Descaling flushes mineral buildup out of a tankless water heater's heat exchanger, and while Metro Vancouver's comparatively soft municipal water reduces the pace of scale buildup, it does not eliminate the need for periodic service.
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Quick answer
Descaling a tankless water heater involves circulating a mild acidic solution through the unit's heat exchanger with a small pump to dissolve mineral scale that builds up on internal surfaces over time, which restores heating efficiency and flow. Cost depends on how straightforward the unit's isolation valves are to connect to, whether it is a routine maintenance flush or a unit that has gone many years without service and needs more thorough treatment, and travel to the property. Homes on Metro Vancouver's municipal supply typically need this less often than homes on Fraser Valley well water, but manufacturers still specify periodic descaling regardless of local water hardness.
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Metro Vancouver draws its municipal water mainly from mountain reservoirs, which is comparatively soft compared to groundwater sources, and this does slow the rate of mineral scale formation inside a tankless unit's heat exchanger. It does not stop it entirely, though, because every water supply carries some dissolved minerals, and a tankless heat exchanger's narrow passages and high surface temperature are exactly the conditions where whatever minerals are present tend to precipitate out and deposit over months and years of operation.
A technician connects a small pump to the unit's dedicated isolation valves, which are installed specifically for this purpose during a proper tankless installation, and circulates a descaling solution through the heat exchanger for a set period, then flushes it clean with fresh water before returning the unit to service. Units installed without isolation valves make this process considerably more difficult, sometimes requiring valves to be added before descaling can be done properly, which is worth checking at installation time regardless of which company installs the unit.
| Sign | What it suggests |
|---|---|
| Hot water takes longer to reach temperature than it used to | Scale reducing the heat exchanger's efficiency |
| Unit shows an error pattern documented as a flow or temperature-related fault | Scale restricting internal flow enough to trigger a safety response |
| Noticeable drop in flow rate at fixtures served by the tankless unit | Scale narrowing internal passages |
| It has been longer than the manufacturer's recommended interval since the last service | Preventive descaling is due regardless of visible symptoms |
A unit with properly installed isolation valves in an accessible location is a relatively quick, routine service. A unit installed without isolation valves, or in a cramped location such as a tight closet or crawlspace access point, takes longer and may require additional work to set up proper connection points. A unit that has gone many years without any descaling, especially one on well water in outlying areas, may need a longer treatment cycle or, in more advanced cases, a technician may find scale damage that requires heat exchanger inspection beyond a standard flush.
Homes outside the main municipal supply area, particularly on private wells in parts of the Fraser Valley, often have measurably harder water than Metro Vancouver's reservoir-fed system, and tankless units on well water typically need descaling on a shorter interval. This is worth discussing at installation, since a whole-home water softener or a scale-inhibiting filter ahead of the tankless unit can meaningfully reduce how often descaling is needed on hard well water.
Safety note
If you ever smell gas near the boiler or water heater, or notice unusual soot, staining, or a persistent headache when the appliance is running, leave the home immediately and call FortisBC at 1-800-663-9911 from a safe distance. Do not attempt to relight a pilot, open a gas valve, or work on venting yourself; this work must be done by a Technical Safety BC licensed gas fitter.
Manufacturers typically specify an interval based on water hardness; homes on the region's comparatively soft municipal supply often need it less often than homes on harder well water, but check your specific unit's manual.
Warranty terms are set by each manufacturer and often require documented maintenance including descaling, so it's worth verifying your certificate's specific requirements.
It is possible with a proper kit and isolation valves already installed, but many homeowners prefer a technician who can also inspect the unit's overall condition during the same visit.
Scale gradually reduces heating efficiency and flow, and in more advanced cases can contribute to heat exchanger damage that a simple flush can no longer fully address.
Generally yes; private wells in parts of the Fraser Valley often carry more dissolved minerals than Metro Vancouver's reservoir-fed municipal supply, which speeds up scale buildup.
It means a technician may need to add proper isolation valves before a full descaling can be done efficiently, which is worth addressing rather than skipping maintenance altogether.
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