Firewood plays an important role in the transition towards more environment-friendly heating. How -ever, most installed wood stoves are outdated and demonstrate low efficiency and high emissions. New regulations force users to upgrade or replace their units. Diverse retrofit devices have been developed and tested, but none satisfy the required performance indicators alone and there is a lack of research on their combined operation. We studied the single and combined performance of three technologies (catalytic oxidation, heat recovery and ESP) using a fractional factorial experimental design. The experimental units were two single-room wood stoves equipped with an exhaust fan. The exhaust fan operation pulled down the efficiency by 7-10%. The ESP dropped the PM by 40-46% and reduced the efficiency by 2-3%. The heat exchanger fan increased PM emissions by 38-57%, while efficiency improved by 19-36%. The catalyst reduced the PM by 9-38% while the CO decreased by 31-56%. The combination of the exhaust and heat exchanger fans decreased the PM about 18% and increased the efficiency 26%, while the combination of the ESP and catalyst accomplished a 67% PM reduction. (c) 2021 Elsevier Ltd. All rights reserved.