Bradford White's eF Series™ line has now grown to seven models with the addition of one 100-gallon and three 60-gallon units. This series is now available in 60-gallon capacities with 125,000, 150,000 and 199,999 Btus, and in 100-gallon capacities with 150,000, 199,999, 250,000 and 300,000 Btus. All eF Series™ models feature remarkable thermal efficiency ratings as high as 99.1% and offer the ability to vent unbalanced the equivalent of up to 120 feet utilizing 3" ABS, PVC or CPVC piping, or 170 feet utilizing 4" ABS, PVC or CPVC piping. Bradford White Corp.