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NORA Oilheat Technicians Manual

• Integration of domestic water heating system • Mass of the boiler or furnace Service procedures have a significant effect on boiler or furnace efficiency. Even the most efficient heating unit will waste fuel if it is not serviced periodically and if it is not adjusted properly. When the full efficiency of the boiler or furnace is not reached, then oilheat’s efficiency advantage is reduced. Routine service using standardized procedures, including vacuum cleaning and precise burner adjustment, are a vital part of good service. Always record efficiency test results. Burner on-cycle heat loss One of the biggest heat losses from central heating systems through the flue is the venting of exhaust gases while the burner is operating. See Figure 16-2. Combustion air and fuel enter the burner at room temperature (usually about 65°F) and heated combustion products leave the boiler or furnace, normally between 400 and 700°F. Heat loss can be reduced by better burner adjustment, clean heat exchanger surfaces, or equipment replacement. Flue heat loss consists of two components; water vapor loss (a fixed property of the fuel) and sensible heat loss (varies with burner adjustment, equipment design and servicing). The “water vapor” of flue loss is a result of the water vapor contained in the combustion of exhaust gases. Water is produced when oil is burned. This water is transformed to steam and leaves the heating unit. Eight-thousand Btus are lost with each gallon of water that is vented as steam—or about 6.5% of the total energy in fuel oil. This loss is also called “latent heat loss” (it is the energy required to convert water from liquid to vapor). It is possible to reclaim the heat contained in the water by lowering the exhaust temperature until the water condenses out of the Figure 16-2: Burner on-cycle heat loss Chapter 16—Energy Conservation 16-5 Combustion test equipment must always be used to adjust the burner for peak efficiency Sensible Heat Loss Depends on Volume of Exhaust Gases Burner Adjustment Affects Sensible Heat Loss Boiler Or Furnace Chapter 16 Energy Conservation Water Vapor Loss Fixed Property of Fuel


NORA Oilheat Technicians Manual
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