What Is a Red Tag and a Warning Tag?

Gas‑fired appliances are part of many homes and rental properties across Ontario. Because faulty gas equipment can expose occupants to carbon monoxide (CO) and other hazards, the Technical Standards and Safety Authority (TSSA) – Ontario’s regulator for fuels – requires certified gas technicians to affix warning tags when they discover an unsafe condition. These tags, often called red tags, are a formal notice that the appliance is not compliant with safety standards and that the owner must correct the problem. Here’s what you need to know.

What a Warning Tag Means

A warning tag is attached directly to the appliance and is registered with the local gas utility. It signals that the equipment is unsafe to operate and that action is required. TSSA‑licensed gas technicians are legally obligated to issue a tag when they find a fuel‑burning appliance or related piping that poses a danger. The tag stays with the appliance until the hazard is corrected and a licensed contractor clears the warning with the utility. You cannot simply remove it yourself; doing so could put you and those living in the home at risk.

Type A Tag – Immediate hazard

The Type A tag is the most serious. When an appliance has a confirmed CO leak, gas leak or other critical defect, the gas supply must be shut off right away. The warning tag states that the equipment cannot be used under any circumstances until it has been repaired or replaced by a licensed technician. Utilities like Enbridge or propane suppliers are notified, and only a qualified professional may restore service once the hazard is eliminated. Common reasons for a Type A tag include:

• Cracked heat exchangers that could release deadly CO into the home.
• Major gas leaks or unsafe burner operation.
• Faulty safety controls that prevent the system from shutting down in an emergency.

Type B Tag – Non‑imminent hazard

A Type B tag signals that the appliance has a serious deficiency but does not pose an immediate threat. The equipment may continue operating, but the owner must correct the issue by the expiry date indicated on the tag (often 30–90 days). If the problem isn’t fixed by the deadline, the gas utility will shut off service. Typical Type B issues include rusty heat exchangers, improper installations, venting issues or aging gas lines. This system gives homeowners time to schedule repairs without losing heat while still ensuring dangerous equipment is ultimately addressed.

Why Warning Tags Are Issued

Technicians don’t issue tags lightly. They are protecting occupants from hazards such as:

• Carbon monoxide leaks – CO poisoning causes an estimated 300 deaths and 200 hospitalizations in Canada each year. Because CO has no smell, colour or taste, red tags ensure defective appliances are shut down before the gas can accumulate.
• Gas leaks – Escaping natural gas can lead to fires or explosions. Type A tags require immediate shut‑off; Type B tags cover issues like poor gas pressure or deteriorating piping.
• Ventilation problems – Blocked vents, flues or chimneys can cause fumes or soot to back up into a building.
• Faulty safety controls – Inoperative limit switches or blocked pressure switches can prevent a furnace from shutting down when it overheats.

What to Do if You Receive a Tag

If you receive a warning tag:

1. Take it seriously – Do not attempt to reconnect or operate the equipment yourself. For Type A tags, the gas supply is already shut off; for Type B, it’s best to stop using the appliance until a professional has evaluated it.
2. Call a licensed HVAC professional – You have the right to hire any TSSA‑registered contractor. They will diagnose the issue and tell you whether a repair or replacement is needed. TSSA maintains a searchable directory of certified fuel contractors.
3. Get a second opinion – If you feel unsure about the tag, ask for proof and request another technician to inspect the equipment. ServicePlus Heating and Cooling are always happy to provide a second opinion.
4. Fix the problem – Complete the necessary repairs or replace the appliance. Once the work is done, the contractor will fill in the clearance portion of the tag and submit it to the gas utility. The utility will then clear the warning and restore service.

While no one likes to see a red tag on their furnace or water heater, these warnings play a vital role in keeping buildings safe. Knowing the difference between Type A and Type B tags, acting quickly to fix problems, and working with qualified professionals will protect your home. Regular maintenance and annual inspections are the best way to avoid receiving a warning tag in the first place.