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NORA Oilheat Technicians Manual

Savings For Every $100 Fuel Costs by Increase of Combustion Efficiency Assuming Constant Radiation and Other Unaccounted-for Losses From an Original To an Increased Combustion Efficiency of: Efficiency of: 55% 60% 65% 70% 75% 80% 85% 90% 95% 50% $9.10 $16.70 $23.10 $28.60 $33.30 $37.50 $41.20 $44.40 $47.40 55% — 8.30 15.40 21.50 26.70 31.20 35.30 38.90 42.10 60% — — 7.70 14.30 20.00 25.00 29.40 33.30 37.80 65% — — — 7.10 13.30 18.80 23.50 27.80 31.60 70% — — — — 6.70 12.50 17.60 22.20 26.30 75% — — — — — 6.30 11.80 16.70 21.10 80% — — — — — — 5.90 11.10 15.80 85% — — — — — — — 5.60 10.50 90% — — — — — — — — 5.30 Chapter 16—Energy Conservation 16-11 air depends upon on-cycle airflow through the heating unit (boiler-burner or furnaceburner design). If the unit is outside or is in a non-heated portion of the home that has plenty of excess air, air infiltration is not important. Air infiltration loss is greatest for heating appliances that operate with large quantities of excess combustion air, units with air leaks into the heat exchanger, or units that have large off-cycle airflows. Efficient boiler-burner or furnace-burner combinations will operate with low air infiltration losses. Air infiltration heat loss for oilheating systems is usually about 2% of the total fuel energy, but some studies indicate that it can be as high as 12%. This figure is considerably higher for propane and natural gas-fired heating units, and it is one of the efficiency advantages of oil-fired equipment. The best solution for air infiltration is isolated combustion, whereby outdoor air is piped directly to the burner air intake. In summary New, highly efficient oilheating units transfer more than 85% of the fuel energy directly to the home. Old units may operate in the 60 to 76% range. See Figure 16-7. Equipment modifications to improve efficiency New oil boilers and furnaces are often more efficient than their gas counterparts. While older oil boilers and furnaces are less efficient than the newer units, they can be “modernized,” and their operating efficiencies can be improved. Heating system modifications to improve efficiency range from low-cost adjustments such as adjusting for proper combustion and sealing excess air leaks to equipment replacements such as installing new flame retention oilburners or new boilers or furnaces. The table below summarizes the efficiency gains from those improvements. This next section will identify a number of equipment modifications that save energy. These are: • Flame retention burners • Replacement boilers or furnaces Chapter 16 Energy Conservation


NORA Oilheat Technicians Manual
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