Our little taverna in Lafki has an ingeniouse arrangement to heat water for the radiators. In the open hearth the grate holding the fire embers is made of copper tubes, which are shaped like the letter C, with the open end facing outwards. At the top and front, in other words the ends of the CCCs, are brazed larger tubes to form manifolds. There are pipes connected to the manifolds to act as flow and return connnections to the radiators, the whole system is filled in the normal manner useing a filling loop and expansion vessel. Circulation is by a pump. Although there are no controls it would be a simple matter to include them.
The woodburning stove in our house has included in it, a heat-exchanger that can provide hot water for any purpose, but I have'nt bothered to connect it up as yet.