The estimate comes before the work
A replacement starts with the size, not the model. A storage tank is matched to the home's first-hour rating and a tankless unit to its flow at the winter temperature rise, which is why the assessment counts fixtures and measures the gas supply before a unit is proposed. CANRO Heating & Cooling states that installation and replacement estimates are free and in writing, so the figure that matters is the written one that follows the visit.
A repair visit is priced differently from a replacement estimate: CANRO states its repair visits carry a diagnostic fee that is credited toward the repair if you proceed. Keeping those two paths distinct matters when the honest answer is repair rather than replacement, and the repair-versus-replace guide walks through that decision separately.
The permit is in place before work begins
Technical Safety BC's homeowner permit page lists installing or replacing all gas appliances, including a water heater, as work that requires a gas permit, and it states the permit must be in place before the work starts. The same page covers replacing gas piping or a vent system, which is what a tank-to-tankless conversion changes.
Which authority issues the permit depends on the address. Technical Safety BC issues it across most of BC, while Vancouver, Richmond, Burnaby, Maple Ridge, the City and District of North Vancouver, and Kelowna issue their own for in-scope single-dwelling work. A licensed contractor normally applies on the homeowner's behalf, and owners of a strata lot, a non-strata duplex, or a home running a business cannot use a homeowner permit at all. The permit path is confirmed before the work is quoted, not after.
Gas and water are shut off, then the old unit comes out
The first physical steps are the safe ones. FortisBC explains that the gas is off when the valve handle is sideways across the pipe, and the cold-water shut-off above the heater stops the water so the tank can be drained. From there the gas connection, the water lines and the venting are disconnected and the old unit is removed.
Everything from the gas valve onward is licensed gas work, and this site publishes no do-it-yourself instructions for gas lines, the gas control, combustion, venting or the relief valve. The permit and the contractor exist precisely because those steps are regulated.
Setting the new unit and reconnecting it
The new heater is set level and reconnected to the water, gas and venting. The venting and combustion air follow the manufacturer's installation manual for the specific model: an atmospheric tank uses its existing chimney or vent, a power-vent or power-direct-vent tank uses the venting its manual specifies, and a condensing tankless unit adds sealed plastic venting and a condensate drain. The gas line is sized to the new input, which is the step that most often changes in a tank-to-tankless conversion.
Two code and safety items belong to this stage. The unit is a flammable-vapour-ignition-resistant design, such as the Flame Guard system on John Wood's atmospheric tanks, and it must be restrained against earthquake movement. FortisBC states that a hot water tank must be securely strapped to keep the water line and gas line from breaking in an earthquake, that the BC Building and Plumbing Codes now require it, and that contractors who install and service water heaters can do it. The earthquake-strapping guide covers that in full.
Commissioning and the inspection
Once the unit is connected, it is filled, purged of air and brought into service per its manual, and the contractor checks the gas connections, the venting and the safety devices. The temperature setting is confirmed against the BC limit of 49 °C at showers and bathtubs, which is why a mixing valve appears on many replacement estimates.
The permit is not closed until the work is inspected. Technical Safety BC requires at least one inspection to be requested within 180 days of the permit being issued, and the inspection confirms the gas connection, the venting, the combustion air and the installation against the manufacturer's instructions. A conversion that adds sealed venting, a condensate drain and a larger gas supply is inspected against the same rules.
What the replacement estimate does and does not cover
The written estimate is the place to see what the job includes, because a like-for-like swap and a conversion are different scopes. A tank-to-tankless conversion adds venting, a condensate path, a 120 V outlet and often a gas supply or meter change, and the tankless-gas-supply guide explains how the meter exchange is arranged through FortisBC when the load requires it.
This site does not publish prices it has not verified. CANRO states that installation and replacement estimates are free and in writing and that repair diagnostics are credited toward the repair, and permit fees are set by the issuing authority. The estimate for the address is the number to work from.