how much does your furnace use per year? how cold does it get (and for how long), how big is the house and is it well insulated?
I'm trying to figure out if it's really worth it to replace a furnace (after following the "should I replace a 9 y/o furnace" thread). We live in a 50 year old duplex (900 sq ft floor times 2 floors, plus basement and garage) where the walls aren't well insulated and the windows were bad (we changed the windows but I can't say if we'll use less fuel yet, winter's just beginning). It gets really cold in winter (-20, -30 celsius is common) for a long period of time. the furnace is an old iron tank and it's feeding about 18 baseboard heaters around the house.
the hot water tank (common to the whole house, so serving 2 families) is also running on the same oil as the furnace (from same fuel tank)
for the whole year we go through maybe 8000 liters of oil.