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: 2026-08-03
What does a Type A tag mean?
A Type A tag is issued when a technician finds an immediate hazard to life or property. The gas supply to that appliance is shut off at the time of inspection, and the appliance cannot be lit or used again until a TSSA-certified gas technician corrects the defect and clears the tag. This is the category used for cracked heat exchangers, active gas leaks, flue gas spillage into occupied space, and blocked venting.
Under CSA B149.1, the standard that governs installation and inspection of gas appliances in Canada, an immediate hazard is one that could reasonably be expected to cause injury or property damage before a normal repair could be arranged. There is no grace period. The technician disconnects or caps the supply, tags the appliance, and the household is without that appliance — heat, hot water, or cooking — until the correction happens.
What does a Type B tag mean?
A Type B tag flags a deficiency that does not present an immediate hazard but still needs to be corrected. The appliance is left running, and the technician documents the defect along with a time frame for correction, which is commonly 30 days but is set case by case based on the nature of the issue.
Typical Type B findings include a missing appliance shut-off valve within reach of the appliance, absence of a drip leg on a gas line, minor clearance-to-combustible issues, or a vent connector that is undersized but not currently spilling. These are conditions that should be fixed properly but do not require shutting down the household's heat or hot water while that happens.
Type A vs Type B: side-by-side comparison
The practical differences come down to whether gas keeps flowing, how much time you have, and what happens if nothing is done.
| Type A | Type B | |
|---|---|---|
| Hazard level | Immediate hazard to life or property | Deficiency, not an immediate hazard |
| Appliance status | Shut off on the spot, cannot be used | Continues to operate |
| Gas supply | Capped or disconnected at the appliance | Left connected |
| Deadline to correct | None — must be corrected before use resumes | Typically 30 days, set by the technician |
| Who can clear it | Certified gas technician only | Certified gas technician only |
| Typical causes | Cracked heat exchanger, gas leak, flue spillage, blocked vent | Missing shut-off valve, no drip leg, minor clearance issue |
Can I keep using the appliance with a Type B tag?
Yes, a Type B tag does not shut off the appliance, so it stays in service while you arrange a correction within the stated time frame. That said, waiting past the deadline without action is not a good idea — the deficiency was noted for a reason, and an insurer or a subsequent inspector who finds an overdue Type B tag will treat it as a red flag during a claim or a sale.
If the deficiency is on a rental appliance, such as a water heater, the correction is still your responsibility as the property owner unless the rental agreement states otherwise for that specific component.
How do I get either tag cleared?
Both tag types are cleared the same way: a TSSA-certified gas technician inspects the corrected work, confirms the defect is resolved, and signs off. There is no self-certification and no way to legally remove either tag yourself.
- Contact a certified gas technician and describe the tag type and appliance
- Send photos of the tag, the appliance data plate, and the affected area
- Get a typical price range before the visit where possible
- Have the defect corrected and tested — leak test, combustion analysis, and draft check as applicable
- Receive documentation that the tag is cleared, which you should keep for insurance or resale records
Does a Type A tag mean the appliance is condemned?
Not necessarily. Many Type A conditions, such as flue gas spillage or a corrected gas leak, are fixable without replacing the appliance. The exception is a cracked heat exchanger, which is treated as an immediate hazard and virtually always means replacement rather than repair, since the crack cannot be safely patched.
Frequently asked questions
Is a Type A tag worse than a Type B tag?
Yes. A Type A tag means the appliance was shut off on the spot due to an immediate hazard, while a Type B tag leaves the appliance running with a deadline to fix a lesser deficiency. Both require a certified gas technician to clear, but only Type A stops you from using the appliance right away.
Who decides which tag type applies?
The inspecting gas technician makes that determination on site, based on the nature of the defect and whether it presents an immediate hazard under CSA B149.1. It is not a choice the homeowner or the utility makes.
Can I ignore a Type B tag if the appliance still works fine?
You can technically continue using the appliance, but the deficiency was documented for a safety reason and typically has a correction deadline of around 30 days. Letting it lapse can complicate insurance claims and will surface again at resale or during any future inspection.
What happens if I use an appliance with a Type A tag anyway?
The gas supply to that appliance is physically shut off or capped, so in most cases it cannot be used without someone illegally reconnecting it. Doing so is a safety violation and would void insurance coverage related to any incident involving that appliance.
Does the tag type affect the cost to clear it?
Not directly — cost depends on the specific defect, not the tag letter. A Type B missing shut-off valve is usually inexpensive to correct, while a Type A cracked heat exchanger usually means the cost of a full appliance replacement.