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A furnace installation in Lewis County has to be sized and fitted correctly from the start, because the burner and heat exchanger do not get much time off. Homes in Lewis County, MO run heat about seven months a year, from October through April. The ignition system cycles through that span repeatedly, and an undersized unit or a poorly sealed duct run shows the strain before a well-installed one would. A contractor quoting a replacement here works out the load calculation for this house before settling on equipment, not after.
Ductwork laid in for older equipment carries specific dimensions and load assumptions, and a new furnace has to work within whatever that original installation allows. Half the homes in Lewis County, Missouri were built in 1969 or earlier (2020-2024 ACS 5-year). That history shows up in the plenum sizes, the branch runs, and the static pressure a contractor measures before the new unit goes in. Where the existing duct network cannot move the volume the new furnace demands, the ductwork gets addressed first, and the furnace follows.
What Gets Installed With a New Furnace
The furnace itself sits in a utility room, basement, or closet and is the piece that generates heat for the house. A burner assembly inside it fires on demand, and a heat exchanger transfers that heat to air moving through the cabinet. The blower motor then pushes that warmed air out into the supply side of the home.
The flue pipe runs from the top or back of the furnace to an exterior wall or up through the roof, carrying combustion exhaust out of the house. Alongside the furnace, the contractor installs a new thermostat on an interior wall to give the system a control point, and a filter housing at the air return to keep particulates out of the cabinet.
The drawing shows a typical layout, and a licensed contractor determines exactly what applies to this house and its existing setup.
Get matched in Lewis CountyLewis County, Missouri, by the numbers
65 severe weather events were recorded in Lewis County, Missouri 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 Lewis County, Missouri were built in 1969 or earlier (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesLewis County, Missouri holds 4,320 housing units (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesOwners occupy 76.3% of the occupied homes in Lewis County, Missouri (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesCodes & Standards Governing Furnace Installation in Lewis County, Missouri4 sourced rules and standards
What the Installation Looks Like
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.
Severe Weather Events in Lewis County
Weather patterns in Lewis County put real demands on heating equipment over its working life. A furnace sized and installed for local conditions holds up differently than one spec'd without that picture in mind.
65 severe weather events, 2015–2024. Source: NOAA National Centers for Environmental Information, Storm Events Database.