Hello.
I have a thought.
I have a central chimney stack in a 1960s house. There was an oil boiler until the early 90s. Subsequently an electric boiler followed by an air-to-water pump.
Anyway, the chimney stack has a central chimney flue that's not so tricky to get approved, but fitting a wood boiler is a bit more complicated. The existing boiler (CTC EcoEl 1550 + an air-to-water pump) is located quite close to the stack. It could be moved perhaps 40-50 cm away, albeit at some plumbing cost...
There are, for example, water-jacketed inserts that can be placed in an open fireplace. Is it theoretically possible to hack open the chimney stack and install a smaller fireplace there? The chimney stack has 5 flues, 4 for ventilation and one chimney in the center.
3 of the ventilation flues have their room connections at the top of the ground floor rooms (bathroom/laundry/boiler room) and the fourth is on the upper floor.
Theoretically, this means that only the chimney flue is in the last 150 cm of the lower part of the chimney stack.
It should still be load-bearing, right? Can it be supported? Hollowed out?