Osby Wirbex-S is an over-pressure oil/gas boiler with a reverse-firing flame chamber and a centrally positioned burner. The convection section consists of tubes / turbolators that ensure excellent gas rotation and hence high heat transfer.

The adjustable front door has several layers of insulation and can be hung on the right or left.

The water connections are located as standard on the top of the boiler and have weld-on couplings. The boiler has a flue outlet at the rear. Ash removal is carried out from the front, through the front door, and there are cleaning ports on the side of the boiler at the rear.

The boiler is well insulated with mineral wool for good efficiency and covered with an enamelled sheet metal housing.