CCN1 Flue Systems and Chimneys

Question 1

What is the minimum vertical distance a room-sealed balanced flue terminal must be from ground level or a surface people can stand on?

Accepted Answer

300 mm

Answer

150 mm

Answer

600 mm

Answer

1000 mm

Question 2

What type of flue system draws combustion air from the room and discharges products of combustion to the outside?

Accepted Answer

Open flue (Type B)

Answer

Room-sealed flue (Type C)

Answer

Flueless (Type A)

Answer

Forced draught flue (Type D)

Question 3

What is the purpose of a draught diverter (draught break) fitted to an open-flued gas appliance?

Accepted Answer

To prevent excessive draught (down-draught or up-draught) affecting the burner and to allow dilution air to enter the flue

Answer

To increase the flue draught to maximum

Answer

To filter particles from the combustion products

Answer

To regulate the gas pressure to the burner

Question 4

When carrying out a flue flow test (spillage test) on an open-flued appliance, where should the smoke match be held?

Accepted Answer

At the base of the draught diverter or canopy

Answer

At the flue terminal on the outside of the building

Answer

At the gas meter

Answer

At the ventilation grille

Question 5

What is the minimum internal diameter of a flue liner suitable for a standard domestic gas boiler?

Accepted Answer

125 mm

Answer

75 mm

Answer

100 mm

Answer

150 mm

Question 6

A fanned draught flue system operates by using what method to discharge combustion products?

Accepted Answer

An electrically powered fan to push or pull combustion products through the flue

Answer

Natural convection (buoyancy of hot gases)

Answer

Compressed air injection

Answer

A venturi effect created by wind passing over the terminal