How To Select A Furnace?

 

A central heating system is included in almost every house today. Most houses now are built with combined central heating and air conditioning. Older houses frequently have central heating added, even in rural areas where fireplaces once were a primary heat source. Furnaces are installed alone in some colder regions where cooling is rarely required. There are many considerations in selecting the right furnace, which must be matched to the house for most efficient heating.

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Fuel

Choosing a fuel is the first consideration in selecting a furnace. Natural gas is the dominant source today. It is widely available, inexpensive and clean. Liquefied propane (LP) or "bottled" gas is an option in rural areas not served by natural gas lines. Coal, once a major furnace fuel, is rarely used now but oil, electricity and even wood are other options.

 

Economy

Economy should be considered in choosing a fuel; costs will vary by location. Get prices for various types of furnaces and check the fuel costs for each type. Electricity is an efficient and clean source, but often is more expensive to operate. Oil furnaces often burn less efficiently than other fuels and can produce an oily residue from the exhaust. Oil and LP gas require delivery, often with a fee. Wood furnaces are popular for farm houses and other dwellings where wood is readily available as a "free" fuel

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Efficiency

Look for furnaces rated as high efficiency. All furnaces now have Annual Fuel Utilization Efficiency (AFUE) ratings. An 80 percent gas furnace, for instance, generates heat from 80 percent of the fuel burned. A "high-efficiency" unit will produce heat with 90 to 98 percent of the fuel, dramatically lowering operating expenses. Most of these use electronic ignition to light the flame, rather than a continuously burning pilot light, which consumes energy when the furnace is not active.

 

Size

Finding the right size furnace involves matching the heat output, measured in British thermal units (Btus), with the size of the house. A furnace that is too big for the space will turn on more frequently and waste fuel. One that is too small obviously will not generate enough heat. The heat output also has to be balanced with the ductwork in the house, so it will force enough hot air through the system to heat all the space.

 

Determining Size

If you are replacing a furnace, check the size of the existing unit; increase it if you have added space to the house. Comparing your house to similar homes in the area is another good guide. You can calculate size by measuring the indoor space, number of windows, amount of insulation, height of ceilings and other factors. Use a computer calculating program or a website to guide this. Ask a heating professional for estimates as an alternative.

 

Location

Consider the location of the furnace. Many are installed outside the house walls, but units also can be put in a basement, a garage or an attic. The physical size of the unit can affect the location decision. Location also can affect venting or exhausting of carbon monoxide fumes from heat generation and the air supply needed for combustion; these are not factors with electric furnaces