Instead of a metallic reheating surface, there is a top-mount boiler integrated fin-type heat exchanger on the fireplace. The fin-type structure significantly increases the heat exchanger surface, allowing more compact and lower top-mounted boilers. This allows for more compact and lower boiler tops. Deposits on the fin-type surfaces are burnt off due to the high temperatures on their surface.
Consult your stove builder to find the right heating insert for your home.