Useful Conversions and Formulas

  • Views Views: 3,156
  • Last updated Last updated:
  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
  • 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.