CCS CCS Fireplace Anatomy & Components 1 — Questions and Answers
Question 1: What is the function of the smoke shelf in a masonry fireplace?
- To hold the damper assembly in place
- To catch falling debris and rain and prevent downdrafts from pushing smoke into the room (Correct answer)
- To support the firebox floor
- To direct combustion air to the fire
Correct answer: To catch falling debris and rain and prevent downdrafts from pushing smoke into the room
The smoke shelf sits just above the throat damper and acts as a barrier that catches falling debris and deflects cold downdraft air upward so it mixes with rising hot gases.
Question 2: Which part of the fireplace is referred to as the 'throat'?
- The firebox opening facing the room
- The narrow passage between the top of the firebox and the smoke chamber where the damper is located (Correct answer)
- The base of the flue liner
- The ash dump opening in the firebox floor
Correct answer: The narrow passage between the top of the firebox and the smoke chamber where the damper is located
The throat is the constricted opening at the top of the firebox, just above the fireplace opening, where the throat damper controls airflow into the smoke chamber.
Question 3: The smoke chamber is located:
- Below the firebox floor
- Between the throat damper and the base of the flue liner (Correct answer)
- Inside the flue liner above the crown
- Behind the fireback in the firebox
Correct answer: Between the throat damper and the base of the flue liner
The smoke chamber is the expanding space above the throat that compresses gases and transitions them upward into the flue liner.
Question 4: What is the recommended parge coat material for smoke chambers according to NFPA 211?
- Standard mortar mix at any thickness
- A 1/2-inch or greater layer of listed refractory mortar to seal and smooth the smoke chamber walls (Correct answer)
- Portland cement with sand only
- Fireclay mixed with water
Correct answer: A 1/2-inch or greater layer of listed refractory mortar to seal and smooth the smoke chamber walls
NFPA 211 recommends parging smoke chambers with at least 1/2 inch of listed refractory mortar to seal corbeled joints and create a smooth, efficient surface.
Question 5: The fireback is the rear wall of the firebox and its primary function is to:
- Prevent creosote from forming
- Reflect radiant heat into the room and protect the masonry behind the fire (Correct answer)
- Support the smoke shelf above
- Seal the ash pit below
Correct answer: Reflect radiant heat into the room and protect the masonry behind the fire
The fireback reflects heat forward into the room and protects the masonry from direct flame exposure, improving both heating efficiency and durability of the fireplace.
Question 6: An ash dump is located in the firebox floor and connects to:
- The smoke chamber above
- An ash pit below the firebox where ash can be collected and removed from outside (Correct answer)
- The combustion air intake vent
- The clean-out door in the flue liner
Correct answer: An ash pit below the firebox where ash can be collected and removed from outside
The ash dump is a small hinged door in the firebox floor through which ash falls into a sealed ash pit below, usually accessed via a clean-out door at the base of the chimney exterior.
CCS CCS Fireplace Anatomy & Components 1
What is the function of the smoke shelf in a masonry fireplace?