Need info how to put the duct work on a FREDRICH FURNACE serial number 612141
I'm confused. Are you sure about model number of FrIedrich furnace? Where is furnace located in house? By cool air at bottom do you mean inlet? Is there return ducting to it? Or is open return? Hot air outlet is on top? Measure inlet and outlet openings. Should be raised lip around outlet, measure outside dimensions. Inlet ducts often go inside opening, measure inside dimensions, you can go outside lip and seal connection real good. Get ducting of same size or union to join to existing ducting and/or plenum. Some plenums are of size to just be connected to outer sides of top of furnace. Seal all joints with metal DUCT, not ducK, tape.
Measure twice, cut once.
Look at the nail, not the hammer. Watch the fence, not the blade.
If you hook your thumb over your belt you won't hit it with the hammer or leave it layin on the saw table.