2 in intake/vent nominal pipe, 19-1/2 in L air inlet pipe|Note: the concentric vent reduces the allowable intake/vent piping length by 5 ft from that listed in the basic furnace installation instructions|The combustion air and vent pipe fittings must conform ANSI and ASTM standards D1785, F891, D2665, D2241, D2661 or F628, pipe cement and primer must conform to ASTM standards D2564 or D2235|In Canada, construct all combustion air and vent pipes for this units of CSA or ULC certified SCH 40 PVC, PVC-DWV or ABS-DWV pipe and pipe cement

ANSI/ASTM D1785/F891/D2665/D2241/D2661/F628/D2564/D2235