Richmond's municipal water is generally soft, but tankless units on well or irrigation-fed supply, or units overdue for a flush, still scale up and lose output over time.
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Quick answer
Scale buildup in a Richmond tankless water heater usually shows up as reduced flow, a unit that runs hotter than the set temperature, or a fault shutdown after several years without a descaling flush. Metro Vancouver's municipal water is comparatively soft, so scale accumulates slower here than in hard-water regions, but it still narrows the heat exchanger passages over years of use, especially in homes with higher household demand or an unflushed unit. An annual isolator-valve flush is the standard preventive fix; a badly scaled exchanger sometimes needs professional descaling or, in older units, replacement of the heat exchanger.
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A tankless water heater heats water on demand by running it through a narrow, finned copper or stainless heat exchanger positioned directly over the burner. Every time water passes through, it leaves behind a microscopic trace of dissolved calcium and magnesium. On its own that trace is nothing, but multiplied across thousands of showers, dishwasher cycles, and laundry loads over several years, it hardens into a chalky scale coating on the inside of those narrow passages.
Because the passages in a tankless heat exchanger are much smaller in diameter than the tank in a conventional water heater, even a thin scale layer has an outsized effect. It insulates the metal from the water it is supposed to be heating, forcing the burner to work harder and longer to reach the same setpoint, and it physically narrows the channel the water flows through.
Richmond sits on the Fraser River delta and draws its municipal supply from the regional system, which is comparatively soft compared with well-fed communities further out in the Fraser Valley. That soft water is one of the reasons tankless units in Richmond generally scale slower than units running on well water. It does not mean scale never happens, only that it happens on a longer timeline.
Where CANRO techs do see accelerated scaling in Richmond is in homes with a secondary well or irrigation connection feeding an outbuilding or laneway suite, in older homes where a softener or filter was removed and never replaced, and in any household running a high volume of hot water through a unit that has never been flushed since installation. Richmond's high water table and flood-plain construction also mean a lot of tankless units live in crawlspaces or garages, and access for a routine flush gets skipped simply because the unit is out of sight.
| Factor | Effect on scale rate |
|---|---|
| Municipal soft water (typical Richmond) | Slower scale accumulation, still occurs over years |
| Private well or irrigation cross-feed | Faster scale accumulation, higher mineral content |
| No annual flush since install | Scale compounds year over year regardless of source water |
| High household hot water demand | More total gallons through the exchanger, more mineral deposit |
A proper diagnostic starts before the cabinet ever comes off. A technician reviews how long it has been since the last descaling, asks about any change in flow or temperature the homeowner has noticed, and checks the unit's fault history on the controller if the model logs one.
If the unit was never installed with isolator valves, adding them is usually the first recommendation, because they are what make an annual flush a routine, affordable maintenance visit instead of a major teardown.
Homeowners can do a few useful checks before calling for service. None of these involve opening the gas or venting side of the unit.
Most scale problems caught within the first several years respond well to a standard flush using isolator valves, a small pump, and a descaling solution circulated through the unit for roughly an hour. This is routine, affordable maintenance and the single best thing a homeowner can schedule to extend a tankless unit's working life.
If scale has gone unaddressed for many years, the heat exchanger itself can become permanently restricted or corroded, and a flush may only partially restore performance. At that point the choice is between a heat exchanger replacement, if the manufacturer still supports the model and parts are available, or replacing the whole unit. As a ballpark, not a quote, a new tankless installation in the region typically runs $3,500 to $7,500 depending on venting, gas line sizing, and access; a licensed tech can give you an accurate number after seeing the install.
Safety note
If you ever smell gas (a sulphur or rotten-egg odour) near the tankless unit, hear hissing at a fitting, or the unit's exhaust is spilling into the mechanical room instead of venting outside, leave the home and call FortisBC's emergency line at 1-800-663-9911 from a safe distance before doing anything else. Do not try to relight the unit, reset the breaker, or open the cabinet yourself. Combustion and venting faults on a gas appliance are a Technical Safety BC licensed gas fitter's job, not a DIY project, because they involve flammable gas and carbon monoxide risk.
Once a year is the standard recommendation for most households, though homes on well or irrigation-fed water, or with heavier hot water use, may benefit from flushing every six to nine months. Your installer can set an interval based on your actual water source.
If isolator valves and hose bibs are already installed, a comfortable DIYer can circulate a descaling solution, but confirming the unit is properly isolated, that the pump direction matches the manufacturer's diagram, and that everything is reconnected correctly is worth having a licensed tech do at least the first time.
No. Soft water slows scale buildup, it does not stop it, and skipping flushes for many years still leads to reduced flow, hot spots on the exchanger, and a shorter unit lifespan.
Rattling or popping during firing is a common scale symptom because trapped scale flakes and steam pockets can knock against the exchanger walls, but a technician should confirm that before assuming, since venting or burner issues can produce similar noise.
Only if the low pressure is caused by scale inside the unit itself. If it affects fixtures elsewhere in the home too, or happens even when the tankless unit is off, the cause is more likely elsewhere in the plumbing and a flush will not resolve it.
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