BTU per hour to Horsepower (mechanical) Converter

One BTU per hour is exactly 0.29307107017222 watts, because one BTU is exactly 1,055.05585262 joules and an hour holds 3,600 seconds. The symbol is BTU/h.

Air conditioners, heat pumps, furnaces and chillers are rated in BTU per hour, and the figure on a room air conditioner describes its cooling capacity. Heating and cooling engineering uses the same unit for equipment sizing.

BTU per hour measures a rate, so it must be multiplied by a duration to produce an energy amount. Converting it to watts uses the exact factor, and 12,000 BTU per hour works out to about 3.5 kilowatts.

Treating BTU per hour as a unit of energy is a common error, since the same letters without the time element name an amount. A capacity rating and a consumption figure are therefore different quantities.

Cooling and heating capacities are quoted in BTU per hour, the electrical draw of the same equipment is quoted in kilowatts, and its motor may be quoted in horsepower. Choosing the wrong sibling changes the number by a factor of more than three.

Mechanical horsepower is exactly 745.7 watts, and metric horsepower is exactly 735.49875 watts. The two definitions differ by about 1.4 percent, so a figure carries a larger number in mechanical horsepower.

Vehicle engine output, pump and compressor motors, and agricultural machinery are commonly rated in horsepower. Metric horsepower is used for engine figures in much of Europe and Asia, while mechanical horsepower dominates in the United States.

Power is a rate, so multiplying horsepower by a running time gives an energy amount in joules or watt-hours. The gap of about 1.4 percent between the two horsepower definitions is carried through every conversion to watts.

Comparing two engine ratings without knowing which horsepower definition applies is the usual error, and the numbers are not interchangeable. The definition behind a figure should always be established before it is converted.

Horsepower is the unit for engine output, while kilowatts fit appliances, generators and inverters, and BTU per hour fits heating and cooling equipment. Metric horsepower is a separate sibling, so a PS figure and an hp figure differ even when they describe the same engine.