ENERGY STAR Certified Bradford White High Efficiency Condensing eF Series® 100 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 -859 indicates that this SKU comes with a Gas Regulator. The -897 indicates that this SKU comes with magnesium anodes.