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Trane
100,000 BTU Gas Furnace
Trane 80% AFUE, Single-Stage, Upflow/Downflow/Horizontal, 21" Cabinet | S8X1C100M5PSC
$2,055.99
A furnace heats your home by burning gas or oil and blowing warm air through your ducts. Unlike air conditioners, furnaces are sized by heating output in BTU rather than tons — and the right number depends on your climate and home, not just square footage. Browse gas furnaces by BTU, or oil furnaces below.
185 products
Trane
Trane 80% AFUE, Single-Stage, Upflow/Downflow/Horizontal, 21" Cabinet | S8X1C100M5PSC
Trane
Trane 80% AFUE, Two-Stage, Upflow/Downflow/Horizontal, 21" Cabinet | S8X2C100M5PSC
Trane
Trane 80% AFUE, Two-Stage Variable Speed, Upflow/Downflow/Horizontal, 21" Cabinet | S8V2C100M5PCB
Trane
Trane 96% AFUE, Single-Stage, Upflow/Left/Right, 21" Cabinet | S9X1C100U5PSB
Trane
Trane 96% AFUE, Two-Stage, Upflow/Left/Right, 21" Cabinet | S9X2C100U5PSB
Trane
Trane 97% AFUE, Two-Stage Variable Speed, Upflow/Horizontal, 2-3 Ton Airflow, 21" Cabinet | S9V2C100U4VSB
Trane
Trane 97% AFUE, Two-Stage Variable Speed, Upflow/Horizontal, 3-4 Ton Airflow, 21" Cabinet | S9V2C100U5VSB
Ruud
Ruud 80% AFUE, Upflow/Horizontal, Constant-Torque ECM, 4.5 Ton Airflow, 21" Cabinet, Manufactured Housing | R801TA100521MSA
Ruud
Ruud 80% AFUE, Upflow/Horizontal, Constant-Torque ECM, 4.5 Ton Airflow, 21" Cabinet | R801T1005A21UHSNA
Ruud
Ruud 80% AFUE, Upflow/Horizontal, Variable-Speed ECM, 5 Ton Airflow, 21" Cabinet | R801V1005A21UHSCA
Trane
Trane 80% AFUE, Single-Stage, Upflow/Downflow/Horizontal, 24.5" Cabinet | S8X1D120M5PSC
Trane
Trane 80% AFUE, Two-Stage, Upflow/Downflow/Horizontal, 24.5" Cabinet | S8X2D120M5PSC
Trane
Trane 96% AFUE, Single-Stage, Upflow/Left/Right, 24.5" Cabinet | S9X1D120U5PSB
Trane
Trane 96% AFUE, Two-Stage, Upflow/Left/Right, 24.5" Cabinet | S9X2D120U5PSB
Trane
Trane 97% AFUE, Two-Stage Variable Speed, Upflow/Horizontal, 3-4 Ton Airflow, 24.5" Cabinet | S9V2D120U5VSB
Ruud
Ruud 80% AFUE, Upflow/Horizontal, Constant-Torque ECM, 5 Ton Airflow, 24.5" Cabinet | R801T1255A24UHSNA
Ruud
Ruud 80% AFUE, Upflow/Horizontal, Variable-Speed ECM, 5 Ton Airflow, 24.5" Cabinet | R801V1255A24UHSCA
Trane
Trane 80% AFUE, Single-Stage, Upflow/Downflow/Horizontal, 14.5" Cabinet | S8X1A026M2PSC
Trane
Trane 80% AFUE, Single-Stage, Upflow/Downflow/Horizontal, 14.5" Cabinet | S8X1A040M3PSC
Trane
Trane 80% AFUE, Single-Stage, Upflow/Downflow/Horizontal, 17.5" Cabinet | S8X1B040M2PSC
Trane
Trane 80% AFUE, Two-Stage, Upflow/Downflow/Horizontal, 14.5" Cabinet | S8X2A040M3PSC
Trane
Trane 80% AFUE, Two-Stage Variable Speed, Upflow/Downflow/Horizontal, 14.5" Cabinet | S8V2A040M3PCB
Trane
Trane 96% AFUE, Single-Stage, Upflow/Left/Right, 17.5" Cabinet | S9X1B040U3PSB
Trane
Trane 96% AFUE, Two-Stage, Upflow/Left/Right, 17.5" Cabinet | S9X2B040U3PSB
Ruud
Ruud 80% AFUE, Upflow/Horizontal, Constant-Torque ECM, 3 Ton Airflow, 14" Cabinet | R801T0503A14UHSNA
Ruud
Ruud 80% AFUE, Upflow/Horizontal, Variable-Speed ECM, 3 Ton Airflow, 14" Cabinet | R801V0503A14UHSCA
Trane
Trane 80% AFUE, Single-Stage, Upflow/Downflow/Horizontal, 17.5" Cabinet | S8X1B060M4PSC
Trane
Trane 80% AFUE, Two-Stage, Upflow/Downflow/Horizontal, 17.5" Cabinet | S8X2B060M4PSC
Trane
Trane 80% AFUE, Two-Stage Variable Speed, Upflow/Downflow/Horizontal, 17.5" Cabinet | S8V2B060M4PCB
Trane
Trane 96% AFUE, Single-Stage, Upflow/Left/Right, 17.5" Cabinet | S9X1B060U4PSB
Trane
Trane 96% AFUE, Two-Stage, Upflow/Left/Right, 17.5" Cabinet | S9X2B060U4PSB
Trane
Trane 97% AFUE, Two-Stage Variable Speed, Upflow/Horizontal, 1.5-2.5 Ton Airflow, 17.5" Cabinet | S9V2B060U3VSB
Trane
Trane 97% AFUE, Two-Stage Variable Speed, Upflow/Horizontal, 2-3 Ton Airflow, 17.5" Cabinet | S9V2B060U4VSB
Ruud
Ruud 80% AFUE, Upflow/Horizontal, Constant-Torque ECM, 3.5 Ton Airflow, 17.5" Cabinet | R801T0754A17UHSNA
Ruud
Ruud 80% AFUE, Upflow/Horizontal, Constant-Torque ECM, 4 Ton Airflow, 21" Cabinet | R801T0754A21UHSNA
Ruud
Ruud 80% AFUE, Upflow/Horizontal, Variable-Speed ECM, 4 Ton Airflow, 17.5" Cabinet | R801V0754A17UHSCA
Ruud
Ruud 80% AFUE, Upflow/Horizontal, Variable-Speed ECM, 5 Ton Airflow, 21" Cabinet | R801V0755A21UHSCA
Trane
Trane 80% AFUE, Single-Stage, Upflow/Downflow/Horizontal, 17.5" Cabinet | S8X1B080M4PSC
Trane
Trane 80% AFUE, Single-Stage, Upflow/Downflow/Horizontal, 21" Cabinet | S8X1C080M5PSC
Trane
Trane 80% AFUE, Two-Stage, Upflow/Downflow/Horizontal, 17.5" Cabinet | S8X2B080M4PSC
Furnace sizing is about matching heat output to your home's heat loss. Too small and it can't keep up on the coldest nights; too large and it short-cycles, wasting fuel and wearing components. Colder climates need more BTU per square foot than mild ones, which is why a heating load calculation beats a rule of thumb.
Also weigh:
Not sure what BTU output your home needs? Send us the details and we'll size it →
Furnaces are sized by heating output in BTU. The right size depends on your climate and your home's heat loss — a heating load calculation is accurate, while square-footage rules of thumb (roughly 30–60 BTU per sq ft depending on region) only get you in the ballpark.
AFUE (Annual Fuel Utilization Efficiency) is the share of fuel a furnace converts to usable heat. An 80% AFUE furnace turns 80% of its fuel into heat; high-efficiency condensing furnaces reach 90–98%.
A 90%+ (condensing) furnace extracts more heat from the same fuel and vents through PVC rather than metal flue, lowering fuel bills. It costs more up front and needs a condensate drain, so the payback depends on your climate and fuel prices.
Yes. Gas furnaces run on natural gas or propane (often with a conversion kit), and we also carry oil furnaces for homes on heating oil. Choose based on the fuel available at your property.
The furnace blower moves air for both heating and cooling, so it should be paired with a compatible coil and AC and sized for adequate airflow. Mismatched components hurt efficiency and comfort.