What is the formula for calculating the power of a heat pump?

The formula for calculating the power of a heat pump is based on the relationship between the heat output, often measured in BTUs (British Thermal Units), and the efficiency of the heat pump system. Efficiency in this context typically refers to the Coefficient of Performance (COP), which denotes how effectively a heat pump converts electrical energy into heat.

Using the formula Power = BTUs / Efficiency is correct because it illustrates that the power (in watts or another relevant unit) required by the heat pump is determined by dividing the total heating output by how efficiently the machine operates. This means that the more efficient the heat pump is, the less electrical power it will require to generate a certain amount of heating output.

In contrast, the other options do not accurately reflect how these variables interact. For instance, multiplying BTUs by efficiency would erroneously suggest that power increases with higher efficiency, which contradicts how these systems typically operate. Similarly, expressing power as a ratio of efficiency to BTUs or as a sum does not represent the physical principle behind how heating power is calculated. Therefore, the ratio of output to efficiency is the correct approach to determine the power requirement for a heat pump.