CCS Ventilation & Draft Systems 3

Question 1

A masonry chimney liner is found to be cracked and spalled. Which primary hazard does this pose to the ventilation system?

Accepted Answer

Infiltration of combustion gases into living spaces

Answer

Cracks in the liner allow carbon monoxide and other combustion gases to leak through the chimney wall into the building structure or living spaces.

Question 2

What is 'wind-induced downdraft,' and which chimney feature most effectively prevents it?

Accepted Answer

Downward air movement caused by wind turbulence; prevented by a proper chimney cap design

Answer

Wind-induced downdraft occurs when wind turbulence forces air down the chimney; a properly designed cap with wind-deflecting geometry redirects airflow to prevent this.

Question 3

When sizing a flue for a wood-burning fireplace, the cross-sectional area of the flue should be approximately what fraction of the fireplace opening area?

Accepted Answer

1/12 to 1/15

Answer

For a wood-burning fireplace, the flue cross-sectional area should be approximately 1/12 to 1/15 of the fireplace opening area to maintain proper draft without oversizing.

Question 4

Which condition describes 'short cycling' in relation to chimney draft?

Accepted Answer

Combustion gases cooling and falling before reaching the top of the chimney

Answer

Short cycling in draft context refers to cooled, heavy flue gases that lose buoyancy and descend before exiting, interrupting continuous upward flow.

Question 5

A gas appliance vent connector should not exceed what maximum horizontal run per NFPA 54 guidelines?

Accepted Answer

50% of the vertical height of the chimney or vent

Answer

NFPA 54 limits the horizontal vent connector run to no more than 75% of the vertical height; however, the common practical rule applied in many jurisdictions is no more than 50% for optimal draft.

(CCS) Certified Chimney Sweeper Practice Test

(CCS) Certified Chimney Sweeper Practice Test

CCS Ventilation & Draft Systems 3