Venting & Combustion Air

Category I against Category IV, vent sizing, and why a high-efficiency swap changes the chimney.

1 article

• Water Dripping From the Furnace Vent — Normal on One Type, a Fault on the Other

  The same drip is expected on one furnace and dangerous on another. Which one you have is decided by the vent material, and you can see it from across the room.