NATE Air Conditioning and Heat Pumps Practice Exam 2025 – All-in-One Guide to Master Your Certification!

An oversized heat pump significantly affects energy efficiency by causing the system to cycle on and off frequently. This phenomenon, known as short cycling, occurs because the system is too powerful for the space it is intended to heat or cool. When the heat pump is oversized, it reaches the desired temperature too quickly, which triggers the thermostat to shut it off. Shortly after, the temperature can drop again, prompting the system to turn back on.

This rapid cycling leads to several issues related to efficiency. First, it prevents the heat pump from operating for extended periods, which is when it generally runs most efficiently. Additionally, frequent on-and-off cycles can cause greater wear and tear on the components of the system, potentially leading to increased repair costs and a shortened lifespan for the equipment. In summary, while it might seem beneficial for a heat pump to have a higher capacity, being oversized ultimately undermines energy efficiency due to the negative impact of frequent cycling.