Abstract: A rotary thermal wheel assembly for heat transfer, mass transfer or a combination of heat and mass transfer has a hub, a number of rigid spokes which are connectable to the hub, and a heat and/or mass transferring media pack. The media pack is arranged in the space defined by the hub and the spokes. The hub is a tubular element provided with connection means, and the spokes are connectable to the hub by connection parts which match the correspondingly shaped connection means of the hub.