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NORA Oilheat Technicians Manual

2-6 Heating Oil and Its Properties Color Heating oil is dyed red to differentiate it from on-road diesel fuel for tax compliance reasons. Problems with the fuel are not indicated by the darkness of the color. A murky appearance, however, may indicate a fuel quality problem. Fuel related service calls The oilheat industry’s top two service priorities are improved reliability and reduced heating equipment service costs. A significant number of unscheduled no-heat service calls are caused by inconsistent fuel quality, fuel degradation, and contamination. Heating oil varies during the season. Wholesalers get their product from around the world, from Malaysia to Texas. Each of these products is slightly different; as a result, the product in the customer’s tank may be a mixture of a variety of fuels. A great deal of our product is created by blending various fuels together to meet the rather loose definition for #2 heating oil laid out in the ASTM D 396 specification. Additionally, over time, fuel degrades— water may enter the system and bacteria have an opportunity to grow. Good housekeeping, installing filters on all customers’ burners, and an aggressive problem-tank replacement program can cut fuel related service calls dramatically. Potential problems in the tank The population of oil tanks in the field is aging. As the tanks age, rust and sediments build up in the tank. Secondly, oil has a finite shelf life and breaks down over time. The third problem is the size and speed of delivery. Filling a tank kicks-up all the sediments and rust in the bottom of the tank, and that leads to plugged lines, filters and nozzles. The solutions here are not to let the level of oil in the tank get too low, to slow down the pumping speed of Good housekeeping, installing filters on all customers’ burners, and an aggressive problem-tank replacement program can cut fuel related service calls dramatically. performance will be affected until the fuel warms. As stated in the Nozzle Chapter (Chapter 5), cold oil causes poor atomization, delayed ignition, noisy flames, pulsation, and possible sooting. Water and sediment Accumulation of water in tank bottoms is undesirable, since it leads to the formation of sludge and ice. Sludge is largely oil and water. Water and oil usually do not mix, but if organic sediment is present in the fuel, it acts as a binder to stabilize the mix of fuel and water. This forms a white milky substance that will not burn. The ASTM limit for water is 0.1%, but most fuel sold has much less water. Unfortunately, water can get into the system from condensation, leaks in lines, or missing vent and fill caps. Sulfur content Sulfur exists in varying degrees in all fossil fuels. The sulfur content of heating oil ranges from 0.5% to 0.05%; the ASTM maximum is 0.5%. When the sulfur burns, it mixes with oxygen and forms sulfuric dioxide. It also creates a small amount of sulfur trioxide. The sulfur trioxide reacts with the water vapor in the combustion gases to create a sulfuric acid aerosol. If the acid condenses (at 150-200°) it adheres to the heat exchanger, flue pipe and the inside of the chimney. It creates a scaly yellow to red colored crust. Scale makes up 50% of deposits on the heat exchanger. It downgrades efficiency by 1% to 4% over the year. It also blocks flue passages, restricting air flow and increasing smoke and soot. Using low sulfur fuel all but eliminates scale and soot formation on heat exchanger surfaces. The efficiency does not degrade over the heating season, saving energy. It also results in decreased appliance service. Chapter 2 Heating Oil


NORA Oilheat Technicians Manual
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