A gas burner unit for a cooktop includes a spreader having a first side with a plurality of gas outlets and a second side opposite the first side and defining a portion of a fluid path. The spreader further defines a venturi in fluid communication with the gas outlets and extending away from the second side. The gas burner unit further includes an orifice holder having a protrusion defining an upwardly directed primary air inlet therethrough. The upwardly directed primary air inlet is in fluid communication with the fluid path associated with the spreader on a first end thereof and with the venturi on a second end thereof opposite the first end.