These are low efficiency furnaces.  This means you will have higher gas bills using one of these furnaces than if you select a higher efficiency model.

• These furnaces have standard burners with one flame level. The flame is either on at full capacity, or it is off.

• These furnaces will operate on low flame, and then automatically increase to high-flame when more heat is needed. (A two-stage thermostat is required which allows you to determine when high-flame is engaged.)
• The two stage burner will help maintain a more consistant temperature in your home, keeping your home at nearly the exact temperature you set your thermostat at.