In what situation might a technician recommend upgrading to a more efficient model?

Upgrading to a more efficient gas furnace is often recommended when the existing model has an Annual Fuel Utilization Efficiency (AFUE) rating below 80%. An AFUE rating indicates how effectively a furnace converts the energy in its fuel into heat. Furnaces with a lower rating are typically less efficient, meaning they waste more energy, which can lead to higher utility bills and a larger carbon footprint. In contrast, modern furnaces often have AFUE ratings that exceed 90%, offering significant energy savings and improved performance. Therefore, recommending an upgrade is sensible in this scenario as it can lead to cost savings over time and improved heating comfort for the homeowner.