what is btu rating
The British thermal unit (BTU or Btu) is a traditional unit of work equal to about 1055 joules. It is the amount of work needed to raise the temperature of one pound of water by one degree Fahrenheit (Physical analogue: one four-inch wooden kitchen match consumed completely generates approximately 1 BTU).efinitions of the BTU based on different water temperatures can therefore vary by up to 0.5%. A BTU can be approximated as the heat produced by burning a single wooden kitchen match or as the amount of energy it takes to lift a one-pound weight 778 feet (237 m).