A heat exchanger is the metal barrier between the combustion gases inside your furnace y the air that heats your hogar. When it cracks — y en older furnaces, it's almost always when, not if — the combustion gases mix con your indoor air. That includes carbon monoxide, which kills about 400 Americans a year y sends 50,000 more to emergency rooms.
The crack is usually invisible to the naked eye, y the soot patterns that give it away are hidden inside the burner box. We find it con combustion analyzer readings: measuring O₂, CO, y stack temperature at the flue, y comparing them against manufacturer specs. A healthy 95%-efficient furnace reads 2-5 ppm CO en the flue; a cracked heat exchanger pushes that into the hundreds, y those gases are leaking into your hogar's air handler.
Heat exchangers crack de thermal cycling stress — expansion y contraction every time the furnace fires. Fifteen to twenty años de cycling is the typical failure point. If your furnace is en that age range, a combustion analysis is the only way to know para sure. We include it en every fall tune-up, y the replacement-vs-reparación math tilts decisively toward replacement once a crack is confirmed.
A healthy 95%-efficient furnace reads 2-5 ppm CO. A cracked exchanger pushes that into the hundreds.
If your furnace is under 10 años old y still shows garantía coverage, a cracked exchanger is often a free part swap (we handle the paperwork). Over 10 años, the manufacturer garantía is usually expired y the reparación cost can exceed 50% de a new furnace — at which point replacement is the right call. Either way, running a furnace con a confirmed CO leak is not an option, y we will not re-light a unit that fails combustion analysis.
