As with most 20 year old houses, things start to need to be replaced.  We already replaced the carpet, sanded the hardwood floors and refinished them, reroofed and repainted the house.  All that's left to do were the furnace and hot water heater. The furnace died in the early winter, so we replaced it with a new high efficiency one.  The hot water heater is still hanging on ... Since we were replacing the furnace and adding an air conditioning unit was just a bit more, we decided to go for the whole shebang!