Anthony — TSSA-Certified G1 Gas Technician
TSSA G1 licence #TBD · 15+ years in gas and mechanical trades · Service area: Greater Toronto Area, Ontario
Last updated: 2026-09-01
Why can't a residential HVAC tech clear a commercial red tag?
Because of the input rating. Under Ontario's certification structure, a G2 gas technician is authorized on appliances up to 400,000 BTU/h input. A G1 technician has no input limit and can work on commercial and industrial equipment.
Most residential HVAC technicians hold a G2. That is enough for a furnace or a water heater and not enough for a 750,000 BTU/h rooftop unit, a commercial boiler, or a makeup air unit sized for a kitchen exhaust hood. A G2 who works outside that limit is working outside their certification, and the correction record they produce does not hold up.
If your equipment was tagged and the contractor you normally use has told you they cannot touch it, this is usually why. Ask any technician you call what certification level they hold before they attend.
| Certification | Input limit | Typical scope |
|---|---|---|
| G3 | Restricted, supervised | Apprentice-level work under supervision |
| G2 | Up to 400,000 BTU/h input | Residential furnaces, water heaters, small boilers |
| G1 | No input limit | Commercial and industrial gas equipment of any size |
What commercial equipment gets red tagged most often?
Rooftop units lead the list. They live outdoors, they are inspected less often than anything inside the building, and the failures that get them tagged — cracked heat exchangers, corroded flue collectors, blocked or separated venting, gas train leaks — develop quietly over several seasons.
Commercial boilers get tagged for draft and venting problems, low-water cutoff faults tied to a combustion concern, and gas piping that was extended or re-routed during a building change without being brought to code. Makeup air units get tagged when the interlock with the exhaust system does not prove, when combustion air is short, or when a unit was replaced with one sized to a different exhaust load.
Unit heaters in warehouses and shops are tagged for venting clearance, missing shut-off valves, and hanging or clearance-to-combustibles issues created by racking or a mezzanine built after installation. Process equipment — dryers, ovens, kilns, burners on production lines — is tagged for gas train components, missing safety shut-offs, and piping that was never inspected after a line change.
How fast does a commercial tag get answered?
Response priority is set by what the outage costs you, not by the size of the equipment. A tagged unit heater in an unoccupied storage bay and a tagged rooftop unit over an occupied tenant space are the same job technically and completely different jobs commercially.
Tell us three things when you call: what got tagged, whether the building or a tenant space is currently unusable, and whether anything else in the building shares the same gas line or flue. That determines whether this is a same-day attendance or a scheduled one.
Downtime also changes how the correction is sequenced. Where a full repair needs a part that has to be ordered, there is often an interim step that restores partial capacity legally — isolating one appliance, restoring another, and documenting both. That is decided on site, not over the phone.
What does clearing a commercial tag actually involve?
The defect named on the tag is diagnosed, corrected, and then verified with the tests that apply to that equipment: combustion analysis, draft and spillage testing under worst-case building conditions, gas pressure verification at the appliance under full fire, and a leak test on any piping that was opened.
You get a written correction record naming the defect, the correction, and the verification results. Facility managers should keep that record on file — insurers, landlords and incoming tenants ask for it, and it is the document that proves the equipment was returned to service properly.
Where the correction crosses into another trade — sheet metal, roofing, electrical, refrigeration — the work is coordinated rather than handed off to you as a list of phone calls.
Who is responsible when the building is leased?
That depends on the lease, not on the gas code. In most net leases the tenant carries the equipment serving their space and the landlord carries base building systems, but tagged equipment does not wait for that argument to be settled.
Practically: the party who can authorize the work fastest should authorize it, and the cost allocation gets sorted after the gas is back. Get the correction record either way — it is the evidence both sides will reference.
Frequently asked questions
Can a G2 gas technician clear a commercial red tag?
Only if the appliance is at or under 400,000 BTU/h input. Above that rating the work requires a G1 gas technician. Most commercial rooftop units, boilers and makeup air units are above the G2 limit.
How long does a commercial rooftop unit tag take to clear?
A venting, clearance or gas train component defect is often corrected in a single attendance. A cracked heat exchanger or a failed section on a boiler depends on part availability and can run days to weeks, which is why the diagnosis and the part order happen on the first visit.
Will the utility need to come back to unlock the meter?
If the utility locked the meter itself, yes. If the appliance was isolated at the shut-off, the technician who clears the tag can return it to service directly. You are told which situation applies before work begins.
Do you provide documentation for the building owner or insurer?
Yes. Every cleared tag comes with a written correction record naming the defect, the correction performed, and the verification test results.