Tell us about the job
Takes about a minute. No obligation.
Sizing a furnace for a Jefferson County home is not a catalog exercise. 234 severe weather events were recorded in Jefferson County, Alabama between 2015 and 2024. At that rate, severe weather is a standing condition of operating here, and it bears directly on how a contractor calculates heating load, selects equipment, and sets up the install. A unit that is undersized or poorly sealed against the demands of this climate will cycle harder and recover slower every time conditions push it. A licensed contractor factors that in before the equipment is ever ordered.
Older ductwork sized and routed for a different generation of equipment is what a furnace installation in Jefferson County actually runs into first. Half the homes in Jefferson County, Alabama were built in 1975 or earlier (2020-2024 ACS 5-year). That gap between when a house was built and what a contractor is now putting in it is where the job gets decided. Trunks that made sense for an earlier system may restrict airflow or need reconfiguration before a new furnace can perform as rated. The electrical is a separate check. Both have to be confirmed before the equipment selection means much.
What Gets Installed With a New Furnace
The furnace itself sits inside the house, most often in a basement, utility closet, or dedicated mechanical room. It is the box that produces the heat. A flue or vent pipe runs from it to an outside wall or through the roof, carrying combustion gases out of the living space.
The air handler or blower compartment, which may be part of the furnace cabinet or a separate unit, moves conditioned air into the supply side of the home. A thermostat goes on an interior wall and gives the homeowner control over when the furnace fires and what temperature it holds.
The drawing shows a typical layout, and a licensed contractor determines what applies to your house specifically.
Get matched in Jefferson CountyJefferson County, by the numbers
234 severe weather events were recorded in Jefferson County, Alabama 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 Jefferson County, Alabama were built in 1975 or earlier (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesJefferson County, Alabama holds 310,789 housing units (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesOwners occupy 63.9% of the occupied homes in Jefferson County, Alabama (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesFurnace Installation Rules for Jefferson County, Alabama5 codes, standards, and statutes
What the installation looks like from your side
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.
Licensing and Legal Requirements in Jefferson County, Alabama
Alabama requires state certification to do heating, air conditioning and refrigeration contracting: nobody may advertise, bid, pull permits or do the work unless the person in responsible charge is a certified contractor.
Severe Weather Events in Jefferson County
Weather in Jefferson County puts real cumulative stress on heating equipment, from cold snaps that run furnaces hard to storms that knock out power and force systems to cycle back up under load. How often that happens here shapes what a furnace needs to handle and how a contractor sizes and installs it.
234 severe weather events, 2015–2024. Source: NOAA National Centers for Environmental Information, Storm Events Database.