Annual boiler maintenance checklist: what a technician checks

Technical Safety BC's information bulletin on annual servicing for gas appliances (B-G5 071019 3, Revision 1, May 19, 2010) opens with the reason: all gas-fired appliances require regular maintenance to operate efficiently and safely, and annual servicing is recommended for all home heating devices regardless of fuel type to prevent fires and carbon monoxide poisoning. The bulletin notes that natural gas, propane, oil and wood appliances that are not operating correctly produce carbon monoxide, and that a Canadian certified carbon monoxide detector is advised for added protection.

That framing is what separates an annual boiler service from a tune-up for comfort. The visit is a documented safety inspection of a machine that burns fuel inside the building, and the checklist is the record of what was checked and measured. The bulletin itself says the completed checklist should be left with the customer — which is the document to keep with the boiler's manual and warranty paperwork.

The bulletin's general gas boiler checklist is the published scope for the appliance itself. It begins with the safety devices: check operation of safety limit controls, check the pressure relief valve, check water pressure and temperature set points, and check the expansion tank. It continues through the controls and mechanicals: check operation of the thermostat, lubricate the circulating pump as required, check the radiant floor temperature control device such as a mixing valve or equivalent, and check pressure switches and the vent blower if applicable.

The combustion and venting section follows: inspect burners and clean if required, examine the vent connector and inspect the venting system, check vent damper operation if applicable, check and adjust the pilot light if applicable, check flame rectification, measure stack (flue) temperature, check gas piping to the boiler, check and adjust manifold gas pressure, clock the appliance to verify correct input, confirm combustion and ventilation air is adequate, check for elevated carbon monoxide levels, inspect the heat exchanger, and check the temperature difference between supply and return piping. The checklist closes with cleaning the equipment interior and exterior and leaving the completed checklist, gas contractor name and number, and gas fitter name and number with the customer.

Natural Resources Canada's guide to maintaining your home heating and cooling system (date modified 2025-06-10) recommends hiring a licensed and insured contractor for annual pre-season check-ups — cooling in the spring, heating in the fall — and lists what a general maintenance check-up should include: checking the smart thermostat settings, tightening electrical connections and measuring voltage and current on motors, lubricating moving parts, checking and inspecting the condensate drain, and checking all controls so the unit starts, runs and shuts off properly.

For winter preparation specifically, NRCan's list adds the gas-side checks: gas connections, gas pressure, burner combustion and heat exchanger, noting that improperly functioning connections, a dirty burner or a cracked heat exchanger can cause the system to operate less safely and efficiently. It also reminds homeowners that filters need regular inspection and cleaning or changing, because a dirty filter can increase energy costs and damage the system.

FortisBC's appliance maintenance page tells homeowners what to expect and what to ask for. It recommends regular maintenance including annual service by a licensed gas contractor, suggests using the utility's online directory to find one who employs certified gas fitters experienced with inspecting all types of gas appliances, and advises asking the contractor to inspect the gas lines that run past the meter while the appliances are being serviced.

On the service content, FortisBC says a contractor should check the safety controls, temperature set points and thermostat operation; check pressure switches and the vent blower if applicable; inspect burners and clean if required; and on older models oil the blower and motor and clean the burner. After the service, FortisBC's instruction is simple: ask your gas contractor for a copy of their completed checklist. The page also lists the signs that mean a call rather than a wait — odours, flu-like symptoms that could be CO exposure, pilot outages, delayed ignition, a yellow or wavering flame, soot or streaks on the appliance or venting, uneven heat, or scorch marks from flame roll-out.

The list below collects the published items into a form that can be printed and kept with the boiler's records. It is the technician's list, not a homeowner's DIY list: every item involves opening the appliance, measuring combustion, or working on gas or electrical components, and all of it belongs to a licensed gas contractor.

The service ends with a document, and the document is the point. File the completed checklist with the boiler's model and serial number, the installation and permit records, and the warranty registration, because that file is what the next service compares against, what a warranty claim asks for, and what a buyer's inspector will want to see. FortisBC's advice to ask for the completed checklist and Technical Safety BC's instruction to leave it with the customer are the same habit from two directions.

For the homeowner-side checks between services — system pressure, visible leaks, clear vent terminals, working CO alarms — the annual boiler maintenance checklist on this site covers the safe tasks and the boundary. Anything involving combustion, the gas train, vent repairs or covers belongs to the technician, and the annual service is how that boundary is kept.