Wood stove combustion air retrofits: A low cost way to increase energy savings in dwellings

In Europe, wood-fired stoves remain as major renewable household heating and emission sources. This study focused on improving the performance of a wood stove (natural draft) traditionally used in Portugal by the adoption of alternative combustion air retrofits. Additionally, the performance of a new pellet stove (forced-air) was determined to investigate the highest achievable goal for solid-fuel stoves. In the wood stove, an outer chimney component was installed around the existing chimney to allow the vertical admission of outdoor air that was preheated before entering the combustion chamber. This measure increased the thermal efficiency of the wood stove from 62% to up to 79%. Another component was used to administrate secondary air to the wood stove reducing the carbon monoxide emissions by 39% to 2808 mg Nm−3. The two retrofits enhanced a more stable heat release from the wood stove, which reached a thermal efficiency 11% lower than that achieved by the pellet stove. This research suggests that retrofitting stoves with chimney components that allow the admission of combustion air can substantially increase energy savings in dwellings. Further efforts should focus on improving the interplay between the outdoor air and secondary air admission to achieve higher emission reductions at low-cost.