Defect
THE FURNACES WERE IMPROPERLY INSTALLED. A 1 1/4" MINIMUM OVERLAP BETWEEN THE CHAMBER EXHAUST TUBE AND THE VENT ASSEMBLY EXHAUST IS NEEDED FOR PROPER EXHAUST.
Consequence
THIS CONDITION CAN LEAD TO CARBON MONOXIDE POISONING.
Remedy
DEALERS WILL REPLACE THE FURNACE VENT ASSEMBLY.