A plumber in Georgia ran into an alarming HVAC issue while helping at his grandmother's older house. It had duct insulation that was "soaking wet" and dripping near a furnace that appears to be decades old.

Here's what to know

In a Reddit thread on r/hvacadvice, the plumber explained that he had been working at his widowed grandmother's home in Marietta, Georgia — a house built in the 1940s or 1950s — when he discovered moisture saturating the duct insulation.

In the plumber's words, "ALL of the insulation on her duct work was soaking wet," and it was "steadily dripping off the duct work right off the back of the furnace."

The responses did not point to just one possible cause, but many commenters focused first on drainage and airflow.

"Could be as simple as a plugged condensate drain, could be lots more. But start there," one commenter wrote.

Another reply suggested the system may date to 1985, highlighting just how old the equipment could be. That fit with other concerns raised in the thread, including one commenter's assessment that "the equipment is definitely well beyond its expected service life."

Another commenter warned: "Tell your grandma to call a HVAC contractor and have a carbon monoxide test done first off. That is a very, very old Furnace and probably has a cracked heat exchanger and by the looks of that A coil it is probably filled with dust and dirt and restricting your airflow which in return will make the ductwork sweat. Also check your furnace filter and see if the outside condenser needs hosed off. I suppose it's possible on R-22 also."

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What can be done?

In this case, a technician should inspect the condensate drain, A-coil, furnace filter, and outdoor condenser, since those were among the first problem areas commenters flagged. Because the furnace may be especially old, a carbon monoxide test is also a sensible way to check for a more serious hazard.

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Where can I learn more?

Other home-heating stories show how wet ductwork, aging equipment, and combustion risks can collide.

• One homeowner smelled gas near a new furnace and learns that 180 parts per million is too high for indoor safety.

• After a contractor's improper installation, carbon monoxide filled his home and shattered the owner's confidence.

• In a basement, a hidden duct gap led pros to warn that the material was "1,000% asbestos."

• After basic air conditioning maintenance, one homeowner faced a suspicious $20,000 quote that raised red flags.

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