Wood burner covers a massive list of fires, these are all designed to have a very cool flue
the first two are condensing, and the latter also burns super efficiently, but other than the rocket centre which is a DIY type the other two need electric to run, and my question which was not answered was what happens with a power cut?
I know my mothers house with the old aga stove had a quarry tiled floor so one could rake out the fire safely and carry the burning coals outside with nothing likely to catch fire.
My dad looked after multi fuel boilers, it could run on blast furnace gas, town gas, oil, or solid fuel, however it never used solid fuel all the time he looked after it, but it was also rather inefficient, it was used as it basic burnt waste produces, when the coke ovens closed so did the power station, but to burn multi fuels the burner needs adjusting for each fuel, most woods and coal have around the same calorific value per unit weight, but the burner is restricted by volume not weight, so the volume needs adjusting to match the fuel.
Burning coke or charcoal is OK as all nastiness removed, but wood and coal need very careful temperature control to reduce emissions, too hot and waste heat, too cold and nasty stuff in flue gases, this means they have to burn at a set rate, so the normal is to have water heating so energy can be stored and released as required, these systems
seem to be the bees knees, and my brother-in-law had one which did work very well, installed as the house was built, so no problem having a reinforced floor for the twin massive water tanks, however when he moved, and looked at fitting one in new house, well rather an old house, the cost of install was simply silly, with quotes in excess of £10,000 to install.
I have an open hearth fire, there for emergencies, board in front of the fire with pipe to AC so only hot air goes up the chimney normally, I have solar panels, and a battery with built in UPS so central heating will still run with no grid power, so unlikely I will ever used the open grate, have not fitted a modern efficient fire as then could not use chimney for the AC. Also I am old enough to remember coal fires, and all the dust due to them, drafts in the house, and carrying out ashes, no thank you, I still light coal fires, but not at home. I work on the local heritage railway and Polish coal is not a patch on Welsh coal, getting coal is becoming a real problem.