I recently removed my old combi boiler in favor of a geothermal heat pump in the basement, and now I'm left with a hole in the chimney where the flue pipe used to connect. I'm thinking of installing some kind of disc vent or similar instead (I got the idea that it might be good for a bit of air circulation, etc.) But how do I do it, and is there any special vent designed for in-wall installation?
Feel free to give me tips on materials and execution. I'm not that skilled at masonry/plastering.
It doesn't need to be a super finish as the rest of the room isn't really a living room anyway.