Abstract: A heat exchange unit for delivery of moulding sand in foundries. The sand is heated or cooled, as desired, by contact in its fluidized state with a heat exchange surface. The delivery temperature may be thermostatically controlled. The unit is capable of intermittent delivery, fluidization ceasing when delivery ceases so that the sand in direct contact with the heat exchange surface insulates the bulk of the sand therefrom. Delivery temperature on recommencement is therefore substantially the same as before cessation. By-pass means may be provided to ensure delivery of sand in the event of malfunction of the unit or during maintenance.