Compatibility is non-negotiable
Do not mix indoor units, outdoor units, controls, or service procedures across refrigerants unless the manufacturer explicitly lists the combination. EPA notes that A2L refrigerants may not be used in systems that were not designed for them.
What the contractor confirms
The installer should confirm the listed system match, charge and line requirements, tools and recovery equipment, leak-detection or mitigation requirements, transport/storage practices, labeling, and local code adoption.
Primary sources
Use these agencies as the source of truth. Summit summarizes them for equipment planning and does not provide legal, tax, engineering, or permit advice.