Changing The Spray Nozzle To Fix An Oil Boiler Releasing Black Smoke

1 February 2016
 Categories: Construction & Contractors, Articles


Oil boiler furnaces can save you from the high costs of electric heating if you do not have natural gas lines in your town. However, boilers can be quite finicky and stop working at extremely inconvenient times. You may even see a scary issue every now and then where black smoke or soot seems to billow out from the bottom of the boiler. While this problem may send you into a panic, you may actually be able to fix the problem yourself by changing the oil nozzle. Keep reading to understand what the nozzle does, how the issue happens, and how you can change the nozzle yourself.

Understanding The Oil Nozzle

Your oil boiler fires after a mist of oil and air is forced into the combustion chamber and a small electric spark sets the mist on fire. This mist is the perfect mixture to ensure safe and efficient fuel combustion. A small device called a spray nozzle is responsible for adding the oil to the chamber. This nozzle has an extremely small opening on the end that can become clogged. This is most likely to occur if you have failed to change or clean the oil filter and the oil pump strainer that are responsible for removing the debris from the heating fuel before it gets to the nozzle. Also, a dirty oil tank can cause debris build-up and clogs.

As the nozzle becomes clogged, it will start to drip oil into the firebox. It will also take longer for the oil mist to be created and this keeps the boiler from firing as quickly. When it does fire, the dripped oil ignites suddenly, along with the mist, and black smoke is forced out of the bottom of the boiler before the ventilation system can carry it away through your chimney. If you see smoke and also hear a boom or rumble when the boiler fires, then this is likely your issue. Changing the nozzle should fix the problem.

Changing The Part

Oil boiler nozzles will have different flow rates and spray patterns depending on the make and model of your oil boiler. Information on the type of spray nozzle that your boiler may need should be listed in your manual. You also may be able to see a number and letter combination on the side of the part that indicates which type it is. You will need to remove the nozzle to look for the number. To do this, use a socket wrench to remove the bolts from the front panel or door of the boiler. Open the door and look for a gold nozzle protruding from the back side. This will be the oil spray nozzle and you can remove it by using a wrench to twist it off. 

Look for the number on the side of the nozzle and go to your local home or heating supply store to find a replacement. The replacement nozzle can be twisted into place and tightened with the help of a wrench. If you see rust or dirt inside the firebox as you replace the spray nozzle, remove the debris with your vacuum cleaner. These materials can cause firing and combustion issues that can contribute to the formation of dark smoke. Close the boiler door and tighten the bolts after you complete the cleaning and the nozzle replacement. Restart your boiler and look for dark smoke. If you still see it, then contact your heating specialist right away.

If you do not see smoke anymore, then the problem has been fixed. Make sure to change the filter and clean the pump strainer every year before you start your boiler for the season. Also, clean the very tip of the spray nozzle if you notice that your boiler starts to rumble or take longer to fire than usual. A clean cloth dampened with rubbing alcohol will work well to clean the nozzle. Click here for additional reading about furnace repairs your system may need.