Tankless Water HeaterLeak Repair2026-02-07
Tankless Water Heater Leaking
Tankless leaks usually come from fittings, the isolation valves, or internal components — not a failed tank.
Unlike tank heaters, tankless units don't store water, so leaks are usually from connections or internal parts rather than a burst tank.
Common leak sources
Loose or corroded water connections, the isolation/service valves, the pressure-relief valve, or an internal component such as the heat exchanger can leak. Hard-water scale can also contribute.
What to do
Shut off the water isolation valves and power/gas, then call for repair. Note where the water originates to speed diagnosis.
Key takeaways
- Shut the isolation valves and power/gas
- Most leaks are fittings or valves
- Hard water can stress internal parts
- Note the leak source for the technician
Need help with your tankless water heater?
Licensed, gas-certified technicians serving Greater Vancouver since 1999. CombiBoiler.ca — A division of ROMA Heating Ltd..
Frequently asked questions
More Tankless Water Heater articles
Tankless No Hot Water: CausesNo hot water from a tankless unit can be ignition, gas supply, scale, or an error-code lockout.Tankless Water Heater Error Codes ExplainedTankless error codes point to ignition, flow, venting, or scale issues — here's how to read them.Tankless vs Tank Water HeaterTankless gives endless hot water and saves space; tanks cost less upfront and handle big simultaneous demand simply.Tankless Descaling and Hard WaterAnnual descaling protects tankless performance and prevents scale-related faults in hard water.Tankless Installation Cost in VancouverWhat a tankless water heater costs installed in Greater Vancouver, and what drives the price.The Tankless Cold Water Sandwich ExplainedA brief cold burst between hot draws is the 'cold water sandwich' — and recirculation can fix it.
More from our knowledge base
Furnace Won't Turn On? Causes and FixesFurnaceFurnace Blowing Cold Air: What to CheckFurnaceWhy Your Furnace Short-Cycles (and How to Stop It)FurnaceNo Heat? Emergency Furnace Repair GuideFurnaceFurnace Making Strange Noises: A Sound-by-Sound GuideFurnaceAnnual Furnace Maintenance ChecklistFurnaceAll ArticlesBrowse the full library