An Experimental Thermal Analysis of Domestic Flues Serving Closed Solid Fuel Appliances

A set of pragmatic experimental investigations were initially undertaken using three straight flues attached to glass doored solid fuel appliances. Each system was built to satisfy existing regulatory requirements and instrumented with type K thermocouples at fixed locations within each flue. The fire gas temperatures were analysed for periods of steady state operation. It was concluded that existing theory gave a good prediction of flue gas temperatures in straight flue at low and slumbering burn rates. Also, preliminary investigations on a flue modified to include a bend within its vertical height indicate that the thermal analysis used to describe the excess gas temperature variation with height in the straight flue could also be used to predict gas temperatures in flues containing a bend. An error analysis shows that an experimental error of less than 10% can be assumed for the flue gas temperatures based on the use of a theoretical expression that links excess flue gas temperature to height within the flue system.