How many ccf natural gas to heat cup of water?

Answer 1

That's going to depend on

-- starting temperature of the water

-- finishing temperature of the water

-- efficiency of the method you use to heat the water.

But we'll play the game.

Here are the numbers we're using:

Energy content of typical commercial grade natural gas in the US: 1,000 BTU per ft3

or 100,000 BTU per ccf.

Heat capacity of water: 1 BTU per pound-mass per degree Fahrenheit.

Density of water: 8.34 lb/gallon = 0.52125 lb-mass per cup

From this MASH-up, we get

(1 cup) x (0.52125 lbm/cup) x (1 BTU/lbm-degree) / (100,000 BTU/ccf) = 0.0000052125 ccf per degree Fahrenheit

Example: To raise the temperature of 1 cup of water 100 degrees:

0.0000052125 x 100 = 0.052125 cubic foot of natural gas, IF all of the energy

in the natural gas could be transferred to the water.

Answer 2

It would depend on the efficiency of the natural gas heating system, the temperature of the water, and the starting temperature of the water. In general, it would likely require a fraction of a cubic foot of natural gas to heat a cup of water.