Not to mention the need for the 5" Flue in place of the 3" one. If you really want to save money, get a Geothermal heat pump to replace the old A/C and heating unit and use the heat transfer off of it to fill the tank with ample hot water. Run Pex water lines under the flooring to produce radiant heat and install solar panels and a wind generator to operate the new Geothermal heat pump you just installed.
Oh, and add me to your will if you can afford all that stuff.