Thanks for the info.
Until the OP can provide more info (efficiencies, location, etc), we're all really just groping in the dark. It's interesting to see how different posters (with different viewpoints) respond to these types of general questions, though.
A. Where does the wood stove gets its combustion air from. Does it have an intake that is ran throught he wall. Or does it use air from the bedroom.
Originally Posted by equspainc
If air from the bedroom, then it is part of the problem.
B. What size is your furnace, and how long does it run on a 20 degree day.
A furnace fired at .75 gal an hour would need a burner run time of over 13 hours.
C. Your water heater runs to maintain water temp weather you used hot water or not.
Time your burner run times, if you want to find which one is using the most oil.
Also, is your tank buryed under ground. Is it possible it leaks.