They are annealing furnaces from the early 80's and manufacturer gone out of business.
I think I've figured it out. First I was multiplying by 60 not dividing to get btu's per minute... I also found a formula in the Combustion Handbook for flue gas flow in cfs = [BTU/hr input * ( flue gas...
I've been given a project to replace 2 existing exhaust fans. There are 4 total in two systems which are similar but operate separately. Each system has a duty fan and a stand-by. A few years ago the other two fans were replaced with smaller capacity fans. The original fans were 48,000 cfm...
