What I think most of us coal burners need is an outside air supply to satisfy our constant combustion cycle. Why take warm air to supply air to your stove. Some have plumbed outside air to their stoves, this does 2 things. First it makes it so the stove doesn't have to draw from any leaks in the house if you have them, and second why take heated air for combustion? ""The Air to Air exchangers you where looking at are to refresh stale air in a house, such as a house with extremely tight insulation, they do not supply more air than they expell.to the outside.