The Difference Between A Furnace And A Boiler

The difference between a furnace and a boiler:

This is a question I have to sort out on many emergency calls that come into the office. 

These are the questions I have to return back to a customer in order to give them an answer:

• While the heat is running does air come out of floor or ceiling grills?
  
• Does Air blow around the house in normal use?
• Do you have air conditioning? If yes, does it come out of these same registers?
• Is there a sheet metal ducted system in the basement?

If you answer yes to all or most of these above questions you most likely have a Furnace.

If you answer no then:

• Does your heat come from baseboard type heating along the base of the walls?
• Does your home have cast iron radiators?
• Does the heating unit would have several types of piping and fittings attached to it, like copper and steel.

All these above question would be an indication that the heating unit is a Boiler.

Now there are a couple types of  boilers, Steam and Hot Water but none the less both are boilers.

Furnaces and boilers can be purchased so as to run on different fuels, the most common would be Natural gas and Oil though LP Gas has become a popular replacement to Oil.

In some cases there is a third unit called an Air Handler. This is a ducted system that also blows air.

In rural areas of the country Oil is still popular but Oil has limitations.
One of which, is it cannot be installed in upper levels of the home.
Larger type homes many use two or more ducted systems that are located in upper and lower levels including the attic.
For these type homes an Oil Boiler could be used in the basement or lower level.
Piping would be directed to an attic air handler providing 180 degree water to a car like radiator attached to the blower box.
As the air passes over the coil it is sent through the ducting to the desired areas for heating. The beauty of this system is that the ducting is used for both AC and heating.

In some cases an Air Handler may be used exclusively for Air Conditioning.
Retro fitting AC to an older home may be added after the fact, many times in the attic area. A central heating system would mostly have been already in place. Usually a Boiler type system.