Which of the following is a component of a Heat Recovery Ventilator (HRV)?

A Heat Recovery Ventilator (HRV) is designed to bring fresh outdoor air into a building while simultaneously exhausting stale indoor air, all the while recovering energy from the outgoing air to pre-condition the incoming air. The primary component that allows for this function is the cabinet, which houses the heat exchange core where the transfer of heat occurs. This cabinet includes the necessary fans, filters, and ducts for the incoming and outgoing air streams, making it essential for the operation of the HRV system.

Other options, such as a refrigerant line, thermostatic expansion valve, and condensing unit, are typically components associated with refrigeration systems or air conditioning units. They do not play a role in the operation of an HRV, which focuses on air exchange and energy recovery, highlighting that the cabinet is indeed the correct answer as a fundamental part of an HRV system.