it's an unknown thus far....as it's my first year here..
to answer tho , i will always say....   
as least as possible...
next winter i plan to have stacks of wood everywhere 
enough for 
two winters...
and keep the oil burning mainly to heat hot water...
the whole back of the house is perfect for solar heating systems
and that will be my heating weapon of choice in the future.
it's 5 am and 2 about degrees outside 
and i'm headed out to the barn to scrounge up a box of wood .
