diagnosed three 9 year old Lennox furnaces in the same house with cracked heat exchangers. I was called for a second opinion.
I'm always cautious when rendering an opinion on cracked heat exchangers giving the previous tech every benefit of a doubt, after all he may have seen something I didn't. He claimed carbon monoxide levels exceeding 147 ppm on one furnace, 30 and 14 on the others with all reading taken within the living space. Further claimed that temperature reading taken at the curve in the heat chamber registered 68 when it should have been 58. What???
Anyway I tested it with a Testo 825-M and during an hour at the home found the only elevatged reading (+1 ppm) inside the residence was at the kitchen range which was off. There was, however, an aquarium there and a coffee pot was plugged in so I think the moisture from those gave me a false positive.
I then tested the units and found no failures.
Previous tech suggested that the heat exchangers needed to be changed and the cost would be $700 each.
My question: does it sould like a scam or was the tech just poorly trained? Or better yet - was he a well trained scam artist?