Masonry chimneys have been a major appliance venting system for decades. technological advancement and efficiency increase in gas appliances result in less heat and lower temperature vent gases being vented. The flow and thermal environment in the chimney are altered, leading to a potentially unfavourable situation for successful flue gas venting. By following the new venting guidelines, masonry chimneys can be safely used to vent flue gases from a fan-assisted combustion system (FACS) mid-efficiency, Category I, gas-fired appliances. Identifies procedures - inspecting and relining - diagnoses and resolves masonry chimney venting problems.

KEYWORDS: masonry, chimneys, gas, appliances, gas installations, combustion gases, flue gases, vents, inspecting, fans, safety.