Ask what the estimate already knows
Request the heating and cooling load assessment, exact proposed models, equipment match, and the information used about insulation, windows, air leakage, and room layout. Ask which facts were verified, which came from your answers, and which are assumptions.
A site visit without a documented assessment can also leave gaps. The useful question is, “What evidence supports this size and this installation plan?”
If two quotes differ, ask both contractors to explain their inputs. Do not assume the lower price is wrong or the visiting contractor's size is right simply because the methods differ.
Identify what needs direct confirmation
Ask who will verify the existing equipment and airflow, electrical needs, outdoor support and clearances, refrigerant route, drainage, access, and room coverage. Have the contractor identify any condition that cannot be settled remotely.
We would want direct assessment before a final commitment where an unresolved site question could change feasibility, safety, or material cost. Ask whether the quoted price is an estimate or a firm scope and what changes could increase it.
If separate electrical, duct, or home-performance work is needed, request a named responsible provider and coordination plan. A list of photos to upload should not hide a major unassigned part of the project.
Check what happens before and after installation
Request the final design review point, the process for equipment substitutions, and who approves a price change. Ask what commissioning checks (startup tests that verify installed operation) and homeowner instructions will be provided after installation. Professional commissioning guidance.
Keep the estimate, assumptions, photos, and final scope together. If new information changes the design, ask for the updated explanation before the equipment is ordered.
Your next step is a short list of unresolved facts and the owner who will verify each one. A remote estimate can be useful, but we would accept the final proposal only when the home-specific evidence and full installation responsibilities are clear.