Ovale T 5kw Curved - Defra Approved Contemporary Wood Burning Stove. Ovale T 5kw. Defra Approved Curved Wood Burning Stove With Optional Direct Air. Eco Design Compliant & Defra Certified. The firebox is fully lined with heat proof vermiculite to prolong the life of the appliance and to reflect the heat out from the firebox into the room.