what is the energy efficiency ratio of natural gas boiler

Boilers Key Product Criteria | ENERGY STAR

ENERGY STAR partner agrees to sell one or more specific models of boilers that meet or exceed 85 percent AFUE energy efficiency ratings. Residential Boiler: A self contained fuel burning appliance of less than 300000 Btuh energy input for supplying low pressure steam or

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Methods for Calculating CHP Efficiency | Combined Heat and ...

Typical boiler efficiencies are 80 percent for natural gas-fired boilers 75 percent for biomass-fired boilers and 83 percent for coal-fired boilers. The calculation of effective electric efficiency is the CHP net electric output divided by the additional fuel the CHP system consumes over and above what would have been used by a boiler to produce the thermal output of the CHP system.

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