Gas furnace leak and rust !
High efficiency gas furnace leak and rust after 3 years of operation .
Who is responsible ? Manufacturer, Contractor installer, Owner.
The High efficiency furnace is producing condensate water which is drained by one of the side of collector box of the furnace, depending in which position is installed the furnace.
Manufacturer is not seal properly the side of the collector box. Contractor install the furnace and depending of the installer technician they can miss this detail.
The owner use the furnace without any inspection during this time.
The consequence are rust inside the furnace. For long time the consequence are worst, as you can see in the right side of the image.
The professional should look at all details !