An exhaust fan needs a matching intake path; increasing the fan size does not create one. Ask the installer to assess intake provision, ceiling leakage and compatibility with passive vents.
Describe the problem before sizing equipment
Tell the contractor what prompted the fan proposal: a particular moisture observation, a hot room or an existing unit that stopped operating. Record where and when the condition appears. Those are different starting points and may require different investigations. Ask the installer what observations support replacing the fan and what other parts of the attic arrangement were examined before a larger unit was suggested.
Request a system-level proposal
The proposal should identify the fan model, intended intake arrangement and existing openings that will remain. Ask whether ceiling leakage or attic access sealing needs a separate assessment. Identify electrical responsibilities and controls so the roofing contract does not leave an unfinished connection. If the installer recommends changing another component, request the reason in writing rather than treating it as an unexplained extra after the fan is already installed.
Choose evidence for the follow-up
Agree on how the original complaint will be reassessed. For a moisture concern, preserve the locations and dates of observations so later photographs can be compared. For an equipment failure, retain the service findings and final operating instructions. Avoid evaluating the entire roof solely by whether the new fan runs audibly. Save the selected model and supporting design information with the roof records, including any conditions the installer could not evaluate.
If the existing fan has stopped, keep any service diagnosis that explains the failure. That information is different from evidence about whether the original ventilation arrangement was suitable. Ask the installer to separate equipment repair findings from a recommendation to redesign the system. A replacement can then be priced clearly, with additional investigation identified instead of folded into an unsupported performance claim.
For related project preparation, see roof ventilation changes during replacement and roof replacement sequencing with attic insulation work. Bring the relevant photographs and existing proposal to Perkins when discussing the roof-specific scope.
Technical references: GAF: powered vents and intake; PNNL: attic access air sealing. These references provide background; the selected assembly and applicable project requirements determine the installation detail.