I am not sure which way to vent the coal furnace I'm getting. I can use the chimney the oil burner used, but it has a stainless liner in it. The other option for now is to power vent the coal furnace.I will some day have a new chimney installed,but need to get things running this year!
I'm not an HVAC expert but here's my suggestion: You don't want to power vent a coal furnace as it would need to run 24/7. If you aren't going to use your oil burner, disconnect it & use it's chimney. If you are still going to use the oil burner occasionally, power vent it. (the oil burner) Others may have different suggestions.
I would power vent the oil burner as you will hardly be using it and use the chimney for the coal furnace. Like devil said, the power vent will need to run 24/7 with the coal furnace using more electric and just more of a chance for something to go wrong with the power vent.