Plant for the combustion of combustible, carbon-containing, optionally biological materials and for the recovery of the thermal energy thereby generated from the combustion gases having a combustion oven to be supplied with the mentioned materials with a supply of combustion air and having a guiding device, attached to said combustion oven, for guiding the hot combustion gases into and through a heat or warmth recovery device, - which is formed having a pipe heat exchanger which has a pipe bundle body divided, in particular lengthwise, by a pipe bundle partition wall into two pipe pullers (61, 62) having first and second pipe puller (61, 62) able to be flowed through one after the other by the hot combustion gases flowing directly out of the combustion oven, and a flue pipe connecting space, connecting directly to the pipe bundle body and connecting the two pipe pullers (61, 62) with one another, having connecting space partition wall partitioning the same, and a pipe evaporator disposed in the same, preferably connected with a turbine, with electricity generator, disposed externally to the pipe heat exchanger, - wherein the heat and warmth recovery device furthermore has a second pipe puller bypass pipeline leading off from the flue pipe connecting space and opening into a flue gas discharge space, connected on the output side only to the second pipe puller of the pipe heat exchanger, having exhaust gas discharge opening, having an openable or closable bypass locking flap, installed in its pipe branch leading off from the pipe flue connecting space, and - wherein at the connecting space partition wall in the flue pipe connecting space on the heat exchanger side is articulated a two-way locking flap which can be swivelled - either into a connecting position, towards the pipe bundle partition wall of the pipe heat exchanger, which closes in a substantially gas tight manner the combustion gas direct guiding opening there and which thus guarantees the guiding of the combustion gases - out of the first pipe puller through the entire flue pipe connecting space and in any case via the pipe evaporator disposed in the same into the second pipe puller or into the bypass pipeline - or into a closed position preventing the guiding of the combustion gases from the first pipe puller through the entire pipe flue connecting space and via the pipe evaporator located there, and thus guaranteeing their guidance immediately through the opened combustion gas direct guiding opening directly into and through the bypass pipeline or into and through the second pipe puller. - which is formed having a pipe heat exchanger which has a pipe bundle body divided, in particular lengthwise, by a pipe bundle partition wall into two pipe pullers (61, 62) having first and second pipe puller (61, 62) able to be flowed through one after the other by the hot combustion gases flowing directly out of the combustion oven, and a flue pipe connecting space, connecting directly to the pipe bundle body and connecting the two pipe pullers (61, 62) with one another, having connecting space partition wall partitioning the same, and a pipe evaporator disposed in the same, preferably connected with a turbine, with electricity generator, disposed externally to the pipe heat exchanger, - wherein the heat and warmth recovery device furthermore has a second pipe puller bypass pipeline leading off from the flue pipe connecting space and opening into a flue gas discharge space, connected on the output side only to the second pipe puller of the pipe heat exchanger, having exhaust gas discharge opening, having an openable or closable bypass locking flap, installed in its pipe branch leading off from the pipe flue connecting space, and - wherein at the connecting space partition wall in the flue pipe connecting space on the heat exchanger side is articulated a two-way locking flap which can be swivelled - either into a connecting position, towards the pipe bundle partition wall of the pipe heat exchanger, which closes in a substantially gas tight manner the combustion gas direct guiding opening there and which thus guarantees the guiding of the combustion gases - out of the first pipe puller through the entire flue pipe connecting space and in any case via the pipe evaporator disposed in the same into the second pipe puller or into the bypass pipeline - or into a closed position preventing the guiding of the combustion gases from the first pipe puller through the entire pipe flue connecting space and via the pipe evaporator located there, and thus guaranteeing their guidance immediately through the opened combustion gas direct guiding opening directly into and through the bypass pipeline or into and through the second pipe puller.