How do furnaces work?

A furnace, as part of a central heating and cooling system, converts fuel into heat, then uses a blower to circulate warm air throughout your house. In summer, the furnace works with your heat pump or air conditioner to draw in warm air from your house and recirculate the newly cooled air. The main components to a natural gas furnace include burners and heat exchanger, blower and controls.

Should I repair or replace my furnace?

We recommend replacing your furnace if it’s 15 years old or more, has an AFUE of 80% or less, needs frequent repairs, is declining in performance or your energy costs are rising.

If you do need to replace your furnace, consider the AFUE efficiency rating, heating stages, noise level and cost. Every furnace is going to age differently based on location, maintenance, build quality and other factors. We can give you a custom evaluation and recommend the right solution for you.


Annual Fuel Utilization Efficiency, measured in a percentage. A higher percentage means higher efficiency.


Some furnaces have two stages of heat, similar to a reading lamp that has a lower setting and a brighter setting. Others have modular stages of heat, similar to a dimmer light switch that has more flexibility.

S9X1 Gas Furnace

Trane’s most affordable high energy efficient furnace keeps your home and budget comfortable.

  • High-efficiency rating of up to 96% Annual Fuel Utilization Efficiency (AFUE)
  • Tested materials and components for dependable performance

S9X2 Gas Furnace

The new S9X2 furnace offers two stages of gas heat for comfort in cold weather, and a CTM blower for maximum efficiency in warm weather, while maintaining the quality and reliability that Trane is known for.


S9V2-VS Gas Furnace

Trane’s quietest furnace combines high energy efficiency with noise reducing technology for complete comfort

  • Patented Vortica™II variable speed blower and variable speed draft inducer delivers maximum efficiency with very little sound
  • ENERGY STAR rated furnace rated up to 97% Annual Fuel Utilization Efficiency (AFUE)
  • Comfort-R™ enhanced dehumidification mode reduces home humidity level in summer

XC95 Gas Furnace

Trane’s most energy efficient furnace provides the ultimate comfort and greater energy savings

  • Up to 97.3% Annual Fuel Utilization Efficiency (AFUE)
  • Variable-speed blower motor adjusts speed to provide a consistent flow of warm, comfortable air with quiet operation
  • Advanced ComfortLink™ II communicating technology constantly calibrates itself for optimal performance year after year

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