Which component is commonly associated with high-efficiency furnaces and is not present in many mid-efficiency models?

Which component is commonly associated with high-efficiency furnaces and is not present in many mid-efficiency models?

• A. Secondary heat exchanger
• B. Pilot light
• C. Non-condensing vent
• D. Open combustion chamber

Answer: (A)

High-efficiency (condensing) furnaces extract more heat by using a second stage of heat transfer, a secondary heat exchanger. This extra exchanger captures additional energy from the combustion gases as they cool and condense, which raises the unit’s efficiency to about 90%+ and beyond. Mid-efficiency models typically rely on a single heat exchanger and non-condensing venting, so they don’t include this second exchanger. That’s why the secondary heat exchanger is the component commonly associated with high-efficiency furnaces and not present in many mid-efficiency models.

High-efficiency (condensing) furnaces extract more heat by using a second stage of heat transfer, a secondary heat exchanger. This extra exchanger captures additional energy from the combustion gases as they cool and condense, which raises the unit’s efficiency to about 90%+ and beyond. Mid-efficiency models typically rely on a single heat exchanger and non-condensing venting, so they don’t include this second exchanger. That’s why the secondary heat exchanger is the component commonly associated with high-efficiency furnaces and not present in many mid-efficiency models.