Document the condition
Note where the issue shows up, when it started, whether storms or heat seem to trigger it, and what's already been tried—a couple of photos help the first call.
Read the local context
Two observations make the first visit far more productive. Note which rooms are uncomfortable and in which season, because upstairs-warm-in-summer in a large two-story house usually points at zoning and duct design rather than at capacity -- and adding capacity there tends to make it worse. Then find out where the equipment and ductwork actually live, since in these houses that is commonly unconditioned attic space where leakage costs far more than the same leakage would elsewhere. Have the system's age to hand as well.
Ask what will be hidden
A scope focused only on equipment misses the point—duct leakage, insulation, and electrical capacity matter just as much, and it should explain how that hidden work gets verified once it's closed up.
Compare complete scopes
Hold every quote to the same list: protection, access, materials, permits, testing, and what counts as a change order.
What official local sources add
The useful point in the city's permit guide is that it separates review by trade rather than by project size, which is why an equipment swap that feels like maintenance is treated as permitted work. Replacing a furnace, an air handler or a condensing unit generally carries a mechanical permit and an inspection, and where the work touches electrical supply or gas piping those are separate reviews again. That has a practical consequence worth knowing: an unpermitted replacement can surface later at resale or on a warranty claim, so confirming that the permit was pulled is a reasonable question to ask before work starts rather than after.
Sources were reviewed June 20, 2026. Confirm parcel-specific flood zones, historic-district status, permits, and current requirements with the relevant authority before authorizing work.