Boilers

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Introduction

Heating and cooling typically accounts for 30 to 40% of your annual energy bill. Next to furnaces, boilers are the second most common heating system in the United States, although they are less common in California. (Only about 2% of California homes use boilers.) A boiler uses either natural gas, oil or electricity to heat water or produce steam, which is circulated through a network of pipes into radiators, baseboard convectors, radiant floors or fan-forced coils. Conventional, older boiler systems may only be 60% efficient. By upgrading to a new boiler, you could save considerable amounts of money on heating throughout the life of the new equipment.

Technology Options

Boilers can be hot water or steam, and either type can be gas or oil boilers. The piping systems are different for each type. The hot water system boiler uses a pump to circulate the hot water while the steam boiler uses its own pressure to circulate the steam throughout the system. Both use a burner to heat the water to the temperature that is set on the thermostat. An aquastat monitors the temperature of the water and turns the burner off when the temperature reaches the desired level. Steam boilers must heat the water to a higher temperature, and therefore have lower efficiencies than hot water boilers. Natural-gas-fired boilers are more efficient than oil-fired boilers.

Combination boilers combine water heating and heat generation in one unit and can save considerable money on heating and water heating costs. The heating part of the "combi" boiler works in the same fashion as other boilers. For more information on water heating, visit the Water Heater Product Guide.

Boilers can achieve greater efficiency with improved features, such as:
  • Electric ignition, which eliminates the need to have the pilot light burning all the time.
  • New combustion technologies, which extract more heat from the same amount of fuel.
  • Sealed combustion, which uses outside air to fuel the burner, reducing draft and improving safety.
  • High-efficiency pumps for moving heated water through the system.


Efficiency Ratings
The efficiency of new boilers is measured by the annual fuel utilization efficiency (AFUE), a measure of overall performance. The federal minimum-efficiency standards for boilers took effect in 1992, requiring that new boiler units have an AFUE of at least 80%. In comparison, many older boilers have AFUE ratings of only 55 to 65%. Some of the highest-rated units are natural gas-fired, with AFUE ratings as high as 99%. ENERGY STAR publishes a list of the most energy-efficient gas and oil boilers of various sizes on its website.

For more information, visit the American Boiler Manufacturers Association and the Plumbing-Heating-Cooling Contractors Association.

Efficiency Benefits

ENERGY STAR qualified boilers have an annual fuel utilization efficiency (AFUE) rating of 85% or greater when properly sized and installed. They use approximately 10% less energy than today's standard boilers. You could save up to 30% on heating bills by replacing a 10-year-old boiler with a new ENERGY STAR qualified boiler. By combining your investment with advanced controls such as programmable thermostats, you can save even more.

Manufacturers

Burnham Corp., and Carrier Corp. are two of the manufacturers of ENERGY STAR qualified boilers.

For a complete list of ENERGY STAR manufacturer partners, visit the ENERGY STAR website.

Purchasing Tips

  • Before buying a new boiler, make every effort to improve the energy efficiency of your home. These improvements will save money on heating your home by reducing loss of heated air to the outside, and will reduce demand for heating on your boiler. Consider looking at the efficiency of your windows and the quality of your insulation in both your ceiling and your walls and around your delivery pipes.
  • Size your new boiler accurately to realize maximum savings. Have a contractor do a heat-loss, heat-gain calculation to ensure that the boiler you purchase is the best one for your home. Among other important considerations, make sure that the calculation takes into account:
    • Size and configuration of the house
    • Levels of insulation in walls, ceilings and second floors
    • Number and type of windows in the home
    • Orientation of the home to the sun
  • Evaluate the cost-effectiveness of a new boiler. If you have an older boiler in your home, it is cost-effective to upgrade it to the 80%, 90% or higher AFUE level if the difference in boiler price is not more than the amount you will save over its lifetime.
  • Look for the ENERGY STAR. When you buy ENERGY STAR qualified boilers you know that you are getting one of the most efficient models available.