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A contractor quoting a furnace installation here has to work out what the house actually demands before they can size the equipment, and the county's weather history is only part of that picture. 93 severe weather events were recorded in Montgomery County, Illinois between 2015 and 2024. That rate puts severe weather somewhere in the middle range of what heating equipment around the country runs against, which means climate load alone does not decide what size unit a house needs or how hard the installation has to work. Duct layout, building envelope, and how well the previous system was matched to the load are what a contractor pins down first.
Ductwork laid down for the furnaces of an earlier era was built to move air in ways that do not map onto what a new unit demands. Half the homes in Montgomery County, Illinois were built in 1964 or earlier (2020-2024 ACS 5-year). That gap between the building's original design and what a contractor is now fitting into it is where the real work of an installation sits. The electrical side follows the same logic: service panels from that period were not wired with today's equipment loads in mind, and a contractor scoping a furnace replacement has to open that question before the equipment question can settle.
What Gets Installed With a New Furnace
The furnace itself sits in the basement, utility room, or mechanical closet and is the heart of what a contractor installs. Inside it, the heat exchanger and burner assembly do the work of producing heat, while the blower motor pulls air across them and pushes it into the supply side of the house.
The flue pipe runs from the furnace to an exterior wall or up through the roof, carrying combustion gases out of the living space. Alongside it, the contractor installs the gas valve, the igniter, and the control board that ties those components together and tells the system when and how to run.
The drawing shows a typical layout, and a licensed contractor determines exactly what applies to this house.
Get matched in Montgomery CountyMontgomery County, by the numbers
93 severe weather events were recorded in Montgomery County, Illinois between 2015 and 2024.
NOAA National Centers for Environmental Information, Storm Events Database, bulk CSV export, events 2015-01-01 through 2024-12-31.Half the homes in Montgomery County, Illinois were built in 1964 or earlier (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesMontgomery County, Illinois holds 12,495 housing units (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesOwners occupy 77.4% of the occupied homes in Montgomery County, Illinois (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesFurnace Installation Rules & Standards for Montgomery County, Illinois5 sourced regulations and standards
What the Job Looks Like in Montgomery County
Non-weatherized gas furnaces manufactured on or after November 19, 2015 must reach 80.0 percent AFUE.
Non-weatherized oil-fired furnaces manufactured on or after November 19, 2015 must reach 83.0 percent AFUE.
Mobile home gas furnaces manufactured on or after November 19, 2015 must reach 80.0 percent AFUE.
Non-weatherized gas furnaces manufactured on or after December 18, 2028 must reach 95.0 percent AFUE, up from the 80.0 percent minimum that applies to units manufactured before that date.
What Montgomery County, Illinois Requires for This Work
Illinois leaves HVAC licensing to the municipality: state law lets the corporate authorities of each city or village examine, license and regulate heating, air conditioning and refrigeration contractors, and caps the licence fee they may charge at $50 — so who licenses you depends on the town you work in.
Severe Weather Events in Montgomery County
Weather conditions place real demand on heating equipment, and that demand varies by location. How hard a furnace has to work over its lifetime is a local question, and the pattern of weather events recorded here is part of what shapes the answer.
93 severe weather events, 2015–2024. Source: NOAA National Centers for Environmental Information, Storm Events Database.