Outdoor tankless units skip indoor venting entirely but face our coastal weather directly, while indoor units need proper venting but are shielded from the elements.
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Quick answer
An outdoor tankless gas water heater is designed to be mounted on an exterior wall and vents its exhaust directly to open air without indoor ducting, while an indoor tankless unit is installed inside the home, typically in a mechanical room, laundry area, or crawl space, and requires dedicated intake and exhaust venting routed through the wall or roof. Outdoor units save indoor space and simplify venting but are exposed to our damp coastal climate and winter cold snaps, which makes freeze protection and installation location important, while indoor units are more sheltered but require finding suitable mechanical space and a viable vent path. Homes with limited interior mechanical space often lean outdoor, while homes prioritizing weather protection for the equipment often lean indoor.
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An outdoor tankless unit is built with a weatherproof housing and is mounted directly on an exterior wall, drawing combustion air from outside and venting exhaust straight out through the unit itself rather than through a length of indoor ducting. This eliminates the need to find indoor venting clearances entirely, which can be a real advantage in homes with tight mechanical rooms or additions where running new venting through finished ceilings isn't practical.
An indoor tankless unit sits inside the home's building envelope and needs a dedicated intake and exhaust vent run, usually rigid piping through an exterior wall or up through the roof. It's protected from rain, wind, and direct temperature swings, and it's generally easier to access for routine maintenance without going outside in poor weather.
| Factor | Outdoor tankless | Indoor tankless |
|---|---|---|
| Venting | Vents directly through the unit, no indoor ducting | Needs dedicated intake/exhaust venting run |
| Weather exposure | Directly exposed to rain, wind, cold | Sheltered inside the building envelope |
| Freeze considerations | Needs freeze protection features and sheltered placement | Generally lower freeze risk indoors |
| Indoor space used | None | Requires mechanical room or closet space |
| Maintenance access | Outdoors, weather-dependent | Indoors, accessible year-round |
Metro Vancouver's damp climate and occasional hard winter cold snaps make placement of an outdoor unit a real consideration, not just a convenience choice. An exposed exterior wall on the north side of a home, or a spot that catches direct wind off English Bay or the Fraser River, sees more weather stress than a more sheltered wall. A technician will look at wind exposure, eave overhang for rain protection, and how the specific unit's freeze-protection features are designed to hold up during a multi-day cold snap before recommending an outdoor location.
Laneway homes and secondary suites with very little spare interior space often favour outdoor units simply because there's nowhere practical to fit an indoor unit and its venting without giving up usable square footage, while a larger character home with an unfinished basement mechanical room may have plenty of room to accommodate an indoor unit's venting run without difficulty.
As a ballpark, not a quote, a tankless installation in this region generally runs $3,500 to $7,500, with the specific figure depending on gas line upsizing, venting complexity, and how much existing infrastructure a technician can reuse. An outdoor unit can sometimes reduce venting material costs since no indoor duct run is needed, but this isn't guaranteed and depends entirely on the specific home's layout and the assessment a licensed technician does on site.
Safety note
This comparison involves gas-fired heating equipment, venting, and combustion. Any gas line work, venting change, or connection to a gas appliance must be done by a Technical Safety BC licensed gas fitter. If you ever smell gas or suspect a carbon monoxide problem, leave the home immediately and call FortisBC at 1-800-663-9911 from a safe location before doing anything else.
It's a real risk if the unit isn't properly protected or placed in an overly exposed location, which is why installation location, insulation, and the unit's built-in freeze protection all matter in our climate.
Not necessarily; both types are safe when installed correctly by a licensed gas fitter, but indoor units do avoid direct weather exposure, which some homeowners prefer for long-term durability.
It's possible in many cases, but it means re-routing gas lines and water connections to a new exterior location, so it's worth having a technician assess feasibility rather than assuming it's a simple swap.
Not less overall, just different; outdoor units still need annual inspection, and technicians need to check the unit's weatherproofing and any freeze-protection components specifically.
Outdoor units are often chosen for laneway homes given how little spare interior space these structures typically have, though a technician still needs to confirm a suitable, sheltered exterior wall location.
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