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WorksheetsDomestic Gas Flues/Chimneys Quiz Quiz
Total questions: 41
Worksheet time: 21mins
An appliance with a B11 flue system is described as?
Open flued, natural draught, with fan upstream of heat exchanger.
Open flued, fanned draught, with fan downstream of heat exchanger.
Open flued, natural draught, with draught diverter.
Open flued, natural draught, without draught diverter (closed flue)
Open flue, Natural draught Chimney Systems
The purpose of a draught diverter is?
To direct any downdraught away from the combustion chamber.
To direct carbon monoxide into the flue.
To prevent downdraught.
To prevent condensation from entering the appliance.
An open flued chimney should rise vertically by ………. mm before any change of direction?
300 mm.
600 mm.
900 mm.
1200 mm.
Any bends used on a chimney should not exceed?
35°.
45°.
60°.
90°.
The minimum cross sectional area of a chimney for a new gas fire is?
120 mm².
1200 mm².
12000 mm².
120000 mm².
Which size of opening within a pre-cast flue block would be unsuitable for a gas fire?
90 mm x 185 mm.
100 mm x 165 mm.
70 mm x 250 mm.
130 mm x 130 mm.
The maximum length of twin wall flue pipe to be installed externally is?
1 metre.
2 metres.
3 metres.
4 metres.
The minimum clearance from the inner part of a twin wall chimney pipe to combustible material is?
15 mm.
25 mm.
50 mm.
100 mm.
A terminal is required on a chimney outlet when the diameter is equal to or less than?
100 mm.
125 mm.
150 mm.
170 mm
What is the minimum distance that a chimney outlet should terminate above the ridge on a pitched roof?
250 mm.
600 mm.
1 metre.
1.5 metres.
The annular space between a chimney and a flexible metal flue liner?
Does not need to be sealed.
Must be sealed at the top only.
Must be sealed at the bottom only.
Must be sealed at the top and bottom.
A gas fire and back boiler is to be installed into an existing brick built chimney, what maximum length would the chimney require to be if it was not lined?
No figure, any length of chimney needs to be lined.
6 metres.
10 metres.
12 metres.
The ‘catchment space’ (void) at the base of a brick built chimney which was previously used for an oil boiler and is now intended to serve a gas fire, must have a minimum volume of?
2 dm³
12 dm³
75 mm
250 mm
Passive stack ventilation systems may cause what problem with open flued, natural draught appliances?
Excessive ventilation.
Noisy burner operation.
Pilot outage.
Spillage of products of combustion.
Open Flued, Fanned Draught Chimney Systems
What period of draught failure would result in ‘burner lockout’?
1 second.
2 seconds.
6 seconds.
10 seconds.
Open Flued, Shared, Natural Draught Chimney Systems
Appliances utilising this chimney system must be?
Natural draught with a draught diverter.
Fanned draught with electronic flame supervision device.
Under 40 kW net combined heat input.
B11 have an ASD and an FSD.
Room Sealed, Natural Draught (Balanced Flue) Chimney Systems
The main safety advantage of this appliance type by comparison to type B appliances is that?
It can be used during a power cut.
It is more efficient.
It requires less maintenance.
The combustion process is sealed from the room.
A terminal guard is required when the flue terminal is less than?
1.5 m above ground level
1.8 m above ground level.
2 m above ground level.
2.1 m above ground level.
The specification of a terminal guard is?
50 mm clearance from terminal and the minor dimension of any opening less than 16 mm.
25 mm clearance from terminal and the minor dimension of any opening less than 16 mm.
50 mm clearance from terminal and the minor dimension of any opening less than 10 mm.
25 mm clearance from terminal and the minor dimension of any opening less than 10 mm.
Room Sealed, Fanned Draught (Balanced Flue) Chimney Systems
A terminal guard is required when the flue terminal is less than?
1.5 m above ground level
1.8 m above ground level.
2 m above ground level.
2.1 m above ground level.
A flue assembly passing through a combustible wall shall be within a non-combustible sleeve providing an air gap of?
5 mm.
10 mm.
15 mm.
25 mm.
Flue assemblies passing through ceiling voids?
Are not permitted.
Must be insulated.
Must be accessible for inspection.
Must be 100 mm from any power cables.
Balanced Compartments
A balanced compartment?
Must be vented on the wall at high and low level directly to outside air.
May be vented either to room or to outside.
The compartment structure is a functional part of the installation.
Must be constructed entirely of fire resistant material.
SE Ducts and U Ducts
On a SE duct chimney system appliances must be?
Open flued.
Fitted with an ASD.
Installed in basements.
Designed and approved by the manufacturer as suitable.
On a U duct chimney system the?
Inlet and outlet are above roof level.
Inlet and outlet are below roof level.
Inlet at high level and outlet at low level.
Outlet at high level and inlet on an internal wall.
Vertex Flue
A vertex chimney system provides?
A room sealed, fanned draught appliance utilising an open flue.
A room sealed, natural draught appliance utilising an open flue.
An open flue, fanned draught appliance.
An installation whereby the loft space becomes a balanced compartment.
Condensing Flues
Condensing flues?
Will always have any horizontal pipe falling towards the terminal.
Will always have a cast iron condensate discharge pipe.
May be made from plastic.
Must always terminate vertically
Room sealed chimney outlets
What is the minimum clearance required between a vertical down pipe and a room sealed, fanned draught combi boiler (maximum rated input 27 kW net) flue terminal?
75 mm.
150 mm
300 mm
Zero.
What is the minimum clearance required between a room sealed, natural draught wall mounted boiler ( maximum rated input 14 kWnet ) flue terminal located directly below an openable window?
300 mm.
600 mm.
1500 mm.
2000 mm.
Positive Pressure Case Appliances
Why is a positive pressure cased appliance potentially more dangerous than a negative pressure cased appliance?
If the appliance room seal is damaged CO² may be blown into the room.
If the appliance room seal is damaged CO may be produced and be blown into the room.
If the appliance room seal is damaged any gas escape inside the appliance will be blown into the room.
A through draft will be generated which could depressurise the room affecting the operation of open flued appliances.
How could you recognise a positive pressure cased appliance?
Loosen the case screws and test for positive or negative pressure with a smoke match with the appliance operating.
Age; all fanned flue boilers manufactured before April 1998 are positive pressure.
Check for inclusion on the list and/or examine the position of the fan in relation to the heat exchanger.
With the boiler in operation, apply a smoke pellet to the terminal and check for smoke escaping from the case seal into the room.
Communal Flue Systems
On a CFS (Shared or Communal Flue system) how can you identify if a concentric system is natural or fanned draught?
Remove the inspection plate at the base of the flue, if the inner duct is open it is natural draught, and if closed fanned draught.
Remove the inspection plate at the base of the flue, if the inner duct is closed it is natural draught, and if open fanned draught.
Apply a smoke pellet to the air inlet and see if it is drawn in or blown out.
Refer to the appliance manufacturer’s instructions to confirm what the flue type is.
Communal flue systems are designed to?
Replace all open flue appliance / chimney systems.
Replace all balanced natural draught flue / chimney systems.
Designed to take multiple appliances in a block of flats or high rise situation and can replace SE- ducts and U – ducts.
Designed to take multiple appliances in a block of flats or high rise situation and can replace SE- ducts and U – ducts, plus accommodate any condensate from an appliance.
The type of appliances suitable for fitment to shared flue systems are?
B11.
C12
A
C42
Fan assisted CFSs require a …………………. fitted in the exhaust gas flue to prevent POCs from entering the appliance when not in use.
A draught stabiliser.
A non return valve
A double check valve
A snorkel
Naturally ventilated or fan assisted exhaust only CFSs (CFS/EO) have a?
Inlet and outlet above roof level.
Inlet and outlet below roof level.
Common duct for the removal of POCs whether it is natural or fan assisted and terminates above roof level, with air supply ducted separately from outside the building.
Outlet at high level and inlet on an internal wall.
Testing Open flue, Natural draught Chimney Systems
When working on an appliance which has an open flue, natural draught, metal chimney, what flue checks must be carried out?
Visual only.
Flow and spillage.
Spillage only.
Visual, flow and spillage.
A flue flow test must be performed with the?
The doors and windows open.
Appliance operating and the doors and windows open.
Appliance off and the doors and windows closed
Appliance connected to the chimney.
If there is no draught present when the flue is cold?
The flow test is deemed to have failed.
Specialist advice is required.
The test must be performed when the wind is stronger.
The flue must be heated using a blow torch or by operating the appliance.
A test for spillage must be performed with?
The doors and windows open.
Appliance operating and the doors and windows open.
Appliance off and the doors and windows closed.
Any extraction fans in the same or adjoining rooms operating.
When performing a test for spillage the smoke must be applied?
Within 5 minutes of lighting the appliance.
More than 5 minutes after lighting the appliance.
Exactly 5 minutes after lighting the appliance.
After the appliance has heated up.
