Combi Boilers Explained
Some homeowners purchase combination boilers, or combi boilers, for their heating efficiency and low installation costs. Combi boilers offer central heating and water heating capabilities from the same energy source. This type of boiler is more commonly seen in continental European homes than houses in the United States. When installing a combi boiler, some factors to consider are: safety issues, outdoor climate and local building code requirements. Does this Spark an idea?
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Operation
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A combi boiler circulates hot water from its water heater and passes the hot water through a heat exchanger in the unit's air handler. From there, the combi boiler's blower emits heated air into the home's duct and vent system, which, in turn, spreads heat throughout the house. Homeowners can also connect their air conditioners to the combi boiler's exchanger for summer use. The operations of cooling and heating a house are similar with combi boilers; rather than blowing hot air, combi units emit cool air through the duct and vent system when connected to air conditioners.
Water Heaters
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Combi boilers use tankless coil and indirect water heaters. Tankless coil units heat water with a coil or heat exchanger instead of storing heated water in a tank. These water heaters work best in the winter when the heating system is used regularly, according to the U.S. Department of Energy. The Department also says indirect water heaters are more energy-efficient and less expensive for most homes. However, indirect water heaters require water storage tanks to operate. Indirect water heaters use a combi boiler's main furnace to heat water from the storage tank's heat exchanger.
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Benefits
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Using a combi boiler is economically and environmentally beneficial. Combi boilers reduce the amount of energy needed to heat a house, and they do not produce as many pollutants as other boiler types. According to the energy-efficiency consultant firm, Frontier Associates, combi boilers are able to reduce utility costs by 15 percent compared to standard boilers. Also, homeowners do not have to install or pay for separate water and space heating units. Combi units also require less maintenance than standard heaters.
AFUE
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The efficiency of boilers is determined through the Annual Fuel Utilization Efficiency, or AFUE, measurement. A boiler's AFUE measures how much fuel the unit converts into space heat in proportion to the amount of fuel entering the boiler. The efficiency for combi boilers is measured by its CAafue, or Combined Appliance Annual Fuel Utilization Efficiency. However, a combi boiler's CAafue only applies to the efficiency of the unit's space heater. A combination boiler's CAafue is usually measured in percentages.
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