A tankless descaling visit flushes mineral buildup out of the heat exchanger using isolation valves and a circulation pump, restoring lost efficiency.
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Quick answer
A tankless descaling visit uses the unit's built-in isolation valves and a circulation pump to flush a descaling solution through the heat exchanger, dissolving mineral scale that has built up from normal water flow. The technician also checks inlet water filters, confirms venting and combustion are normal, and tests hot water performance after the flush to confirm the fix worked. How often this is needed depends on your local water hardness, with well-water homes generally needing it more often than homes on typical Lower Mainland reservoir water.
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A gas tankless water heater has no storage tank, so it heats water rapidly as it passes through a compact heat exchanger. That intensity of heat transfer is exactly the condition under which dissolved minerals, mainly calcium and magnesium, are most likely to come out of solution and deposit on the exchanger's internal surfaces. Over time this scale layer insulates the exchanger from the water, making the burner work harder for the same output, which is why descaling is treated as its own maintenance item rather than something folded into a general inspection.
Because scale builds gradually, the loss of efficiency is easy to miss day to day. A descaling visit is the point where that slow decline gets identified and reversed before it turns into a flow-restriction fault or a shortened service life for the unit.
Alongside the descaling itself, the technician typically checks the inlet water filter for sediment, inspects the venting for any obstruction, and confirms combustion is normal, since a unit due for descaling is sometimes also overdue for these related checks.
| Water source | Typical scale pace | Descaling frequency |
|---|---|---|
| Metro Vancouver reservoir water | Slower, water is relatively soft | Longer interval, per manufacturer guidance |
| Fraser Valley or private well water | Faster, often harder water | Shorter interval recommended |
Much of the Metro Vancouver core draws on soft reservoir water, which slows scale formation compared to many other regions, but it does not eliminate it. Homes on well water, more common toward the Fraser Valley, typically need more frequent descaling, and a technician can help set a realistic schedule based on your specific water source rather than a generic assumption.
None of these are dramatic on their own, but together they are a reasonable reason to book a descaling visit ahead of the usual schedule rather than waiting.
In most cases a scaled but otherwise healthy tankless unit is a straightforward descaling job, not a repair. Descaling only becomes a bigger conversation if the heat exchanger has gone long enough without service that scale has caused a flow-sensor fault, damaged an internal component, or led to repeated overheating shutdowns. A technician can generally tell from the unit's service history and how it is currently performing which situation you're in before starting any work.
Safety note
Descaling itself does not typically involve gas-side work, but any related combustion, venting, or gas line inspection on a tankless water heater must be done by a Technical Safety BC licensed gas fitter. If you ever smell gas or suspect a carbon monoxide issue, leave the home immediately and call FortisBC at 1-800-663-9911.
The circulation portion alone typically takes under an hour, but with isolation, flushing, and a post-service performance check, plan for a technician to be on site for a reasonable part of a visit.
Some homeowners with the correct isolation valves and a descaling pump kit do this themselves following the manufacturer's instructions, though many prefer to have combustion and venting checked at the same time by a licensed technician.
This depends on your specific water source and usage, with reservoir-fed homes generally needing it less often than well-water homes, and the manufacturer's documentation for your model setting the general guideline.
Efficiency declines gradually, and eventually heavy scale can restrict flow or contribute to overheating-related faults, which may require more than a simple descaling to resolve.
No. Descaling addresses mineral buildup specifically. Reduced performance can also come from gas supply issues, venting problems, or fixture-side restrictions, which a technician checks separately.
Warranty terms are set by each manufacturer and vary, so confirm your certificate for what routine maintenance like descaling is or isn't included in your specific coverage.
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