"John F." wrote in message
...
To help answer my own questions and for those who may be intereted a
gallon of propane delivers 92,000 BTU's vs fuel oil which delivers 130,000
BTU per gallon or 41% more heat. No luck yet on finding out the number
BTUs delivered by natural gas.

Wikipedia mentions that the calorific value of natural gas is between 35,000
and 40,000 kilojoules per cubic metre, depending on the source (38,000 for
the USA). That heat would be at available only 100% efficiency!

Another site mentions a US value of 1.03 million BTUs per 1000 cu. feet.