Responded to no-heat complaint on 10+ year old York LP modulating furnace. Detected aldehyde odor indicative of rotted secondary heat exchanger upon arrival. Inspection confirmed secondary heat exchanger failure with visible perforation, excessive black exhaust deposits, and water accumulation around unit. Visual inspection via camera showed customer the deteriorated component. Determined likely cause was previous gas valve malfunction leading to sooting, secondary heat exchanger plugging, and subsequent corrosion. Equipment was shut down and tagged out for safety due to carbon monoxide hazard. Customer declined repairs based on system's ongoing reliability issues.
