A whirring, grinding, or louder-than-usual fan on a Surrey tankless unit is worth investigating before it leads to a full combustion fan failure.
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Quick answer
Fan noise from a tankless water heater in Surrey is most often caused by worn combustion fan bearings on an older unit, debris pulled into the intake, a restriction somewhere in the intake or exhaust path forcing the fan to work harder, or vibration from a mounting surface transmitting sound through the wall. A technician listens for the specific character of the noise and checks airflow before deciding whether it is a bearing replacement, a cleaning, or a mounting adjustment.
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The combustion fan inside a tankless unit pulls in air for the burner and pushes exhaust out through the venting system, and it runs at a specific speed that the control board adjusts based on firing rate. A healthy fan has a fairly consistent, moderate hum; as bearings wear over years of use, that hum can shift toward a higher-pitched whine, a grinding sound, or an intermittent rattle.
On properties with mature landscaping, common in older parts of Surrey and larger established lots, leaf litter, seed pods, and general yard debris can find their way into an intake if the termination or intake screen is not well maintained, and debris caught in the fan housing itself will produce a distinct rattling or ticking noise as the blades turn.
On units that have been in service many years without any major service, worn bearings are simply a function of age and total run hours, and Surrey's larger household sizes on some properties mean more total hot water cycles per year than a smaller household would put through the same unit, which can accelerate normal wear.
| Noise character | Likely cause |
|---|---|
| Gradual, steady increase in volume over years | Bearing wear from normal aging |
| Rattling or ticking, comes and goes | Debris caught in the fan housing or intake |
| Loud vibration felt through the wall | Mounting hardware loosened over time |
| Sudden onset paired with reduced output | Fan struggling against a new airflow restriction |
A clogged intake or loose mounting hardware is a quick, inexpensive fix. Worn fan bearings usually mean replacing the combustion fan assembly, which is a moderate repair well within the range of routine tankless service on a unit that is otherwise healthy.
On a much older unit already showing other signs of wear, a technician may discuss whether investing in a fan replacement makes sense versus planning for a full replacement in the near term. As a ballpark, not a quote, a new tankless installation in the Surrey area runs $3,500 to $7,500.
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.
On its own it is usually more of an annoyance than an immediate safety issue, but a failing combustion fan can eventually affect proper venting, so it is worth addressing before it progresses to a full failure.
Clearing visible debris from an accessible exterior intake screen is generally fine. Opening the unit's cabinet to inspect or clean the fan itself should be left to a licensed technician.
The fan speed adjusts to match the burner's firing rate, so at higher demand the fan spins faster, and any existing wear or debris issue tends to become more audible at higher speeds.
Many homeowners run a noisy but otherwise functioning unit for a while before scheduling service, but it is best not to let it go indefinitely, since a fan that eventually fails outright will leave you without hot water until it is repaired.
If the reduced output was caused by the fan struggling against a restriction or wearing out, yes. If reduced output has a separate cause like scale, that will need to be addressed independently.
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