign | Likely Cause | Action |
|---|---|---|
| Fluctuating temperature | Scale or sensor issue | Book service, likely descaling |
| Reduced flow | Clogged filter or scale | Clean filter, descale |
| Recurring error code | Component or airflow fault | Professional diagnosis |
| Gas smell | Gas leak | Leave, call utility and technician now |
Frequently Asked Questions
How often do tankless water heaters need service?
Most manufacturers recommend professional service about once a year, mainly to descale the heat exchanger and clean the inlet filter. Homes with harder water or heavy use may benefit from more frequent visits. Regular service prevents most performance problems and extends the life of the unit.
Can I reset a tankless error code myself?
A single reset for an occasional code is reasonable and often clears it. However, if the same code returns, that is a service signal. Note the code and have a licensed technician diagnose it, since recurring codes usually indicate scale, airflow, ignition, or component issues that need proper correction.
Is discoloured hot water dangerous?
Rusty or discoloured hot water suggests corrosion or sediment and should be checked promptly, though it is not usually an immediate hazard. A rotten-egg smell may indicate bacteria. Either way, have a licensed technician inspect the unit to identify the source and prevent further deterioration.
What should I do if I smell gas near the heater?
Treat it as an emergency. Do not operate switches, the heater, or anything that could spark. Leave the area, and from a safe location call your gas utility and a licensed, TSBC-certified technician. HeatLand offers emergency service for these situations. Never attempt to locate or repair a gas leak yourself.
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.