A burner comprising a first, upstream front wall, second downstream front wall, a general airflow direction being from the first, upstream front wall to the second, downstream front wall, wherein at least one partition wall (21, 22, 23, 25, 26) extends across the general airflow direction and between the first and second front walls, whereby the at least one partition wall divides a space between the first front wall and the second front wall into at least two separate fluid plenums (31, 32, 33, 35, 36, 37, 38) stacked along the general airflow direction, the burner further comprising at least one peripheral wall (28, 29) extending between at least one of: the front walls, at least two partition walls, and/or a front wall and at least one partition wall, wherein a multitude of passages (40, 40a, 40b, 40c) are provided through the first and second front walls and the at least one partition wall, wherein a multitude of ducts (41, 41a, 41b, 42, 43, 44a, 44b, 44c, 45, 46, 47, 48, 49, 141, 142) are provided, the ducts extending through at least some of the passages and the ducts extending through the fluid plenums wherein the duct walls are leak-proof connected to the first front wall, the second front wall and the at least one partition wall, so as to provide fluid communication between an upstream side of the burner adjacent the first front wall and a downstream side of the burner adjacent the second front wall, and wherein each duct has a first, upstream end adjacent the first, upstream front wall and a second, downstream end adjacent the second, downstream front wall, wherein the burner comprises discharge means (51, 52, 53, 56, 57, 58, 61, 61a, 61b, 61c, 62, 65, 152, 162) for providing fluid communication between at least one of the fluid plenums and the interior of at least one duct out of the multitude of ducts and each discharge means being configured for discharging a fluid from a fluid plenum into a duct out of the multitude of ducts, wherein at least one of the discharge means is a wall-opening type discharge means (51, 52, 52a, 52b, 53, 56, 57, 58, 152) which is provided as at least one through hole through a duct wall and wherein at least one of the discharge means is a nozzle type discharge means (61, 61a, 61b, 61c, 62, 65, 162) which is provided as a discharge nozzle which is suspended in a duct by a tube extending from a fluid plenum to the discharge nozzle and providing fluid communication between said fluid plenum and the discharge nozzle, wherein at least one duct (43, 44a, 44b, 44c, 45, 47, 48, 49, 141) out of the multitude of ducts is provided with at least two discharge means, wherein said at least two discharge means are provided to discharge a fluid from inside the respective fluid plenum at different positions along a longitudinal direction of the duct. whereby the at least one partition wall divides a space between the first front wall and the second front wall into at least two separate fluid plenums (31, 32, 33, 35, 36, 37, 38) stacked along the general airflow direction, the burner further comprising at least one peripheral wall (28, 29) extending between at least one of: the front walls, at least two partition walls, and/or a front wall and at least one partition wall, wherein a multitude of passages (40, 40a, 40b, 40c) are provided through the first and second front walls and the at least one partition wall, wherein a multitude of ducts (41, 41a, 41b, 42, 43, 44a, 44b, 44c, 45, 46, 47, 48, 49, 141, 142) are provided, the ducts extending through at least some of the passages and the ducts extending through the fluid plenums wherein the duct walls are leak-proof connected to the first front wall, the second front wall and the at least one partition wall, so as to provide fluid communication between an upstream side of the burner adjacent the first front wall and a downstream side of the burner adjacent the second front wall, and wherein each duct has a first, upstream end adjacent the first, upstream front wall and a second, downstream end adjacent the second, downstream front wall, wherein the burner comprises discharge means (51, 52, 53, 56, 57, 58, 61, 61a, 61b, 61c, 62, 65, 152, 162) for providing fluid communication between at least one of the fluid plenums and the interior of at least one duct out of the multitude of ducts and each discharge means being configured for discharging a fluid from a fluid plenum into a duct out of the multitude of ducts, wherein at least one of the discharge means is a wall-opening type discharge means (51, 52, 52a, 52b, 53, 56, 57, 58, 152) which is provided as at least one through hole through a duct wall and wherein at least one of the discharge means is a nozzle type discharge means (61, 61a, 61b, 61c, 62, 65, 162) which is provided as a discharge nozzle which is suspended in a duct by a tube extending from a fluid plenum to the discharge nozzle and providing fluid communication between said fluid plenum and the discharge nozzle, wherein at least one duct (43, 44a, 44b, 44c, 45, 47, 48, 49, 141) out of the multitude of ducts is provided with at least two discharge means, wherein said at least two discharge means are provided to discharge a fluid from inside the respective fluid plenum at different positions along a longitudinal direction of the duct.