Boiler System Energy Losses

The Boiler Efficiency Calculator takes into account only major energy losses‚ which typically represent 10 to 20% of fuel input. The major energy losses associated with boilers fall into two categories: stack losses‚ and radiation and convection losses.

Stack Losses

Stack losses represent the heat in the flue gas that is lost to the atmosphere upon entering the stack. Stack losses depend on fuel composition‚ firing conditions and flue gas temperature. They are the total of two types of losses: Dry Flue Gas Losses – the (sensible) heat energy in the flue gas due to the flue gas temperature; and the Flue Gas Loss Due to Moisture – the (latent) energy in the steam in the flue gas stream due to the water produced by the combustion reaction being vaporized from the high flue gas temperature. They are addressed by assuming typical fuel analyses and a few reasonable assumptions that simplify calculations.

For more details on how stack losses are calculated‚ refer to a description of the methodology based on the type of fuel fired in the boiler system. If your fuel type is not listed below‚ refer to the general stack loss methodology.

• General Methodology
• Natural Gas
• Light Fuel No. 2 Oil
• Light Fuel Oil (Diesel) Low Sulphur
• Heavy Fuel No. 6 Oil
• Heavy Fuel No. 6 Oil Low Sulphur

Radiation and Convection Losses

Radiation and convection losses are independent of the fuel being fired in a boiler and represent heat lost to the surroundings from the warm surfaces of a boiler or high-temperature water generator. These losses depend mainly on the size of the equipment (e.g.‚ small boilers have a proportionately larger percentage loss than large boilers)‚ and the actual output relative to the maximum design output. More details on calculating radiation and convection losses are available at Radiation‚ convection and other losses.

Disclaimer: The Boiler Efficiency Calculator (BEC) produces results which are based on simplifying assumptions‚ primarily with respect to fuel composition, and are only intended for general information purposes. The results should not be used to determine efficiency for contractual purposes‚ such as for boiler acceptance tests. BEC is not intended to serve as a guide to be used in investment or other commercial activities. The authors and Natural Resources Canada make no warranty of any kind with respect to the content and accept no liability, be it direct, consequential, financial or otherwise, arising from, or related to, the use of this information.