Boilers use Water while Furnaces use Air to Heat Homes.
When the cold air hits and the familiar sound of the heating system isn't heard, it's time to have your heating system looked at and possibly replaced. A common issue that comes about is what kind of heating system do I have, a boiler or a furnaces and what is the difference?
Well there is a big difference between the two, first is the efficiency and how the each equipment heats the home. Boilers use water or steam, while furnaces use air to heat the home. This is where the terms forced hot air or forced hot water come from, as the system will force heated water through base boards or radiators or heated air through duct work.
Boilers traditionally are more energy efficient than furnaces due to the delivery of the heated source. There is a lower amount of energy loss from piping involved with a boiler than the duct work that is required for a furnace. The energy energy rating for your heating system is represented as an annual fuel utilization efficiency or AFUE. The AFUE for most boilers is actually lower than furnaces, this is because the AFUE rating doesn't take in consideration heat loss through the duct work. Heat loss from the duct work in your home can account for 30% your heating use.
However furnaces allow for an easier installation of a central air condition system, much much easier. Central air conditioners require duct work to deliver the cool air. This is almost impossible with a boiler without expensive duct work that would just be used during hot months here in the Northeast.
The easiest way to tell the difference is go into your basement, go to your heating system, if the system is tall and rectangular in shape you have a furnace. The top of furnace should connect to duct work that will distribute the heated air through the home. This should not be confused with a chimney, as boilers and furnaces need to vent in air to keep their flames going.