Electric heat is in some ways much simpler than either gas or oil, but it can still have its fair share of problems. Set the upper pointer at about 115 degrees Fahrenheit (46.1 degrees Celsius) and the lower one at about 90 degrees Fahrenheit (32.2 degrees Celsius).ĭo not try to adjust the burner of an oil furnace call a professional service person.įinally, we have electric furnaces and heaters. Pointers should be set about 25 degrees apart. There are two pointers on the fan side the blower turns on at the upper pointer setting and shuts off at the lower pointer setting. One side is marked LIMIT don't touch this side. To do this, remove the control's cover and find the toothed dial underneath. If the blower control has been set to ON, change it to AUTO if the blower control is already on AUTO, the limit switch needs to be adjusted. To determine the problem, check the thermostat. If the blower runs continuously, either the blower control on the thermostat has been set to the ON position, or the limit control switch needs adjustment. It also shuts off the blower when the temperature drops to a certain level after the burner has shut off. If the plenum gets too hot, the limit switch shuts off the burner. The limit switch is a safety control switch and is located on the furnace just below the plenum. The draft regulator should be adjusted by a professional service person as part of regular annual maintenance. To decrease airflow, turn the counterweight outward. To increase the airflow, screw the counterweight inward. Too much air in the chimney wastes heat too little air wastes fuel by failing to burn it completely. Accumulated soot and rattling are signs that the draft regulator needs to be adjusted. Centrifugal fans of various types and capacities are used as process fans in power plants depending on the system requirement and industrial process.The draft regulator, located on the stack, is closed when the burner is off but opens automatically to let air into the chimney when the burner is turned on. In power plants, industrial fans play an important role in supplying air necessary for fuel combustion and in the maintenance of furnace temperature. Most common types of gas re-circulation fans are backward curved centrifugal fans. NOx emission levels can be greatly reduced in industrial boilers by recirculating the flue gases from the boiler exhaust duct into the main combustion chamber. These pollutants are produced during combustion process when nitrogen and oxygen react at elevated temperatures. NOx emissions are mostly derived from the nitrogen in the combustion air (thermal NOx). Controlling NOx is critical as it the largest contributor to other types of harmful pollutants. Gas recirculation fans (FGR) are typically used in power plant boilers to reduce the flue gas pollution content in the gases exhausted from thermal combustion processes.įlue gas re-circulation is a highly effective technique that significantly reduces the Nitrogen oxide (NOx) emissions from burners. The most common centrifugal fan used as PA fan is backward curved centrifugal fan. These fans produce a pressure upstream the pulverizer, to push the coal and air mixture through pulverizer into the furnace. In power plants PA fans supply air for conveying of the pulverized coal from coal mills to the furnace area. The main function of the Primary air fan or PA fan is to carry fuel to the furnace for combustion. The most common type of fans that can be used as ID fans are radial fans and backward inclined blade centrifugal fans. Since ID fans can handle hot flue gases, they have more corrosion and erosion problems even when used with Electrostatic precipitators. ID fan creates negative pressure or suction to discharge the gases out after combustion from the furnace. The fan takes hot flue gases from the boiler through dust collector and delivers it to the chimney into the open atmosphere. Induced draft fan is normally located at the outlet between dust collector and chimney. When compared to ID fans, FD fans are easier to maintain and have cleaner operating conditions. These fans have a wheel at the center that is hung on the shaft along with inlet boxes, silencer, filter and rain hood. In power plants, where coal is used as fuel for combustion, FD fans are used as secondary air fans to regulate proper combustion and maximize efficiency of the fuel.Ī typical FD fan arrangement uses inlet and outlet dampers to control and maintain the required air pressure inside the system. The most common centrifugal fans used as FD fans are backward curved and airfoil centrifugal fans. These fans are located at the inlet of the boiler to push high pressure fresh air into combustion chamber, where it mixes with the fuel to produce positive pressure. FD fan or forced draft fan, draws air from the atmosphere and forces it into the furnace through a preheater.
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