NATE Air Conditioning and Heat Pumps Practice Exam

The correct choice indicates that the maximum sensible cooling capacity of a heat pump should be within +25% of the calculated sensible heat gain for a building that has a substantial heating load. This percentage accounts for the fact that many heat pumps are primarily designed for heating and may have slightly less efficiency in cooling mode, especially under certain load conditions.

When assessing cooling capacity, it's crucial to ensure that the system can adequately handle peak loads without exceeding the sensible heat gain calculations. If the heat pump’s capacity is too far below the sensible heat gain, it could lead to inadequate cooling during hot weather. Allowing for a +25% margin provides flexibility, recognizing that extreme conditions may necessitate slightly higher capacities to maintain comfort levels within the space being cooled, especially if the building was primarily designed with a heating focus in mind.

In contrast, narrower limits may not provide enough leeway for variance in heat loads or unexpected high temperature days, potentially compromising comfort and system performance. This ensures that system sizing accounts for realistic operational conditions and maintains efficiency throughout its use.