CCP CCP Chimney Draft & Combustion Principles

Question 1

What is the primary driving force behind chimney draft?

Accepted Answer

Temperature differential between flue gases and outside air

Answer

Chimney draft is primarily driven by the temperature differential between hot flue gases and cooler outside air, creating a buoyancy-based pressure difference.

Question 2

What unit is typically used to measure chimney draft pressure?

Accepted Answer

Pascals or inches of water column

Answer

Chimney draft pressure is measured in Pascals or inches of water column (in. WC) because draft is a very small pressure difference requiring sensitive units.

Question 3

Which condition is most likely to cause a chimney to backdraft?

Accepted Answer

Negative indoor air pressure relative to outside

Answer

Backdrafting occurs when the home has negative indoor pressure — often from exhaust fans or tight construction — pulling flue gases back into the living space.

Question 4

What is the minimum natural draft typically required for proper residential appliance operation?

Accepted Answer

0.01 to 0.05 inches of water column

Answer

Most residential appliances require a minimum natural draft of 0.01 to 0.05 inches of water column for proper combustion and safe venting.

Question 5

How does chimney height affect draft performance?

Accepted Answer

Taller chimneys generally produce stronger draft

Answer

Taller chimneys create a greater column of buoyant hot gases, increasing the pressure difference and strengthening natural draft.

CCP - Certified Chimney Professionals Practice Test

CCP - Certified Chimney Professionals Practice Test

CCP CCP Chimney Draft & Combustion Principles