In order to calculate heat flow, one must know the amount of time and what else?

To calculate heat flow, it is essential to know not only the duration of time but also the amount of heat being transferred, which is measured in British Thermal Units (BTUs). BTUs quantify the energy required to raise the temperature of one pound of water by one degree Fahrenheit. Knowing the heat in BTUs allows you to understand how much energy is moving over a specific period, making it fundamental to calculating heat flow accurately.

Temperature is important in the overall heat transfer process, as it helps determine the direction of heat flow and how much heat can potentially be transferred, but it does not quantify the actual amount of heat flow itself. Pressure and volume also play roles in refrigeration cycles and system performance, but they are not directly linked to calculating heat flow in the same way that BTUs are. Thus, having BTU values is crucial for understanding and calculating heat flow in HVAC systems.