According to Section 407.4.1.7, a recirculating room HVAC unit may provide the portion of the minimum total air changes per hour that exceeds the outdoor air requirement. Which of the following is NOT a requirement for such a unit?

• It must serve only a single space.
• It must provide filtration for airflow passing over any designed cold surface.
• It must not receive nonfiltered, nonconditioned outdoor air.
• It must be connected to a central exhaust system for the space.