What is the purpose of a condensate drain in a high-efficiency gas furnace?

The purpose of a condensate drain in a high-efficiency gas furnace is to remove excess moisture produced during combustion. High-efficiency furnaces operate at lower temperatures and extract more heat from the combustion process, which leads to the production of water vapor as a byproduct. This water vapor condenses into liquid form and must be drained from the system to prevent damage or operational issues. If this condensate is not properly channeled away, it could lead to rust, corrosion, or water accumulation within the furnace or surrounding areas, leading to further complications.

The other options address different functions of furnace components. For instance, supplying gas to the burners pertains to the gas delivery system, while circulating warm air is relevant to the blower and ductwork. Venting exhaust gases outside is related to the flue or venting system, which is crucial for safe operation but does not address the moisture issue managed by the condensate drain. Understanding the specific role of each component helps in maintaining the overall efficiency and safety of the gas furnace.