How do you know if a furnace heat exchanger is actually cracked?
Determining if a heat exchanger is truly cracked often requires using a borescope to inspect it from multiple angles, as technician photos can be ambiguous. When a technician flags an older, unmaintained furnace for safety failures, homeowners are left questioning whether it is a genuine hazard or an attempt to make money.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1Using a borescope to inspect the outside and inside from multiple angles.
- 2seeking second opinions
- 3inspecting the heat exchanger for manufacturing marks or dust lines
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“Here's a pic from my HVAC guy. Is this or is this not a cracked heat exchanger?”source ↗
“Its hard to say, id lean toward yes, but id be looking at it from another angle to verify ie put your borroscope in under the A coil and check the outside of it, if it can be seen from both sides, its fucked. It doesbt look good though”source ↗
“Recently got maintenance on my furnace in my new home. 14 year old furnace that hasn't had any maintenance done previously. The technician stated the furnace failed safety inspection and should not run until fixed. There are multiple cracks in the heat exchanger. Is this as big a issue as the technician said it is? Or do they just want my money.”source ↗