Here are the essential components your furnace needs to function efficiently for many years:
Two-stage valves: The furnace will run at a high flow rate when first turned on and then at a decreasing flow rate to maintain the optimum temperature.
Sealed combustion: In addition to being more energy efficient, sealed combustion helps safeguard your home from deadly carbon monoxide.
Long warranty: If you get a more expensive, efficient model, you’ll have the assurance of a longer, more comprehensive guarantee. It is ideal if the heat exchangers come with a lengthy warrant.