We installed a high efficiency propane furnace in a 2400 sf house heated by a wood stove and passive solar. The propane company took care of delivering and installing a tank (leased), regulator and took the line to where the furnace was installed by a heating company. I did the duct work off their plenum and the whole thing was surprisingly reasonable.
I would never have gotten the $375,000 for that house when we sold it last year without that central heat system! Do it as soon as possible and enjoy the benefits yourself. It is worth every nickel.