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NORA Advanced Efficiency

Chapter 2 What is Efficiency? What is Efficiency? This chapter covers the various ways heating systems lose heat and defines the different efficiency terms used to describe heating system operation. The purpose of oil-powered heating systems is to release the energy contained in the fuel and convert that energy into useful heat in the building. No heating system can operate without some heat losses. Part of the energy contained in the fuel is lost before it can be delivered as Efficiency The actual efficiency of an oilheating system is affected by the following: • The efficiency of the burner-boiler or burner-furnace • Chimney design and upgrades • Installation practices, including: boiler or furnace sizing, boiler water or furnace air operating temperatures, piping or ducting design, sealing, and insulation, and source of combustion air • Service procedures, such as: barometric damper setting, sealing air leaks into the boiler or furnace, burner adjustment (excess air and smoke), cleaning boiler or furnace heat transfer surfaces as needed, and proper nozzle sizing • Other factors that affect efficiency: building design and construction, location of unit in the building, chim- ney draft, zoning of the distribution system, and the domestic water heating system 10 National Oilheat Research Alliance useful heat to the radiators or registers. The efficiency of the heating system is simply the percentage of the fuel’s energy that is delivered to the living space of the building—the lower the heat losses, the higher the system’s efficiency. Many heat losses occur in a typical heating system, starting when the pump delivers the fuel to the burner up until the heat reaches the living area. Some of these depend on the design of the burner, furnace, boiler or water heater, the venting system and distribution system. Additionally, how the system is installed, adjusted and maintained will also affect the efficiency. Finally, how well the building envelope is sealed and insulated determines how long the heat created by the heating system stays in the building. Types of Heating System Heat Loss Heating systems lose heat in five ways, Figure 1: 1) on-cycle flue heat losses (losses that occur while the burner is running) 2) off-cycle flue heat losses (losses that occur when the burner is off) 3) jacket heat loss from the boiler, furnace, or water heater casing 4) distribution heat loss from the steam or water pipes and air ducts 5) infiltration heat loss from cold outdoor air being drawn into the building as a result of the operation of the furnace, or boiler.


NORA Advanced Efficiency
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