Air manifolds are used in straw-fired batch boilers to provide appropriate excess air as well as homogeneous air distribution in the primary and secondary combustion chambers. The paper presents the results of variant analysis of operation of the air manifold responsible for providing air for the combustion process in a biomass-fired batch boiler. An experimental stand consisting of a set of velocity sensors has been constructed to analyse the operation of the air manifold. The results of the experimental studies were implemented in a computational fluid dynamics model, which allowed to determine the elements of the manifold construction which are crucial from the point of view of the efficient combustion and acceptable low level of the fan's energy consumption. As a next stage of the studies, a new design of the manifold has been developed and modelled. The results of the studies and the recommendations for designing air manifolds have been presented. (C) 2018 Elsevier Ltd. All rights reserved.