Gas & FuelQuestion 63 of 110
A high-efficiency condensing furnace exhausts cool, wet flue gas under positive pressure. What venting category and material are appropriate?
a.Category I, type B vent
b.Category II, single-wall steel
c.Category IV, listed PVC/CPVC sealed vent
d.Category III, masonry chimney
Explanation
A condensing furnace is Category IV, operating at positive vent pressure with condensing (wet, acidic) flue gas, and it requires a listed, sealed PVC or CPVC vent that resists corrosion and holds pressure. A type B vent or masonry chimney would corrode and leak flue products. The condensate must also be drained and often neutralized.
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