An oil fired furnace needs more maintenance compared to propane or gas furnaces. One would say that it would be safe to go 3 years and not service the furnace, but that would be inadvisable. Failure could result from cracks in the electrode insulator, and this causes the electrode mount to melt. It would therefore be safer to just maintain them annually. Cleaning or servicing an oil fired furnace is no big deal and you do not need some degree to do this. However, it can be messy.

You want to start by turning off the power and then removing the burner assembly. This part has the electrodes on it. It all depends on the type of unit and how you remove the assembly. You can determine this by trailing the oil line from the pump to the furnace. You should get a clue as to what oil fired furnace you have. Most of the time you are required to remove the voltage transformer or hinge it back to get to the assembly. Replace the nozzle once you have it out. It has to be replaced with one that gives the same spray pattern.

Wipe the assembly down to remove the oil and tarry residues. You also need to gap and position the electrodes, but before you do this inspect them. Any cracked ones should be replaced. The ones with pitted and eroded ends should be replaced, too. Replace anything if you are in doubt. Don’t neglect anything in the oil fired furnace, because you are only going to have to come back to it later. There is a tool that is required to gap the electrodes. This tool you will be able to pick up at a supply store. Do not attempt to do this without the tool! You could cause a fire and wreck the oil fired furnace if not gapped properly.

Once you have this out the way, take a cloth and clean all air passages that lead to the oil fired furnace. Clean the squirrel cage gating your combustion blower. Clean your oil pump, transformer’s electrodes and the transformer. Check for the flame sensor. This is found on some units. Clean this.

Put the whole thing together and ignite the oil fired furnace. The flame should be quiet and instant. No sound and no delays. If everything was done correctly, the oil fired furnace should just start.

Now you must adjust the airflow to the furnace’s flame. Uncover its inspection port and the flame should be there. Turn down the airflow so you are left with a smoky and dull-yellow flame. Now increase the airflow until the smoke disappears and the flame turns bright yellow. A lean flame will be bright with a tinge of blue. This means that the flue is taking too much air. Once you close the inspection port, if the oil fired furnace shudders and the flame roars, back the air off until it stops. Make sure the flame isn’t smoky.