Which characteristic is typical of condensing boilers?

The characteristic that indicates a typical feature of condensing boilers is associated with their higher upfront cost but better efficiency. Condensing boilers are designed to extract additional heat from the flue gases by cooling them down to below the condensation point, which allows for more efficient heating. This process can lead to efficiencies exceeding 90%, which is significantly better than traditional non-condensing models.

The initial investment for condensing boilers is generally higher due to their advanced technology and the materials required to handle condensation. However, this higher cost is often justified over time through energy savings and reduced fuel consumption. As such, they are considered a more economical choice in the long run, despite the steeper purchase price.

The other options present characteristics that do not accurately reflect condensing boilers. Increased flue gas temperatures are typically found in non-condensing systems, while the use of non-renewable energy exclusively does not pertain to condensing technology since they can be compatible with various fuel sources. Finally, lower efficiency than traditional boilers contradicts the fundamental design of condensing boilers, which aim to provide greater efficiency through their innovative processes.