what is the correct vent size for a 50000 BTUhr input induce

what is the correct vent size for a 50,000 BTU/hr input induced-draft furnace with a 15-ft lateral run and a 30-ft vent height?

Solution

from the table 30 feet height and 15feet lateral run under the FAN min and FAN max column giving the 37000 and 150000 BTUH for a 4 inch vent.generally the smallest diameter that will do the job is preferred