thoule wrote: I thought of a new coal furnace, but fear it will hurt the resale of the house - future home buyers won't want to maintain a coal furnace (or is it called a coal boiler?).
Actually its selling point IMO. Firstly you'll be able to give them the amount you are paying which will probably make their jaw drop.
Secondly and I guess this depends on how much space you have but what many people here are doing is just leaving the oil boiler installed. They power vent the oil boiler and use the chimney for the coal. You'll have two furnaces, you use the oil for backup. You don't have to power vent it. Just leave it so you can easily disconnect the coal furnace and hook it up to the chimney in case of emergencies or you want go away in the winter for a week Others have also hooker them up in tandem and set them up so the oil furnace would only come on in case of the coal boiler failing.
A few companies actually have this setup for the coal boilers but they are apprently not very efficient with the oil, best used just a backup or when you need it.
Also remeber with a boiler you'll have a water coil for hot water use, the larger furnaces are meant to be run year round. It's about equal or even cheaper providing hot water in the summer so that is not an issue. Burning year round will also greatly extend the life of the furnace..
As far as the Keystoker 90 if you're going to put it a living space that is probably the size you'll want unless you can get the heat to circulate, anything else is going to roast you out of that room. the 90 could probably do that by itself. If you put it in the basement you could probably get enough heat to circulate upstairs with some minor modifications (e.g open the basement door and maybe one floor vent somewhere). There's a few topics in the venting/plumbing section on how to circulate it.