I think you're missing the point. This is not an argument about the merits of wet & dry heating systems. I agree the new systems with heat recovery and fresh air systems are much improved. But the OP was asking about an existing system in a property they are considering living in and I think the possibilities of it being a twin duct forced air heat recovery and ventilation system are very slim.When the house is designed for it they are not expensive to install. As I said "Give me a twin duct forced air heat recovery and ventilation system any day. Beats the hell out of radiators."