Spačva is a Croatian manufacturer of parquet and joinery made from Slavonian oak. They produce excellent pellets from the production residues. This means that the pellets do not contain bark and other parts of the plant, which does not contribute to higher heating power, but causes more ash.
Oak pellets are slightly softer than spruce pellets and are therefore recommended in some boilers where harder pellets can cause the auger to block the pellets loading the firebox.
