In an existing home, it's important to consider the impacts of replacing your current heating system with a different type of heating system. The easiest route is simply to replace your furnace or boiler with an updated model of the same type, but this may keep you from your most efficient heating and cooling options. Here's what you need to consider in the following situations:

• Switching Electric Resistance or Steam Heating to Hot Water Heating
• Switching Among Ducted Heating and Cooling Systems
• Adding Ducts to Your Home
• Switching Electric Resistance or Steam Heating to Hot Water Heating

Electric resistance heating, also called electric baseboard heating, is the cheapest to install and the most expensive to operate, as it is the least efficient source of heat. Unfortunately, upgrading to ducted systems, as discussed in the following section, will involve a significant expense for ducting. Another option is to switch to a hot water baseboard system. Baseboard heaters can probably replace electric resistance baseboards in the same location, but will still require extensive plumbing.

Steam systems are generally less efficient than hot water heating systems, but the efficiency gain of upgrading to hot water is probably not worth the expense; it would be better instead to upgrade or replace your boiler. However, it is sometimes possible to convert existing steam distribution pipes to hot water heating, which reduces the cost of the system to the cost of the boiler, the baseboard heaters, and the installation labor. This is generally only feasible in newer two-pipe steam systems (that is, systems in which two pipes go to each radiator, one for the steam and one for the condensate return). For some homeowners, the aesthetic and space-saving benefits of eliminating the large steam radiators may be worth the expense.