A combustion air blower includes a blower housing, an impeller fan within the blower housing, and an embossment to restrict airflow from the combustion air blower. The blower housing has a discharge conduit defining a discharge passageway. The discharge conduit is adapted and configured to receive a baffle such that, when the baffle is received, the baffle extends inwardly into the discharge passageway from a first wall towards a second wall opposite the first wall. The baffle restricts airflow within the discharge passageway. The embossment is in the discharge passageway and in the second wall and extends towards the first wall such that the embossment restricts airflow within the discharge passageway. The embossment cooperates with a baffle to provide a reduced cross sectional area of the discharge passageway in comparison to an upstream portion.