How To Stop Your Oil Boiler From Making Rumbling Noises

If you own an oil boiler, then you probably know that it is wise to invest in a heating service at least once a year to make sure that blowers, firing components, filters, and oil lines properly work together to create heat for your home. Oil boiler systems are often considered complicated with many parts that need to be adjusted, cleaned, or replaced on occasion. Outside of the heating service you may even need to do some things on your own to make sure that oil is burned as efficiently as possible. This is especially true if your boiler makes rumbling sounds when it turns on. This may mean that too much air is mixing with your oil. The following tips can help you to fix this problem.

Look for Oil Line Leaks

If your oil boiler rumbles when it fires, then this may indicate that there is not enough oil released from the spray nozzle. The spark that lights the oil is then unable to sustain a good flame and you hear noises as the sprayed oil continually tries to ignite. When this happens, oil can sometimes drip down into the combustion chamber and a bang is heard when the dripping oil lights. This often occurs when there are air pockets within the oil line that stop the nozzle from continually spraying oil. You can make sure that air does not get into the oil fuel line by checking and repairing leaks.

Leaks in an oil line are often easy to find, because you will see a small puddle of oil or moisture underneath the break. Inspect the entire length of the fuel line to find leaks. Spend a good amount of time looking for wet spots in areas where your oil line meets your tank and your oil filter. The connections in these areas often loosen.

Replacing Nuts

If you see moisture near one of the oil line connection nuts, then use a wrench to tighten the hardware. Use a cloth to wipe oil away from the oil line and make sure that moisture does not return when you check on the line 15 or 20 minutes later. If one of the nuts continues to leak, then you will need to replace it with a new one.

It is wise to remove the nut from the oil line and find a matching replacement at your local hardware store. Before you remove the nut, make sure to close the valves that allow oil to run to your boiler. Shut the valve that sits near your filter and also locate the one that is attached to your oil tank.

Repairing Holes

If you find a leak within the fuel line itself, then you may need to seek out a replacement oil line. It is wise to speak with your HVAC or heating specialist to complete the replacement. If the hole is small, you can temporarily repair the hole until a more permanent fix can be completed.  

One of the best ways to repair the hole is to use epoxy putty. Spread a generous amount of the putty over the opening in the oil line and make sure to allow the material to cure for a day or more before you let oil run through the repaired line.

Problems with Sludge

If you allow your heating oil supply to run low in your tank before you request an oil delivery, then you may have an issue with sludge. Sludge is the combination of dirt, rust, water, and oil solids that build up on the bottom of your oil tank. This sludge is heavier than your heating oil and it often collects in the tank underneath the oil line opening. This sludge can be disturbed if new oil is placed into your tank when the container is almost empty. The sludge then mixes with the oil and it can run through your oil line.

The oil filter that is attached to the end of your oil line collects this sludge. If the filter fills with the solid material, then the oil flow slows down and the boiler nozzle will not be supplied with enough oil. Too much air then mixes with the fuel and you will hear loud sounds when your boiler starts.

Clean Your Filter

You can easily get rid of the sludge that has made its way through your oil line by cleaning your filter. Shut the oil valve that sits close to the filter first and then look for the bolt or nut that sits on the top cover of the filter. Use a wrench to remove the bolt. The top cover should pop off afterwards. There will be some oil and sludge in the filter casing, so pour out the contents into a bucket. Pull the filter out of the canister afterwards.

If your filter was recently replaced during your last heating service, then the filter probably just needs a good cleaning. Pour a small amount of home heating oil or kerosene into a small container and use the fluid to rinse the sludge from the filter. Once the filter is clean, use a cloth to wipe out the inside of the canister. Replace the filter and the canister cover. Tighten the bolt on the top of the cover and turn the oil valve back on.

If your oil boiler makes rumbling or banging noises in between your yearly service, then fuel oil may not be flowing properly. Checking for oil line leaks and cleaning your filter can help to resolve the issue. If you can't find the problem, get in touch with a heating repair specialist by checking your phone book or visiting a site like