Oil Furnace Warning Noises, What They Mean and How to Fix Them

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Recent energy use surveys nationwide show that today, more than half of Canadian homeowners use electric, natural gas or propane heating systems.

But according to Natural Resources Canada, as many as 39 percent of Canadian homeowners may use oil as their primary source of heating fuel.

Here in Ontario, approximately 9 percent of homeowners rely on oil as their primary source of home heating fuel.

But just because oil-fired furnace systems are still relatively common throughout Canada doesn’t mean they are any less mysterious when they start to “talk” to you in grumbles, grinds, clanks or clatters!

In this blog post, we review common oil furnace noises, what each one means and what steps to take next.

7 Common Oil Furnace Warning Noises

All furnace systems have their own unique “language.” They can’t talk to you in words, so they use sounds—knocking, clattering, whistling, grinding, screeching, rumbling, random cycling—and each one of these sounds has a message to communicate if you know how to decipher it.

1. Knocking

After running to the front door a few times, you will probably figure out that the knocking sound isn’t coming from a neighbor who has popped by for a visit.

When your oil furnace knocks, the most common reason for this is that there are air bubbles trapped in the lines.

The only solution to resolve the knocking sound is to do something called “bleeding the lines.” As the name suggests, this repair involves draining the lines to remove the trapped air.

2. Clattering

A clattering sound often points to loosened components that are coming into contact with each other as the furnace cycles on and off.

The most common culprit for clattering noises is actually the access panel, which makes sense, since this panel is the most frequently accessed part of a furnace.

Tightening the panel can fix this minor issue handily.

3. Whistling

If your oil furnace begins to emit a shrieking or shrill whistling sound, this frequently points to a problem with air flow. For example, your furnace filter may be damaged, dirty or blocked.

If your furnace filter is a disposable one, this is a good sign it is time to replace the filter. For the reusable filter, take it out and clean it, and then replace and test it to make sure the sound is gone.

4. Grinding

Grinding noises coming from the direction of your oil furnace are never good news. In nearly every case, they indicate a part has worn out and needs repairs or a replacement. When you hear grinding, always shut down your furnace until a diagnosis can be made.

One frequent cause for grinding sounds is worn-out bearings. Because of the location of these bearings, it is best to contact a professional for repair assistance.

5. Screeching

Screeching, squealing or whining can indicate a belt has been stripped or has slipped out of place. These types of sounds can also indicate a problem with the blower motor.

A worn-out or damaged belt may need to be replaced before you can use your oil furnace safely again. Sometimes just adjusting the belt tension will repair the issue. For suspected blower motor issues, it is always best to contact a technician for an evaluation.

6. Rumbling

A rumbling sound emanating from your oil furnace is usually created by a dirty burner or a malfunctioning pilot light. If oil or dirt has built up around the burner, this can cause rumbling noises as it burns away. If the pilot light is having trouble doing its job, you may also hear the rumbling as it tries again to stay lit.

The best option here is to contact a professional to have them come out and clean the unit and test the pilot light to make any necessary repairs.

7. Random Cycling

If your oil furnace starts to make sounds like it is cycling off and on at odd intervals, there may be an issue with the air filter. Another possible cause can be a problem with the thermostat.

In either case, if you can’t visually detect anything amiss with the filter or the thermostat, the right choice is to contact a technician for a diagnosis.

When Your Oil Furnace Starts to Smell

It is worth mentioning that sounds are not the only communication tools your oil furnace uses to get your attention.

Odours can also be an indicator that something is not right with your furnace components or operation.

Among the most concerning and scary odours are smoke and burning smells. These nearly always can be traced back to a problem with the burner, the pilot light or the fuel nozzle, although there are other potential causes to look at as well.

Because odours can also arise from problems with the fuel lines, chimney liners and even furnace sizing issues, when your nose detects a new odour and the oil furnace is the prime suspect, call a technician right away and don’t use your oil furnace again until they can diagnose the cause and repair it.

High-Efficiency Oil Furnace Systems

Since 1998, Canada’s Energy Efficiency Regulation has required that all oil furnace systems maintain a minimum of 78 AFUE (annual fuel utilization efficiency).

The new breed of high-efficiency, space-saving oil furnace systems feature high-performance burners, fully insulated cabinets and silencer baffles for quiet, efficient, affordable heat all winter long.

We are proud to carry both the Bryant Preferred Series and the Bryant Legacy Series of oil furnace systems. These new high-efficiency systems can deliver up to 86.6 AFUE—well above the nationwide minimum standard.

Get in Touch

Is your oil furnace making mysterious noises or emitting strange smells that have you concerned? Our highly trained, polite and prompt technicians at Shipton’s Heating & Cooling LTD service all makes and models of oil furnace systems.

Contact us online or give us a call at 905-549-4616.

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