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WorksheetsChimney/Flue phase 3
Total questions: 58
Worksheet time: 29mins
What are the two operating principles for any chimney or flue system?
Heat the air and cool the combustion gases.
Remove combustion products to the outside and draw in air for combustion.
Filter the air and recycle the combustion gases.
Produce electrical energy and heat water.
On what principle do chimney or flue systems work to create a pressure differential called 'updraft'?
The freezing of hot gases.
The condensation of hot gases.
The rise of hot gases, creating a pressure difference through convection.
The thermal expansion of cold air.
What is the basic concept of a chimney or flue system?
To filter the air within a room
To create an up draught to get rid of the fumes
To heat the surrounding environment
To circulate cold air
Which of the following is a type of flue design?
Forced draught
Natural draught
Electrical draught
Solar draught
What other flue design apart from natural draught can you identify?
Room sealed
closed vent
Mechanical sealed
Environmentally sealed
What is the simplest design of all flues that relies on heat rising to create the up draught?
Forced draught flue
Chimney flue
Open flue
Balanced flue
Open flues can be of which types?
Natural draught or forced draught
Electric draught or gas draught
Indoor draught or outdoor draught
Mechanical draught or manual draught
Where is the air for combustion taken from in an appliance with an open flue?
From outside the building
From the combustion chamber
From the room in which the appliance is located
From the secondary flue
How are the products of combustion removed in an appliance with an open flue?
Through a vent in the room
Up the flue by natural draught
Directly outside through a side vent
By a mechanical extractor
What must be supplied to the room and appliance from outside via a vent in an open flue system?
Natural gas
Electricity
Air for combustion
Water for cooling
What is the purpose of the fan positioned by the manufacturer in an open flue with forced draught?
To cool down the appliance
To create a positive up draught by blowing the products of combustion up the flue
To filter the products of combustion
To generate electricity for the appliance
What is the function of room sealed (balanced) flues in appliances?
They allow air to flow from the room into the appliance for combustion.
They draw air for combustion directly from outside and do not let it enter the room.
They release combustion gases into the room for better air circulation.
They use room air for combustion and release it back into the room.
Why are room sealed flued appliances considered safer than open-flued appliances?
Because they use less energy for combustion.
Because they can operate without electricity.
Because they do not discharge combustion products into the room.
Because they are easier to install.
What are the two types of room sealed (balanced) flues?
Electric and Gas
Natural draught and Fan assisted (forced)
Indoor and Outdoor
Horizontal and Vertical
Where are the combustion air inlet and the products of combustion outlet situated in a room sealed natural draught system?
Inside the building in different positions
Outside the building in the same position
Inside the building in the same position
Outside the building in different positions
How are the products of combustion evacuated from the building in a room sealed natural draught system?
Through a separate duct from the combustion air duct
Through the same duct as the combustion air duct
Through natural ventilation without a duct
Through a duct that runs through the combustion air duct
How does a room sealed fan assisted flue work compared to a natural draught flue?
It uses natural convection to evacuate products.
It is powered by a manufacturer's fan to ensure evacuation of products.
It relies solely on wind power for evacuation.
It uses a larger flue to improve the evacuation process.
What is one advantage of a room sealed fan assisted flue over a natural draught flue?
It requires more space for installation.
It can only be positioned in a few specific places.
It is much larger and more visible.
It can be positioned in many more places than the natural draught flue.
How many different versions of the fan assisted boiler are there?
One
Two
Three
Four
Where is the fan positioned in the first version of the fan assisted boiler?
On the fresh air inlet
On the combustion product's outlet from the heat exchanger
Inside the burner
Outside the case
What kind of pressure does the fan create in the first version of the fan assisted boiler?
Positive pressure (blowing)
Negative pressure (sucking)
No pressure change
Variable pressure
Where is the fan positioned in the second version of the fan assisted boiler?
On the fresh air inlet
On the combustion product's outlet from the heat exchanger
Inside the burner
Outside the case
What kind of pressure does the fan create in the second version of the fan assisted boiler?
Positive pressure (blowing)
Negative pressure (sucking)
No pressure change
Variable pressure
Which design do modern condensing boilers use?
The first version with negative pressure
The second version with positive pressure
A design without a fan
A design with variable pressure
What is the minimum length that the primary flue must be on open flued appliances?
At least 500 mm
At least 600 mm
At least 700 mm
At least 800 mm
What is the function of the draught diverter?
To increase the up-draught
To moderate pressure fluctuations in the flue system
To extend the length of the flue
To filter the flue gases
Which of the following is NOT a function of the draught diverter?
Diverting down-draught away from the burner
Diluting the flue gases
Reducing the pull of the secondary flue
Increasing carbon dioxide content
Secondary flues should be constructed of what type of material?
Single-wall insulated material
Twin-wall insulated material
Non-insulated material
Triple-wall insulated material
What is the job of the terminal in an open flue system?
To filter the flue gases
To increase the efficiency of the flue
To help the flue gases discharge to atmosphere and prevent external elements from entering
To regulate the temperature of the flue gases
How does the design and installation of chimney and flue systems affect their function?
They do not affect the function of air intake or the dispersion of combustion products.
They only affect the aesthetic appeal of the systems without influencing their function.
They affect both the function of air intake and the safe dispersion of the products of combustion.
They only affect the function of air intake but not the dispersion of the products of combustion.
What needs to be considered carefully in relation to chimney/flue systems?
The color and design patterns of the chimney/flue systems.
The cost-effectiveness of the chimney/flue systems.
The factors that affect the layout of the chimney/flue systems.
The brand of the chimney/flue systems.
According to the manufacturer's instructions, how should all chimneys and flues be routed to ensure the best flow of gases?
With as many bends as possible to fit the building design
Following the path with the least number of bends
With a minimum of a 90° angle at each bend
In a zigzag pattern to increase surface area
What is the minimum angle that should be kept if bends are required in chimneys and flue systems?
30°
45°
60°
90°
What does the effective height of a chimney or flue system take into account?
The physical measured height only
The color and material of the chimney
The frictional resistance encountered en route
The external temperature and weather conditions
For a flue to work efficiently, how quickly should the temperature rise and remain?
Slowly and fluctuate often
Quickly and remain constant
Quickly and then drop rapidly
Slowly and remain low
What can happen when the flue is cool and the flue gases move slowly?
The flue gases can create a strong draft
The flue gases can exit more efficiently
The flue gases can create condensation and the potential of flue gas spillage
The flue gases can heat up the flue more quickly
How long can it take for the chimney/flue to heat up fully when the flue is heated?
1–2 minutes
5–10 minutes
15–20 minutes
30–60 minutes
What is the required velocity for the safe evacuation of flue gases according to the document?
3m/s
6m/s
9m/s
12m/s
Terminals need to have an opening that is how many times the cross-sectional area of the flue itself?
Equal to the cross-sectional area of the flue
Twice the cross-sectional area of the flue
Three times the cross-sectional area of the flue
Four times the cross-sectional area of the flue
According to the document, where should a terminal NOT be located?
Where it will not be a nuisance
Outside a pressure zone
Inside a pressure zone
Near the building entrance
What is the minimum flue height termination for a pitched roof with a net input of less than 70 kW?
600 mm above the roof line
250 mm above the roof line
At ridge, or 600 mm above or at least 1.5 m measured horizontally to the roof line
1000 mm above the roof line
For a flat roof with a net input of less than 70 kW, how far must the flue be above the roof line if it is within 2.5 m of a nearby structure?
600 mm above that point
250 mm above the roof line
1000 mm above that point
1.5 m measured horizontally to the roof line
What is the required flue height termination for a flat roof with a net input of more than 70 kW?
600 mm above the roof line
250 mm above the roof line
At ridge, or 600 mm above or at least 1.5 m measured horizontally to the roof line
1000 mm above the roof line
If a flue on a pitched roof with a net input of less than 70 kW is within 1.5 m of a nearby structure, how high must the flue be raised above that point?
600 mm above that point
250 mm above the roof line
1000 mm above that point
1.5 m measured horizontally to the roof line
What does the layout and features of chimney and flue construction depend on?
The type of fuel used
The material they are constructed from
The height of the building
The preferences of the homeowner
Which of the following is NOT a type of rigid chimney?
Brick and masonry
Pre-cast blocks
Metallic flues
Wooden beams
What is a component of a flexible liner system for chimneys?
Concrete lining
Metallic flues
Flexible liners
Stone tiles
What size were chimneys installed prior to 1966?
175mm round
200mm²
9" x 9" or 225mm x 225mm
175mm x 200mm
After 1966, what materials were chimneys commonly made of?
Wood and metal
Clay, pumice, or concrete
Plastic and asbestos
Steel and brick
Why were larger chimneys considered unsuitable for gas appliances after 1966?
They were too expensive to produce
They would cause the velocity of the flue gases to slow down too much
They were difficult to install
They were not aesthetically pleasing
What is one identified problem with pre-cast flue blocks?
They are too lightweight.
They have excellent 'pull'.
They can be quite poor in 'pull'.
They are incompatible with all house builds.
Pre-cast flue blocks are made from which material?
Plastic
Concrete
Metal
Wood
Can all gas appliances be installed on pre-cast flue block systems?
Yes, without exceptions.
Only if modified.
No, not all gas appliances can be installed.
Yes, but only with manufacturer's consent.
What should always be checked before installing a flue system?
The house design plans.
The local weather conditions.
The manufacturer's instructions.
The color compatibility with the house.
What is the main purpose of using a twin wall in flue systems?
To enhance the visual appeal of the chimney
To create a barrier against condensation and heat
To reduce the cost of chimney construction
To increase the airflow within the chimney
Which type of flue system is suitable for lining a chimney and sometimes used with Agas and stoves?
Flexible non-metallic
Twin wall
Single wall
Triple wall
What material is a high-grade single wall flue system typically made from?
Copper
Aluminum
Stainless steel
Plastic
Can a rigid-metallic single wall flue system be enameled?
Yes, always
No, never
Sometimes
Only if it is a twin wall system
