Flue Requirements & Pressure Relief Flashcards

What is the required minimum distance between a flue terminal and the ground level in a publicly accessible location?

Answer: 2100 mm (2.1 m)

Where a flue terminal is at low level in a publicly accessible area, it must be at least 2100 mm above the ground or guarded with a terminal guard to prevent burns or blockage.

What is a terminal guard and when must it be fitted?

Answer: A mesh guard fitted over a flue terminal when it is at low level or where it could be touched or blocked

A terminal guard is required when a flue terminal could be touched, blocked or damaged — typically at low level or in areas accessible to the public; it must not restrict flue gas flow.

What is a 'Type C' gas appliance classification?

Answer: A room-sealed appliance with both air supply and flue gas ducts connected to the outside

Under European classification, Type C (or category C) appliances are room-sealed with both combustion air and flue gas ducts connected directly to the outside atmosphere.

What is the minimum free area of permanent ventilation required for an open-flued gas appliance of 10 kW input rating?

Answer: As specified in BS 5440-2, typically 5 cm² per kW for a rated input above 7 kW (so approximately 15 cm² plus 5 cm² per kW above 7 kW)

BS 5440-2 specifies ventilation requirements for open-flued appliances; the formula gives the minimum permanent vent area based on the appliance heat input to ensure adequate combustion air.

What action should a Gas Safe engineer take if they find a CO alarm sounding at a property?

Answer: Evacuate the property, call the gas emergency number, ventilate, investigate for source of CO before re-occupying

A sounding CO alarm must be treated as a genuine emergency: evacuate all occupants, ventilate the property, call the gas emergency number (0800 111 999), and do not re-enter until cleared by a competent engineer.

What standard specifies requirements for the installation of gas flues in domestic buildings?

Answer: BS 5440-1

BS 5440-1 covers flues and ventilation for gas appliances of rated input not exceeding 70 kW in domestic buildings, specifying design and installation requirements for flue systems.