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Ontario Furnace Red Tag Guide

Furnace Red Tag in Ontario: What It Means and What To Do Next

If your furnace has been red-tagged, the most important thing is to understand the written safety violation before making a repair or replacement decision. This guide explains Type A and Type B red tags, what to do right away, when a second opinion makes sense, and how a red-tagged furnace can be corrected.

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The Quick Answer

What does it mean when a furnace is red-tagged?

A furnace red tag means a technician has identified an unsafe or unacceptable condition with a gas appliance or its installation. The written notice should explain the issue, the appliance involved, and whether the violation is an immediate hazard or a correction that must be completed within a set timeframe.

Do not ignore the notice. If the gas supply has been shut off, do not attempt to restart the appliance or bypass the shutoff. Use a qualified, properly registered contractor to assess and correct the issue.

Start here

  • Read the written safety violation.
  • Confirm whether it is an A or B violation.
  • Do not operate equipment that has been shut down.
  • Request a clear repair or replacement option in writing.

In this guide

What to do first Type A vs Type B Example notice Common causes Cracked heat exchanger Second opinion How a red tag gets cleared FAQ

Immediate Steps

What should you do right after a furnace red tag?

A red tag can feel stressful, especially in the heating season. The best first step is not to panic or approve the most expensive option immediately. Start by confirming what was written on the safety violation form and whether the appliance was shut off.

Do not bypass or restart unsafe equipment

If the furnace has been shut down because of an immediate hazard, do not restart it, relight it, reconnect it, or attempt a temporary workaround. A red tag is a safety matter and should be handled by qualified gas professionals.

1

Read the notice

Check the appliance listed, the defect identified, the violation category, and the correction required.

2

Ask for explanation

A technician should be able to explain the unsafe condition and why repair or replacement is required.

3

Get the options

Request the repair option, replacement option, timeline, and warranty details in writing before deciding.

Ontario Red Tag Types

Type A vs Type B furnace red tag in Ontario

In Ontario, homeowners commonly see red-tag language described as an A violation or a B violation. The difference matters because one is treated as an immediate hazard, while the other gives the homeowner time to correct the issue.

A Violation

Immediate hazard

An A violation means the appliance creates an immediate hazard. The gas supply to the appliance or building is shut off immediately. The equipment should not be operated until the unsafe condition has been corrected.

B Violation

Correction required

A B violation means the appliance is not considered an immediate hazard, but repair or replacement is still required. Enbridge Gas currently states that homeowners have up to 42 days for the correction.

For homeowner guidance, review the current Enbridge Gas safety-violation information .

Example Document

What does a furnace red-tag notice look like?

The written notice is important because it tells you what was identified and what action is required. Keep a photo or copy of the notice so another qualified contractor can review it if you request a second opinion or a repair estimate.

Example of an Ontario gas appliance safety violation notice for a red-tagged furnace
Example of a gas-appliance safety violation notice. Before publishing, use a fully redacted image with all customer, property, technician, and identifying details removed.

Common Causes

Why does a furnace get red-tagged?

A furnace can be red-tagged for several reasons. Some issues are related to the appliance itself, while others involve venting, gas piping, combustion, or installation conditions. The written notice should identify the specific concern.

Cracked or failed heat exchanger

A heat exchanger separates combustion gases from the air moving through the home. Cracks, holes, or severe corrosion can create a serious safety concern.

Carbon-monoxide concern

Unsafe combustion, venting failure, or internal appliance defects can lead to elevated carbon-monoxide risk and should be corrected immediately.

Venting issue

Damaged, disconnected, improperly sloped, blocked, or incorrect venting can prevent combustion products from leaving the home safely.

Gas piping or installation defect

Unsafe gas piping, appliance clearances, missing shutoffs, improper connections, or other installation problems can result in a safety violation.

Failed safety control

Gas furnaces rely on safety controls to prove ignition, airflow, venting, flame, and temperature. Failed safety devices must be taken seriously.

Severe corrosion or deterioration

Internal rust, water damage, or long-term deterioration can make an older furnace unsafe or uneconomical to repair.

Cracked Heat Exchangers

Was your furnace red-tagged because of a cracked heat exchanger?

A cracked or failed heat exchanger is one of the most serious furnace findings. It can also be one of the most expensive repairs, which is why homeowners often need to compare the cost of repair against the cost and warranty of a replacement furnace.

Need the cost breakdown?

Read our related guide: furnace heat exchanger cost in Toronto . It explains repair cost factors, warranty considerations, and when replacement may offer better long-term value.

Real inspection example: severe internal corrosion with a confirmed cracked heat exchanger and elevated carbon-monoxide readings. Every furnace must be assessed individually by a qualified technician.
City Home Comfort technician inspecting a furnace in a Toronto home

Second Opinions

Can you get a second opinion on a furnace red tag?

Yes. A red tag should always be taken seriously, but you can request another qualified contractor to review the written notice, inspect the appliance, and explain the repair or replacement options.

This is especially useful if you were verbally told your furnace was unsafe but did not receive a written safety violation, if the explanation was unclear, or if the proposed repair is expensive and you want to compare options.

  • Keep a copy or photo of the red-tag notice.
  • Do not operate equipment that has been shut down.
  • Ask what defect was found and how it was confirmed.
  • Request repair and replacement options in writing.
  • Use a TSSA-registered fuels contractor .

Correction Process

How does a furnace red tag get cleared?

A red tag is cleared by correcting the unsafe condition, documenting the work, and following the required process for the type of violation. Depending on the situation, that may involve a repair, appliance replacement, gas piping correction, venting correction, or another required safety repair.

1

Confirm the violation

Review the notice and confirm whether it is an immediate A violation or a B violation with a correction deadline.

2

Complete the repair or replacement

The unsafe condition must be corrected by properly qualified professionals. The required work depends on what was written on the notice.

3

Document the correction

Keep records of the work completed, the contractor details, invoice, photos, and any correction form or confirmation required for the violation.

4

Restore safe operation

If gas was shut off, the appliance must not be used until the unsafe condition has been corrected and the required process for safe operation has been followed.

TSSA states that registered fuels contractors are the businesses legally authorized to perform fuels-related work in Ontario. Homeowners can verify contractors through the TSSA registered fuels contractor directory .

Repair or Replacement

Should you repair the issue or replace the furnace?

The answer depends on the defect, the age of the furnace, parts availability, warranty coverage, and the total labour cost. A newer furnace with available parts may be worth repairing. An older furnace with a failed heat exchanger, corrosion, or repeated service issues may be better replaced.

Get both options before deciding

A clear written comparison should include the repair cost, replacement option, equipment warranty, labour warranty, timeline, and what is required to correct the red tag.

Request Red-Tag Help Get a Furnace Replacement Estimate

Prevention

Can maintenance help prevent future red tags?

Maintenance cannot guarantee that a furnace will never fail, but it can identify corrosion, venting problems, combustion issues, airflow restrictions, and worn components before they become a no-heat emergency.

Annual furnace maintenance is especially important for older heating equipment. A fall inspection gives homeowners more time to plan repairs or replacement before the first major cold snap.

Related service: heating system maintenance and furnace tune-up .

Frequently Asked Questions

Furnace red tag questions in Ontario

What does it mean when a furnace is red-tagged?
A red-tagged furnace means a technician identified an unsafe or unacceptable condition with the gas appliance or installation. The written notice should explain the appliance involved, the problem identified, and the correction required.
What is an A violation in Ontario?
An A violation means the appliance creates an immediate hazard. The gas supply to the appliance or building is shut off immediately, and the equipment should not be operated until the unsafe condition has been corrected.
What is a B violation in Ontario?
A B violation means the appliance is not considered an immediate hazard, but repair or replacement is required within the allowed timeframe. Enbridge Gas currently states that homeowners may have up to 42 days.
Can I use my furnace after it has been red-tagged?
Do not operate a furnace that has been shut down because of a safety violation. Read the written notice and contact a qualified, registered contractor to assess and correct the issue.
Can I get a second opinion after a furnace red tag?
Yes. You can ask another qualified contractor to review the written notice, inspect the furnace, explain the finding, and provide repair or replacement options. Do not operate equipment that has been shut down while arranging the second opinion.
Does a red tag always mean I need a new furnace?
Not always. Some safety violations can be corrected with repair. Replacement may make more sense if the furnace is older, the heat exchanger has failed, parts are unavailable, or the repair cost is close to the cost of a new system.
Who can fix a red-tagged furnace in Ontario?
Gas appliance work in Ontario should be handled by properly qualified professionals. TSSA identifies registered fuels contractors as the businesses legally authorized to do fuels-related work in Ontario.
What should I send City Home Comfort for red-tag help?
Send a photo of the red-tag notice, photos of the furnace, the furnace model and serial number if visible, and a short explanation of what the technician told you. This helps us understand the issue and provide the right next step.

Toronto & GTA Furnace Help

Red-tagged furnace? Get a clear repair or replacement path.

Share the details from your notice and compare the next step clearly. City Home Comfort has served Toronto and the Greater Toronto Area since 1981.

Request Red-Tag Help Call (416) 556-8368

Need a replacement estimate?

Upload your furnace photos and submit your details for a fast, no-obligation replacement estimate with suitable equipment options.

Get a Furnace Replacement Estimate

Need heat-exchanger cost details? Read the heat-exchanger cost guide.

This page provides general educational information. Gas appliances must be assessed, repaired, and cleared by qualified professionals in accordance with applicable Ontario requirements.
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