If the new unit you are talking about is the one from JJE elecctronics, it is indeed forced draft ( from a fan) but is certainly not boiling. It is completley cold water vapour. It works, Jim tells us, by a unit which creates tiny water droplets which are then blown up the funnel or whatever by a small fan. Good points are that as there is no heat involved, then 1, it is instant (no heating up). 2, it can be piped from the unit to it's exit point ( funnels, exhaust pipes) in palstic tubing as there are no heat concerns, and 3, because it's water mist, you can add food dye directly to the water and get asny colour "steam" that you want. try adding some rdark blue and look what good diesel smoke you get !
Aston