FurnaceTallyInput BTU, output BTU, and the gap nobody explains.

FurnaceTally

Input BTU, output BTU, and the gap nobody explains.

SectionsLatest
Furnace BTU SizingInput against output, and how much of the label you actually get.360
AFUE & EfficiencyWhat 80% and 96% mean on a bill, and when the upgrade pays back.1
Venting & Combustion AirCategory I against Category IV, vent sizing, and why a high-efficiency swap changes the chimney.1
Fuel & Running CostGas, propane and electric compared per delivered BTU rather than per unit.1
Replacement CostFurnace, install, and the venting work that turns a quote into a project.204
  1. Water Dripping From the Furnace Vent — Normal on One Type, a Fault on the OtherVenting & Combustion Air · 3 min read

    The same drip is expected on one furnace and dangerous on another. Which one you have is decided by the vent material, and you can see it from across the room.

  2. Gas Bill Went Up After a New Furnace — Five Reasons That Are Not the FurnaceFuel & Running Cost · 3 min read

    Compare therms against degree days, not dollars against last year. Half of these complaints disappear the moment the weather is normalised out.

  3. New High-Efficiency Furnace Short Cycles — Usually the SizingAFUE & Efficiency · 3 min read

    The upgrade from 80% to 96% adds a fifth more heat from the same size box. Keep the input the same and you have just oversized the house by 20%.

Furnace BTU by area, climate and AFUE

360 calculations · Furnace BTU Sizing · browse all

Furnace replacement cost by state

204 calculations · Replacement Cost · browse all