A condensing boiler is a type of water heater that is typically used for heating systems fueled by gas or oil. It is designed to increase fuel efficiency and reduce wasted energy by reclaiming some of the energy that goes up the chimney. When a boiler burns natural gas, carbon dioxide and water vapor are created as a by-product of the combustion process. One of the hot gases produced in the combustion process is water vapor (steam), which arises from burning the hydrogen content of the fuel. A condensing boiler extracts additional heat from the waste gases by condensing this water vapor to liquid water, thus recovering its latent heat of vaporization. This water, along with acidic byproducts of the fuel combustion process, are then drained out of the boiler and into a neutralizer. The key features of a condensing boiler include:
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Efficiency: A heating system can achieve high efficiency (greater than 90%) when operated in the correct circumstances.
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Heat exchanger: A condensing boiler uses a heat exchanger to capture and recycle heat from the exhaust gas before it’s vented.
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Condensation: By condensing the water vapor, the heat recovered is fed back into the heating system, reducing the heat wasted up the chimney (or out the vents), as well as reducing the fuel required to heat the water being drawn into the boiler.
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Materials: Most condensing boiler heat-exchangers are made from stainless steel or aluminum/silicon alloy because the condensate is corrosive to mild steel or cast-iron components of a conventional high-temperature boiler.
Condensing boilers are smaller and lighter than non-condensing boilers, and typically wall-mounted. They are also more energy-efficient than non-condensing boilers, which means lower gas utility bills and a smaller carbon footprint.
