I currently have a very old oil furnace. Its a Lennox, probably installed in the mid 1950's. Still heats very well, but the problem I have is with the blower fan motor. It doesnt run fast enough and so it doesnt blow much air out of the ducts. I have tried speeding it up, but its going as fast as it will go. Question is if I get a heat pump and use my old oil burning furnace as a backup, will the heat pump run off the furnace? Therefor my new heat pump will not be working as well as it should be. Or would I be better off getting a heat pump and a new natural gas furnace? Only problem there is we are talking about $12,000 for both the heat pump and the new gas furnace. By the way, I live in Minnesota, so the winters get very cold, so I definately need a backup heat source. Thanks in advance!