If you are like most homeowners, the furnace hasn't exactly been a priority since you switched the thermostat to 'cool' last summer. That could soon change, however, especially if you own an older furnace. By today's standards, your furnace is a candidate for replacement if it's 15 years or older. Although your older furnace may still be running and providing sufficient heat, it's less energy- efficient than currently available equipment, which means your fuel bills are higher than they need to be. For an exact measure, a heating contractor can test your furnace's efficiency.
Many utilities offer rebates to encourage consumers to buy higher-efficiency furnaces.
This is the key to making an intelligent financial decision about whether or not to replace your existing furnace. You'll see how long it takes for the furnace to pay for itself. There is no magic formula for deciding what fuel is best except by determining what types of fuel are available locally and their current prices. Electricity is the cleanest yet most expensive. Local fuel prices can fluctuate from year to year.