Document the condition
Jot down where the problem shows up, when it started, whether weather seems to trigger it, and anything already tried—photos and a rough measurement or two go a long way on the first call.
Read the local context
The University of Illinois, chartered in 1867 as a land-grant institution and opened the following year, is the reason so much of this housing stock is rental, and that has a direct bearing on mechanical systems: equipment in a rental is commonly replaced at failure rather than at end of life, so a house can hold a system well past the age at which it stopped being efficient. The climate is what tests it. East-central Illinois runs a genuinely wide annual range, from humid summers to hard winters, so a system here has to do both jobs well -- and in summer the real work is removing humidity, which an oversized unit does badly because it satisfies the thermostat and shuts off before it has dehumidified. Duct layout in older houses converted over the decades is the other recurring problem.
Ask what will be hidden
A written scope should explain the preparation and verification that will no longer be visible at completion, not just the finished appearance.
Compare complete scopes
Line up every quote against the same list: protection and access, materials, permits, testing, cleanup, and what triggers a change order.
What official local sources add
Very little of the city's stormwater framework reaches heating and cooling work, and it is worth being straight about that rather than implying otherwise. The one genuine intersection is condensate — a cooling system produces water, and where that discharge is routed into the municipal stormwater drainage system as a new or modified connection, the city's permit applies. Setting outdoor equipment on a new pad can also count as ground disturbance. Otherwise your permits here are mechanical and electrical rather than site-related.
Sources were reviewed 2026-07-26. Confirm parcel-specific flood zones, historic-district status, permits, and current requirements with the relevant authority before authorizing work.