CCS Flue Liner Types & Installation 2 — Questions and Answers
Question 1: What is the primary reason cast-in-place liners are preferred for irregularly shaped flues?
- They cure faster than other liner types
- They conform to the existing flue shape without requiring demolition (Correct answer)
- They are less expensive than all alternatives
- They require no chimney cap after installation
Correct answer: They conform to the existing flue shape without requiring demolition
Cast-in-place liners are poured or pumped directly into the existing flue, conforming to irregular shapes and filling voids without major demolition.
Question 2: Which NFPA standard governs the installation of factory-built chimneys and their liners?
- NFPA 31
- NFPA 54
- NFPA 211 (Correct answer)
- NFPA 101
Correct answer: NFPA 211
NFPA 211 is the Standard for Chimneys, Fireplaces, Vents, and Solid Fuel-Burning Appliances, covering liner installation requirements.
Question 3: A homeowner reports that their stainless steel liner shows heavy pitting after two years of use with an oil-fired appliance. What is the most likely cause?
- The liner was installed with the wrong orientation
- An incorrect alloy grade was used for oil appliance flue gases (Correct answer)
- The liner diameter was too large for the appliance
- The liner was not insulated during installation
Correct answer: An incorrect alloy grade was used for oil appliance flue gases
Oil appliances produce sulfuric acid condensate that requires a higher-grade alloy; using 316Ti or 316L instead of 304 stainless prevents pitting corrosion.
Question 4: When sizing a liner for a wood-burning fireplace, the cross-sectional area of the liner should generally be at least what fraction of the fireplace opening area?
- 1/4
- 1/8
- 1/10 (Correct answer)
- 1/12
Correct answer: 1/10
A common guideline is that the flue cross-sectional area should be at least 1/10 of the fireplace opening area to ensure adequate draft.
Question 5: What does the term 'listed' mean when applied to a flexible stainless steel liner system?
- The liner appears on a local building department approved list
- The liner has been tested and certified by a recognized testing laboratory (Correct answer)
- The liner meets the minimum gauge requirement only
- The liner is registered with the CSIA
Correct answer: The liner has been tested and certified by a recognized testing laboratory
A listed product has been evaluated by an accredited testing laboratory such as UL and meets published safety and performance standards.
Question 6: Which installation practice is required when a flexible stainless liner passes through a combustible floor or ceiling?
- The liner must be coated with intumescent paint
- An approved firestop spacer must be installed at the penetration (Correct answer)
- The liner must be wrapped with aluminum foil tape
- The liner must be reduced in diameter at the penetration point
Correct answer: An approved firestop spacer must be installed at the penetration
Firestop spacers maintain required clearances and prevent flame spread where the liner penetrates combustible building materials.
Question 7: A terra cotta tile liner section that has spalled on its interior surface but has no cracks should be classified as:
- Serviceable with no action needed
- Requiring monitoring at the next annual inspection
- Defective and requiring repair or replacement before use (Correct answer)
- Acceptable only for gas appliances
Correct answer: Defective and requiring repair or replacement before use
Spalling reduces liner wall thickness and can expose combustible materials to heat and gases, making the liner defective and unsafe for continued use.
CCS Flue Liner Types & Installation 2
What is the primary reason cast-in-place liners are preferred for irregularly shaped flues?