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Understanding Combustion in Gas-Fired Equipment
Natural gas is combined with oxygen to fuel the combustion process - releasing energy, in the form of heat, to raise the temperature of water entering the unit. The combustion process also generates carbon dioxide and water vapor as well as pollutants. These byproducts then travel through the heat exchanger before being released "up the stack" of gas-fired boilers and water heaters.
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Condensing Flue Gases
Water vapor, which is a by-product of the gas-fired combustion process, contains significant energy. For every pound of water vapor that is forced into a liquid state some 1,000 BTUs of latent energy, in the form of heat, is released. This change of state is called "condensing."
Effective condensing increases the efficiency of the boilers and water heaters by about 10% -- turning more of the unit's fuel into usable heat. What's more, condensing occurs naturally -- when the vapors cool below their dewpoint which is typically 135°F. By flowing cold water (<130°F) into the heat exchanger, AERCO boilers and water heaters automatically begin to condense to yield greater efficiencies.
Many Manufacturers Discourage Condensing Applications
When latent energy is extracted from the water vapor, acidic condensate remains on the surface of the heat exchanger. Unless the heat exchanger has been built from the highest quality materials of construction and is designed to drain freely, condensate will damage and destroy it over time.
Most manufacturers discourage applications which leverage this incredibly energy efficient process. And although they test and rate their efficiency under condensing conditions many warranties will not cover heat exchanger damage in applications using <140°F return water.
Non-condensing equipment is typically manufactured from less expensive materials (copper, cast iron, carbon steel, etc.) and must rely on ancillary components to protect the boilers and water heaters. Such conventional applications require dedicated boiler pumps, mixing valves and temperature averaging components to pre-warm water entering the unit above 140°F.
AERCO's Approach
AERCO uses the highest quality materials of construction in its gas-fired boilers and water heaters. Performance-proven to withstand the potentially damaging effects of condensate, we aggressively encourage heating system designs which utilize cooler water temperatures to promote condensing. Our customers get more useable heat from the energy they buy in addition to a streamlined heating plant with fewer parts to power and maintain in the long-run.
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