Keeping the Furnace Draft

What is required to maintain draft in a furnace?

A. Positive pressure both outside and inside the furnace.

B. Positive pressure outside of the furnace and negative pressure inside the furnace.

C. Negative pressure on the outside of the furnace and positive pressure inside the furnace.

D. Negative pressure both outside and inside the furnace.

Answer:

C. Negative pressure on the outside of the furnace and positive pressure inside the furnace.

To maintain draft in a furnace, there should be negative pressure on the outside and positive pressure inside. This arrangement ensures that air or gases flow from areas of high pressure (inside the furnace) to areas of low pressure (outside the furnace).

Having negative pressure on the outside of the furnace helps to pull in fresh air, while positive pressure inside the furnace pushes the air or gases out, creating the necessary draft for proper ventilation and combustion.