High efficiency gas furnaces may use ______ pumps.

High efficiency gas furnaces may use ______ pumps.

• A. condensate
• B. circulating
• C. fuel
• D. air

Answer: (A)

High efficiency gas furnaces produce liquid condensate from the combustion gases as they cool in a secondary heat exchanger. That condensate collects in a trap and must be moved away to prevent overflow and corrosion, so a condensate pump is used to lift and discharge the water to a proper drain. This pumping is a direct result of the condensing design, which differentiates high-efficiency units from older non-condensing models. Other pumps mentioned don’t fit this setup: circulating pumps are for circulating hot water in radiant or hydronic systems, fuel pumps aren’t part of typical natural gas furnaces, and air pumps aren’t used for handling combustion condensate.

High efficiency gas furnaces produce liquid condensate from the combustion gases as they cool in a secondary heat exchanger. That condensate collects in a trap and must be moved away to prevent overflow and corrosion, so a condensate pump is used to lift and discharge the water to a proper drain. This pumping is a direct result of the condensing design, which differentiates high-efficiency units from older non-condensing models. Other pumps mentioned don’t fit this setup: circulating pumps are for circulating hot water in radiant or hydronic systems, fuel pumps aren’t part of typical natural gas furnaces, and air pumps aren’t used for handling combustion condensate.