Refer to Table 13-3 in the 1997 UMC. Use the installation information.
Gas type: natural pressure
Gas pressure: 80
Specific Gravity: 0.60
Pressure drop: 0.5″ water column
Heating value:1,000 btu/h per cubic foot
Appliance: warm airfurnace
Rating:120,000 btu/ h
System=natural convection appliance
Location=50 feet from gas meter.
What minimum diameter gas line is required for the supply to the furnace?