Masonry Heaters Also known as masonry stoves, kachelofens, Russian fireplaces, Finnish fireplaces, Swedish stoves, tile stoves, contra-flow fireplaces, radiant fireplaces and mass-storage fireplaces. Inside, masonry stoves burn hotter than metal wood stoves and their winding maze of flue (baffles) warms the surrounding masonry, which then emits heat for 18 to 24 hours.