We've now had about 7 contractors come to our house and give us estimates for replacing a) our oil heater (system from the early 1980's, estimated at around 65% effeciency), and b) our central air unit (system from the late 1980's, but no heat pump). There is no option for gas here.
The contractor we liked the most offered a price of around 7800 for the new furnace at 87.2% effeciency. However our current oil company offered us a price of about 4800 for a new furnace at 86.1% effeciency.
With the heat pump the oil should only really kick on 3-4 months out of the year (we live in PA, and based on temperature averages for the past 50 years that's what it comes out to, assuming the pump keeps us warm in our 1100 sqfoot house to about 30 degrees). So, assuming a 30 year lifespan of the heater, do you think the extra 1.1% effeciency would pay for the 3000$ difference between the two contractors? Which system would you choose?
I have no idea how to approach the math on this one.