Which category of gas-fired appliance does not create condensate?

• A. Category 2
• B. Category 1
• C. Category 3
• D. Condensing

Answer: (B)

Condensation occurs when the flue gases cool below the dew point of water, turning water vapor into liquid. The non-condensing category keeps the flame exhaust hot enough that the water stays in vapor form, so no condensate forms in the venting system. This category uses either natural draft or a venting arrangement that maintains high exhaust temperatures, unlike condensing appliances that deliberately cool the gases to recover heat and produce liquid condensate that must be drained. So, the non-condensing category is the one that does not create condensate.