1. A method of creating a visual depiction of variations in predicted fuel usage for heating a structure comprising the steps of: calculating an historic winter burn rate required to maintain said structure at a constant temperature and providing a graphic depiction thereof; determine a number of heating degree days since a last fuel delivery; determine an amount of fuel in the last fuel delivery; divide the amount of fuel by the heating degree-days to obtain an actual burn rate; adjust the actual burn rate for fuel used in domestic hot water production; adjust the actual burn rate for pilot flame fuel use; providing a graphic depiction of the adjusted actual burn rate; and comparing the graphic depictions of the adjusted actual burn rate to the historic winter burn rate in order to determine if a discrepancy exists that indicates a failure in the heating of the structure.