Electronic Control Board for an Electronic Ignition Gas Furnace
Electronic ignition for gas furnaces is the modern way for furnaces to light the main burners on modern gas furnaces. Electronic ignition gas furnace technology has evolved from the standing pilot gas furnace ignition systems that continue to be used today however there are less and less standing pilot gas furnaces used today. If your furnace is not working and you want to troubleshoot an electronic ignition gas furnace system it is important to make sure you know which type of ignition system you have for your furnace. Additionally there are different types of electronic ignition gas furnace systems and it is important to differentiate between the types of electronic ignition systems before troubleshooting a gas furnace electronic ignition. We will break it all down for you in this series article: “Troubleshooting an Electronic Ignition Gas Furnace“.
More on gas furnaces and electronic ignition here.
Oil burner oil filters are important to keep trash out of the burner gun and plugging the nozzle. A dirty filter can also choke the system from firing properly by preventing the correct amount of oil flow from reaching the nozzle. Oil furnace oil filters or oil 
The oil burner and oil controls provides the main source of heat for this oil furnace. The oil burner comprises of an oil pump, a burner electric motor, a burner blower, a step-up transformer, an oil ignition control, an oil burner gun and oil nozzle(inside not viewable here). The burner electric motor is directly linked to the blower and the oil pump and when the electric motor starts (controlled by the ignition control) the pump begins pumping oil while the blower provides primary air to the combustion chamber.
Standing pilot gas furnaces and water heaters are still around today even in newer homes. All the major hardware stores and HVAC dealers carry standing pilot appliances although a new standing pilot gas furnace or 
This Oil Furnace has flue gas condensation problems as one can see from the white residue forming on the front of this oil furnace. This problem occurs when the flue gases are not hot enough to rise above and out of the flue. The flue gases from the oil furnace are condensing and the residue which is highly caustic is dripping back down the flue and around the furnace. The cause of this problem is likely because the oil settings are not correct. The oil burner is providing either too much air to the combustion chamber or too little air to the combustion chamber and either of these can cause the flame temperature to be too low and lack the heat necessary to carry the flue gases out and away from the flue. An adjustment can be made using a combustion analyzer to ensure the proper amount of air is introduced into the combustion chamber to ensure the correct combustion process. Using a combustion analyzer one can also test the amount of O2, CO2 and CO along with other factors that make the combustion process efficient and safe. The caustic properties for the flue gas condensationwill likely cause the furnace and the flue to rot prematurely.
This Honeywell oil burner ignition control controls the oil burner sequence of operation. On a call for heat from the thermostat the oil burner ignition control starts the burner blower. this mechanically interlinked with the oil pump. The blower blows air into the combustion chamber and the oil pump pumps oil to the burners oil nozzle. The step up transformer is energized and applies a very high voltage spark to the burners ignitor. When the flame is detected it is immediately detected by a cad cell eye which recognizes the light produced by the flame inside the combustion chamber. After the cad cell eye detects the light from the flame it signals the oil burner ignition control that all is well and to keep things going. The oil burner will continue to produce a flame until either the cad cell eye determines there is no flame or the thermostat satisfies and stops the call for heat. If its the thermostat stopping the call for heat the oil burner ignition control stops the blower and the fire in the combustion chamber goes out. The blower in the furnace, which blows air through the ductwork and delivers it to the vents in the home, continues to run. This makes use of the residual heat left over inside the heat exchanger and allows things to cool off. The fan on an oil furnace usually shuts off based on temperature. When the temperature inside the heat exchanger cools down to a certain setpoint it shuts off the blower.
