Useful Conversions and Formulas

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  • Heating oil energy content: 138,690 BTU / gallon
    Typical Oil burner effieciency: 78% - 95%
    Electricity energy content: 3413 BTU / kwh
    BTU definition: Amount of energy needed to raise 1 lb water by 1*F at 58*F

    Water volume conversion: 1 ft3 = 7.4805 gallons
    Water density: 62 lb / ft3 = 8.3 lb / gallon


    Ex calc:
    I use 175 gallons of oil / month in the winter. Using 85% burn efficiency I need about a million BTUs per day in the winter.

    Between 140*F and 180*F my 800 gallon Heat Storage will store: (800 gal) * (8.3 lb / gal) * 40F = 266kBTU.