CFESA Gas Chapter 4 Exam Questions
with Complete Solutions
What is the difference between a vent and a flue? - -A flue removes
byproducts from the combustion chamber. A vent removes products from
the room to the outdoors.
- What are the two primary functions of the flue? - -Remove combustion
byproducts from the combustion chamber, and to create a draft to pull in
secondary air.
- How critical is the sizing of the flue? Why? - -Very. Too small and it wil not
remove all the byproducts, if it is too large the vapors will start to condense.
- Can a vent pipe be connected directly to the flue on a piece of gas
equipment? - -No
- What is the function of a draft hood? - -To allow the flue to determine the
draft
- When should a draft hood be used? - -Anytime a vent pipe is connected to
a piece of equipment
- What is a downdraft? - -Air entering down the vent pipe, usually caused by
cold outside temperatures or high winds
- How can a downdraft create equipment problems? - -It can blow out pilots
and create problems getting a draft started in the combustion chamber.
- What type of vent pipe should be used in commercial applications? - -Type
B double wall
- Why is it necessary to use double wall vent pipe? - -It keeps the flue
products from condensing and provides an insulation barrier to prevents the
hot flue gas from starting a fire if something lays against it
- What size vent pipe will be needed for a piece of equipment rated at
160,000 Btu, if it is located 10 feet away from the roof opening, and in a
room with a 10 foot ceiling? - -5 inch
- What size vent pipes are needed for two ovens, each rated at eighty
thousand Btu's, if the roof is 10 feet high, and the flue connector rise is 2
feet on each of them? - -Connectors are 5 inches, common vent is 6 inch.
with Complete Solutions
What is the difference between a vent and a flue? - -A flue removes
byproducts from the combustion chamber. A vent removes products from
the room to the outdoors.
- What are the two primary functions of the flue? - -Remove combustion
byproducts from the combustion chamber, and to create a draft to pull in
secondary air.
- How critical is the sizing of the flue? Why? - -Very. Too small and it wil not
remove all the byproducts, if it is too large the vapors will start to condense.
- Can a vent pipe be connected directly to the flue on a piece of gas
equipment? - -No
- What is the function of a draft hood? - -To allow the flue to determine the
draft
- When should a draft hood be used? - -Anytime a vent pipe is connected to
a piece of equipment
- What is a downdraft? - -Air entering down the vent pipe, usually caused by
cold outside temperatures or high winds
- How can a downdraft create equipment problems? - -It can blow out pilots
and create problems getting a draft started in the combustion chamber.
- What type of vent pipe should be used in commercial applications? - -Type
B double wall
- Why is it necessary to use double wall vent pipe? - -It keeps the flue
products from condensing and provides an insulation barrier to prevents the
hot flue gas from starting a fire if something lays against it
- What size vent pipe will be needed for a piece of equipment rated at
160,000 Btu, if it is located 10 feet away from the roof opening, and in a
room with a 10 foot ceiling? - -5 inch
- What size vent pipes are needed for two ovens, each rated at eighty
thousand Btu's, if the roof is 10 feet high, and the flue connector rise is 2
feet on each of them? - -Connectors are 5 inches, common vent is 6 inch.
