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Heating · Independent DiagnosisFurnace Second Opinion
A furnace second opinion is a diagnostic visit, $90–$150, in which a TSSA-licensed technician re-tests a furnace that another company has condemned and hands you the evidence: camera photos of the heat exchanger, written combustion-analysis readings and a plain repair-or-replace recommendation. Get one whenever you are told the furnace must be replaced today and nobody has shown you the crack. If the first diagnosis was right, we say so; if it was not, you have numbers to hold against the quote.
The diagnosis that most needs checking is 'cracked heat exchanger'. It is a real failure, it is dangerous when true, and it is also the easiest thing to claim because the homeowner cannot see inside the cells. A proper finding comes with a picture: an inspection camera fed through the burner openings or the blower compartment shows the crack, the rust-through or the clean metal. Ask the first company for that image before you ask anyone for a second opinion.
Combustion numbers back up the camera. With an analyzer probe in the flue we record oxygen, carbon monoxide and flue temperature, then watch what happens when the blower starts: on a breached heat exchanger, blower air pushes into the combustion side and the oxygen reading shifts or the flame wavers. Steady readings and a steady flame through the blower start point away from a breach. Those readings are written on your invoice, so the recommendation is not one technician's word against another's.
Ontario banned unsolicited door-to-door sales of furnaces, air conditioners, water heaters and several related products on March 1, 2018. A company can sign you to a furnace contract in your home only if you contacted it and invited it there for that purpose, a contract that breaks the rule is void, and contracts signed at home carry a 10-day cooling-off period in which you can cancel without giving a reason. Ten days is long enough to get a second set of readings. The steps are in cancelling a door-to-door HVAC contract in Ontario.
A second opinion ends one of three ways. The furnace is sound and needs an ordinary repair, commonly $150–$800; the heat exchanger has failed and replacing it runs $1,500–$3,000, which on a furnace past 15 years is better put toward a new unit; or the defect is real and the furnace should stay off. In every case you leave with photos and readings, and any work you approve goes through our regular furnace repair service at the written price.
Get a second opinion when
- You were told the heat exchanger is cracked but were not shown a photo or a camera image of it
- The 'must replace today' verdict came out of a low-priced tune-up or a free inspection you did not ask for
- The quote expires the same day, or a rental or financing contract appeared before any test results did
- The furnace is under 12 years old and had no symptoms — no CO alarm, no shutdowns, no soot
- A warning tag was issued and you want the defect confirmed independently before spending on it
How it works
The invoice, the quote and any tag left on the furnace tell us what was claimed. If a warning tag is on the appliance, leave it in place and leave the gas off; we test the furnace as found.
The technician inspects the heat exchanger with a camera, runs a combustion analysis where the furnace can be fired safely, and checks the venting, the flame pattern and the rollout and limit switches. An unsafe furnace is not fired just to produce a reading.
You get the photos, the readings and a one-line recommendation: repair, replace or leave alone. Hold it against the first quote line by line, and book the visit here when you are ready.
Common questions
What if you find the same crack the first company did?
Then the first diagnosis stands and we tell you so, with the photo. A licensed gas technician who confirms an unsafe condition is obliged to tag the appliance too, so a second opinion cannot be used to get a dangerous furnace relit. What it gives you is certainty, and a second written price for the repair or the replacement.
Is a cracked heat exchanger always a replacement?
Not always, but usually on an older furnace. The part can be replaced for $1,500–$3,000, and where the manufacturer's warranty still covers the heat exchanger you pay labour only. Past 15 years the blower, inducer and control board are the same age, so the money generally goes further in a new furnace. See how to tell if a heat exchanger is cracked.
Can I keep running the furnace while I wait for the second visit?
If a technician shut it off and tagged it, no: leave it off and use electric space heaters until it is re-tested. If no tag was issued, the furnace was not formally declared unsafe, but book the visit promptly and confirm a working carbon monoxide alarm sits outside the bedrooms. If any CO alarm sounds, leave the house and call from outside.
I signed a contract at the door yesterday. What now?
You have options. Contracts signed in your home carry a 10-day cooling-off period, and a furnace contract that came from an uninvited sales visit is void under Ontario's 2018 rules. Send the cancellation in writing, keep a copy, and have the furnace tested independently before agreeing to anything else. Consumer Protection Ontario takes complaints about sellers who ignore a cancellation.
Do you give second opinions on water heaters and air conditioners?
Yes. The approach is identical: test, photograph, record the readings and put the recommendation in writing. Tagged water heaters and venting defects are covered on our red tag repair and clearance page, and a general check before a home purchase is an HVAC inspection.