I currently have a 1960's Lennox Oil Furnace. I am looking to replace it, and was going to go with Natural Gas, but found out, they were not able to get a line up to my house, so that option is out. I talked to my local plumbing/heating company, and they told me about an air source heat pump. After talking to him, i talked to some other people, and also did some research online, and some people have told me that air source heat pumps are not a good idea in Minnesota, where the winter temperatures are very cold. The plumbing/heating company told me that their heat pumps that they install will work down to 15 degrees...then they install a plenum heater or resistance heater, cant remember what he said, and that will kick in and help the heat pump when temps get below 15. Temps here in Minnesota sometimes never get above 0 degrees in the winter for several days...Is this still a good idea? Please help, as winter is coming and I need to get something done here in the next month or so.