The Technical Standards and Safety Authority (TSSA) published Gaseous Fuels Code Adoption Document Amendment FS-279-26 on April 2, 2026. It adopts the 2025 edition of CSA B149.1, the natural gas and propane installation code, with Ontario-specific amendments, and it took effect on June 1, 2026. For boiler contractors, the amendments to clause 7.1 are the part worth reading line by line.
What TSSA published
The short answer: a full replacement of Ontario's gaseous fuels code adoption document, not a patch.
The amendment revokes every section of the earlier document and replaces it. According to its background section, it supersedes FS-225-21 from May 2021 and makes five significant changes:
- adoption of CSA B149.1 (2025) with Ontario amendments
- adoption of CSA B149.3 (2025), the field approval code for fuel-related components, with Ontario amendments
- adoption of Annex J of CSA B149.3 for mobile food service equipment, replacing TSSA's own code for that equipment
- adoption of CSA B149.6 (2025) for biogas, replacing the older TSSA digester, landfill and biogas code
- adoption of NFPA 160 (2021) for flame effects before an audience
The document also adds CSA 6.19-17, the residential carbon monoxide alarm standard, to the list of referenced publications.
The boiler clauses, in plain language
TSSA's amendments add clauses 7.1.4 to 7.1.13 to the code. We summarise them here; the exact wording is in the PDF and is what counts.
- Low-water cut-offs on steam boilers. A steam boiler that isn't under continuous attendance by a certified operator needs a dedicated low-water fuel cut-off that can be tested under operating conditions.
- Low-water cut-offs on hot-water heating boilers. An automatically fired hot-water boiler needs one when its input exceeds 120 kW (400,000 Btu/h), or when parts of the circulating system sit below the boiler's lowest safe water level.
- Exemptions with a catch. Piping within 2 m of the boiler, residential combo fan coil units and in-floor heating are excluded from that "below the boiler" test, but a boiler relying on the exemption needs an integral flow-sensing device that shuts off fuel when circulation stops.
- Coil-type and multiple boilers. Larger coil or water-tube boilers that need forced circulation use a flow-sensing device in place of a low-water cut-off, and multi-boiler fin-tube systems can use one header cut-off plus a flow switch on each boiler.
- Relief valve discharge. On boilers of 400,000 Btu/h or less, the discharge pipe must match the valve outlet size and end no more than 300 mm above the floor.
- New and replacement residential boilers under 300,000 Btu/h. These must be direct vent, or meet a list of conditions if they are natural-draft units: same location as the boiler replaced, an isolated boiler room with self-closing doors, outdoor combustion air, and CO alarms by each sleeping area.
The heating-season CO check
The clause that will touch the most service calls is the mandatory safety check for natural-draft boilers with a draft control device, up to 300,000 Btu/h, in one- and two-family homes.
Between October 15 and April 30, a certified G1, G2, G3 or GUT technician who enters such a home for service, maintenance or an emergency must check for that type of boiler. Unless a valid inspection tag is already on it, the technician gives the owner an information sheet, takes a flue-gas CO reading upstream of the draft control, inspects for spillage, and confirms CO alarms are in place. A reading above 100 ppm is treated as an immediate hazard. A boiler that passes gets a tag that expires on May 1.
Analysis: what this means for a boiler company's business
This section is our analysis, not part of the TSSA document.
The heating-season check turns an ordinary service visit into a documented safety inspection, so expect homeowners to ask what it is and why they're being shown a form. Companies that explain it calmly, on the phone and on their website, will look more professional than companies that surprise people with it.
There are three practical marketing steps:
- Update your service pages. If your site still describes Ontario boiler work in terms of the 2021 document, it is out of date. A short, dated explainer page builds trust; our regulation content service is built for exactly this.
- Prepare your CSRs. Write a two-sentence answer for "why is the tech testing my boiler?" and keep it at the phone.
- Price the extra time honestly. If the check adds minutes to a call, decide how you will show that on an invoice before the first customer asks.
None of this replaces reading the document. Confirm anything that affects an installation with TSSA directly.
Where this sits in our coverage
This is one of several Ontario stories on BoilerNews.ca. See our report on TSSA's revision to the boilers and pressure vessels code adoption document, the 2026 inspection certificate fee change, and the Ontario region page for regulators and programs. Alberta brought the same 2025 B149 codes into force three months earlier; our Alberta gas codes story explains how its timing rule works.
BoilerNews.ca reports on the boiler trade; we are a marketing and business consulting service, not a gas contractor, and we don't install or service equipment.
Frequently asked questions
When did FS-279-26 take effect?
The document states an effective date of June 1, 2026. It replaces FS-225-21, the previous gaseous fuels code adoption document, which was dated May 1, 2021.
Does this change apply outside Ontario?
No. A code adoption document is how TSSA tells Ontario industry which codes apply and with which Ontario amendments. Other provinces adopt CSA B149.1-25 on their own schedules and with their own variations.
Is this article compliance advice?
No. It summarises a public TSSA document. Questions about how a clause applies to a specific installation belong with TSSA or a qualified professional.
Where can I read the full amendment?
TSSA publishes FS-279-26 as a PDF on its website. The boiler clauses discussed here sit in the section amending clause 7.1 of CSA B149.1-25.