When you need to calculate the Energy Factor for miscellaneous types of hot water heaters.

Use the following link to open this calculator as an active Excel file.

Energy Factor Calculator for DHW tanks

Screenshot of calculator -

References:

Energy Star HIGH EFFICIENCY WATER HEATERS - with details

Includes Power Vent Models, Tankless, Nybrid Electric, Hob Water Boiler

TANKLESS COIL AND INDIRECT WATER HEATERS - Energy.gov