Wm. M. Ryan & Co.,Inc.

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System 2000 AFUE Ratings

AFUE ratings lead to inaccurate claims Most conventional boilers claim to be "high efficiency" because their AFUE (government) efficiency ratings are based only on limited testing. AFUE measures only energy wasted from boiler heat that's lost up the chimney. With their short heat transfer passages (some only 16" long, or less) conventional boilers simply can't absorb all the heat they create before it literally goes up the chimney. AFUE accurately records this loss. However there are other more costly inefficiencies that AFUE simply ignores completely.

For Example AFUE does NOT measure::

  • Jacket Loss - Poor insulation on the boiler (usually only 3/4" of fiberglass and that's only on the boiler jacket!) allows heat to escape constantly. This means you're losing heat to garage or basement not heating your home. AFUE doesn't measure it.
  • Standby Loss - Conventional boilers run day and night to keep hot water available, even when no one is using hot water. This is "standby loss," and it's a terrible waste of energy. On a typical hi mass boiler, standby losses are the inevitable result of the need to heat the equivalent of over 1000 pounds of iron, every time the system turns on. AFUE doesn't measure it.
  • Draft Regulator and room air loss sucks warm air out of your home to control chimney draft for the boiler. AFUE doesn't measure it. Note: System 2000 uses outside air for combustion and does not have a draft regulator.
  • Bath, Laundry, Faucets - AFUE doesn't measure how efficiently your boiler makes hot water for bath, laundry and faucets, typically 25 to 35% of your heating costs! AFUE ratings evaluate only energy wasted from boiler heat that's lost up the chimney. Adding up all the common energy losses listed at left, plus the demands of hot water making, reveals the real efficiency ratings of boilers, which are shown in the blue boxes on these pages.

Demand Fired & Cold Start Boilers

While boilers with heavily insulated tanks may store plenty of hot water, they also waste significant energy. Here's why: A tremendous amount of energy is still needed to heat up the 6 to 10 gallons of water and massive amounts of cast iron in conventional boilers. Then, once your hot water needs are met and the boiler shuts off, this heat is wasted. Typically, this will account for about 15 to 20% of your annual fuel bill.

So the logical conclusion is: Don't choose a home heating system based on it's AFUE rating. Instead, inquire about the system's real efficiency rating.

Competing Systems