By taking advantage of the latest technology and installing a new high- efficiency natural gas furnace, you can save energy dollars and improve your home's comfort.

The efficiency rating of a furnace is designated as the Annual Fuel Utilization Efficiency (AFUE). New furnaces have an AFUE from 78 to 90% or higher. The AFUE represents the percentage of fuel turned into heat. The higher the AFUE, the more efficient the unit and more energy dollars you can save. While high- efficiency furnaces (90% AFUE and above) are more expensive than the standard type, the additional cost can often be offset by the increased energy savings, particularly in colder climates or larger homes where annual heating costs are substantial.

New residential furnaces are required to display an EnergyGuide label which compares annual fuel costs with those of other similar sized units.

Some of the advantages of a natural gas furnace are:

• Natural gas is 90% efficient and clean burning
• Provides warm, comfortable air (approximately 125 degrees Fahrenheit) into the home
• Heats your home faster
• Longer life and less maintenance for your air conditioning compressor

Some of the recent developments in high-efficiency furnaces are:

• Electronic spark ignitions or "hot surface" igniters eliminate the need for continuously burning pilot lights which waste fuel and increase operating costs.
• Induced draft uses a small fan to draw combustion air through the system, reducing the amount of air needed for safe combustion and improving efficiency.
• Outside air intakes for combustion air (the air that is mixed with the gas as it burns) ensure safe, efficient operation even in very tight homes with low ventilation rates.
• Condensing furnaces (90% AFUE and higher) incorporate an additional heat exchanger and extract enough heat from the combustion gases that moisture in the gas condenses, releasing additional useable heat. Exhaust gases from a condensing furnace are cool enough that they are vented through a wall with plastic piping.
• Pulse furnaces burn gases in small explosive pulses, much like an automobile engine. Pulse combustion allows the maximum amount of heat to be extracted from the burning fuel. These furnaces can achieve AFUE ratings as high as 97%.
• Automatic vent dampers close the flue pipe when the burners are off and reduce the amount of heated inside air drawn up the chimney.

Installing a new high-efficiency boiler can save energy and dollars while improving comfort in your home.

Boilers that are well-maintained can last as long as 30 years. However, the life of a boiler can be severely shortened by poor maintenance. If your boiler is very old or has not been well maintained for many years, you should consider replacing it with a new high-efficiency boiler. High-efficiency boilers are much less expensive to operate and will save you money all winter long.

The Annual Fuel Utilization Efficiency (AFUE) rating indicates what percentage of the energy in the fuel is converted into usable heat. New high-efficiency boilers can have AFUE ratings of 87% or greater while older boilers typically have AFUE ratings from 50% to 75%. If your boiler has not been well maintained, its efficiency could be further decreased.

New high-efficiency boilers incorporate one or more of the following improvements to increase their AFUE.

• Power burners mechanically mix gas and air and inject the mixture into the combustion chamber. A small motor drives a blower which draws in combustion air from the surroundings. The air and gas are mixed and injected at line pressure. A positive pressure is produced inside the combustion chamber insuring proper draft through the boiler. Since these burners closely control the air/fuel mixture, they tend to be very efficient.
• Electronic spark ignition ignites the pilot light only when heat is demanded. When the device is energized, an electrode creates a spark that ignites the pilot. The pilot then ignites the burner. Eliminating the constantly-burning pilot can save several dollars each month.
• "Hot surface igniters" eliminates the pilot light altogether. The igniter is energized electrically and quickly attains a very high temperature. When the gas valve opens, the gas is ignited by coming into contact with the hot surface igniter.
• Vent dampers prevent heat from escaping up the chimney when the main burner is off. By preventing the escape of heat during the "off" cycle, a vent damper can also increase the furnace's operating efficiency by minimizing "cold" starts. At the beginning of each "on" cycle, the unit's efficiency gradually increases until it reaches steady-state. The time needed to reach this point is reduced as a result of the vent damper. Because any air vented up the chimney or flue must be replaced by outside air, vent dampers can also help reduce infiltration.
• Recuperative/condensing boilers recoup most of the heat from the flue gases. This is accomplished through the addition of a secondary condensing heat exchanger. So much heat is extracted that the water vapor in the gases condenses, giving them the name condensing boilers. The exhaust gases from these types of boilers have lower temperatures and can be vented horizontally, eliminating the need for a chimney.

Contact your heating service company to do a thorough evaluation for you. They should be able to estimate how efficiently your existing boiler is performing, its useful life, and whether replacing it with a new, properly sized, high efficiency unit makes sense.