November 28th, 2017
After our RV Tech, Scott Paine, came to review the furnace in November, we found out that Suburban had authorized a replacement unit. Scott came back out to install the new innards into the housing. It did not take him very long, and thank goodness, as the temps were dropping that day to below freezing that night.
He left, and the furnace was producing the "new" smell, typical of a first time use. After running a while, the "new" smell burned off, but the old offensive smell remained, especially after the unit ran a while.
So, we felt there had to be another cause.
December 8th - 9th, 2017We decided to do some more testing with the ductwork, thinking maybe that was the culprit. Since the area behind the basement wall is fairly easy to work in, we removed the 3 ducts that were in this area. It is called Hi-Tech Duravent M-KC Thermaflex Series Fiberglass Thermaflex Air/HVAC Duct Hose. Unfortunately, we had only one weekend to work on this project, so we opted to try another product, available at the local Home Depot. We picked up the Master Flow Insulated Flexible Duct R6 Silver Jacket, used in standard Heating and Air Conditioning (HVAC) systems. We replaced the ducts and tried again to run the furnace for a while.
Success! The ductwork change made quite a difference. We can still smell the smell, but not so much that it is difficult to breathe or that it gets worse. We ran the furnace over the next week, and it was a great improvement. I think we have solved the issue!
So what caused it? We aren't sure. But we*think* the furnace somehow overheated at some point, some way, causing the burned metallic smell to permeate the silver fiberglass ducts. Or, it could be related to the airflow -- the new vents are more insulated, and thus more efficient. They are pushing out more air into the bedroom, bath and hallway, possibly causing the furnace to perform more efficiently than the old ductwork. Either way, we are happy with the results.
New silver insulated ductwork installed.