I've got an 11 year old furnace, which is supposed to be an auxillary for a heat pump. The former owner took the heat pump with them, so I'd like to install a new one. Turns out that the furnace (which is working properly) is just old enough to not be compatible with heat pumps currently on the market. The choice is either to replace the furnace with one that works with current heat pumps and get a new heat pump, or track down an older model heat pump that is compatible...either a hard-to-find new one, or a used one that probably won't be guaranteed by the manufacturer. The technician explained all this and asked me questions to help me determine which option would be best for my situation. Still not sure what I'm going to do, but I appreciated getting all the information.