What equation represents the first law of thermodynamics in HVAC systems?

The first law of thermodynamics, often referred to as the law of energy conservation, states that energy cannot be created or destroyed; it can only be transformed from one form to another. In the context of HVAC systems, this principle is critical for understanding how energy is transferred and utilized within the system.

The equation that best represents this principle is that energy input into the system equals the energy output plus any energy that is stored within the system. This means that when energy is introduced into an HVAC system, some of that energy is used to perform work, while some may be stored temporarily in the system (for example, in the thermal mass of the building or in refrigerant).

This relationship emphasizes that all energy entering the system must either leave the system or be accounted for as stored energy, thus ensuring that energy conservation is maintained. This understanding allows HVAC professionals to properly design, analyze, and optimize systems for efficiency.

Other options present variations that do not accurately capture the conservation of energy principle as clearly as the correct choice.