I hate mouldy smells with a vengeance! This is totally unscientific but my experience of getting rid of them is lighting a fire and opening the window for a few days. I once got rid of dry rot doing that. Which you can't do as the chimney breasts have gone. You could install a multifuel burning stove (they run the flue pipe up through the rooms/loft out onto the roof). I don't know much about the ventilation systems but imagine that could help.
To create mould you need warmth, damp and a lack of air/ventilation. Central heating can be not hot enough to kill it. A fire can be - and it also recirculates the air by drawing it up the chimney. I'd have thought it was unlikely to be coming from the tiles, unless they are laid on a wood floor which has rotted underneath. Sorry that isn't much help. We once had a powerfully mouldy smell in a living room with a carpeted timber floor - it always got worse when the heating was on and caused me asthma problems. In hindsight, if we had lit a fire in that room regularly that could well have solved it.
It's really hard finding a balance of insulation and ventilation these days - my thougts on it are - keep draughts out, but keep it ventilated.
To create mould you need warmth, damp and a lack of air/ventilation. Central heating can be not hot enough to kill it. A fire can be - and it also recirculates the air by drawing it up the chimney. I'd have thought it was unlikely to be coming from the tiles, unless they are laid on a wood floor which has rotted underneath. Sorry that isn't much help. We once had a powerfully mouldy smell in a living room with a carpeted timber floor - it always got worse when the heating was on and caused me asthma problems. In hindsight, if we had lit a fire in that room regularly that could well have solved it.
It's really hard finding a balance of insulation and ventilation these days - my thougts on it are - keep draughts out, but keep it ventilated.