How to Remove the Oil Furnace Firing Assembly for Maintenance-Part 1

What You'll Need
Adjustable wrench
Paint brush
Clean rags
Paint thinner
Oil container

The key to the efficient operation of an oil furnace is its firing assembly. An oil furnace creates heat when its electrodes ignite a mixture of oil mist and air that is sprayed into its fire chamber by the firing assembly. A malfunction of any of these components will prevent the furnace from generating the degree of heat it is supposed to generate. This malfunction can happen because one of these components is broken or worn. When this happens to your oil furnace, you can often repair the furnace by replacing its firing assembly or by cleaning or replacing the spray nozzle inside the assembly. To do either, you'll need to remove the firing assembly from the furnace. To remove and repair the firing assembly in your oil furnace, follow the simple guidelines below,

Step 1 – Remove the Assembly

Your oil line connects to the assembly. Remove this line so it doesn't leak oil it is detached. To remove the assembly, unscrew the bolts that hold it in place. Maneuver it out of its position in the furnace. You'll need to be careful in moving it past the electrodes mounted on the holding chamber sides. Any damage to these electrodes from hitting them with the assembly can prevent it from working properly.

Step 2 – Clean the Spray Nozzle

Check the assembly you've removed for a nozzle. There might (or might not) be a housing installed over the nozzle that preventing you from removing the nozzle. If you see this kind of housing, you'll need to remove it and set it where you'll be able to reach it when you're ready to re-attach it. Locate the hex nut holding the nozzle in place. Use one wrench to unscrew this nut, while with a second wrench you hold the oil line connector from turning. If you inadvertently twist this line, the twisting can easily break the line.

Step 3 – Clean the Components

Take the components you have removed and clean them with a brush or cloth in the paint thinner. While cleaning, pay particular attention to the openings in the nozzle that may have become clogged. If the clogging is not removed -- your furnace will not fire as it should.

Step 4 – Check the Nozzle Rating

On the head of the hex bolt, that holds the nozzle in place, you'll find a rating. If the nozzle rating shows 15 gallons per hour (GHP), you'll need to replace the nozzle. When all clogs are removed from the nozzle and all parts are cleaned, dry them off. Examine all the parts for excessive wearing or breaks. If you find broken parts, replace them before re-installing any of the assembly pieces. Check your furnace manual parts list so that any you replace will fit with your particular furnace model.

Step 5 – Re-Install the Assembly

Now that all the broken or worn parts have been replaced and are clean, re-install them into the assembly.  Again, be cautious in maneuvering past the electrodes. Tighten any bolts or clamps holding the assembly in place, and reattach the oil line.