Bradford White High Efficiency Condensing Ultra Low NOx eF Series® 60 Gallon Commercial Gas (Natural) Water Heater. Designed for Venting Versatility, this water heater can be installed as a Power Vent or Power Direct Vent. 3-Year Tank Warranty, 199,999 BTU/Hr., 120 Volts, Single Phase, with Power Cord included. The -879 indicates that this SKU operates on a Gas Supply Pressure Range of 3.5 - 14 W.C.