Cubic metres M3 take a reading of meter. Time it for 2 minutes, take another reading. Take thisreading from the first reading and multiply by 321. This will give you a reading in kilowatts.
Cubic feet ft3...... time 1 revolution of the dial in seconds. 1090 divided by the result will give you the result in kilowatts. Compare this to the OUTPUT of the boiler.
jeff stockdale, February 2011