Have you noticed that your furnace started making unusual sounds? If so, it is worth looking into, since the noises are a clear indication of problems. Be aware of these three noises and what is causing them.
Scraping or Grinding
Does it sound like there are grinding wheels inside your furnace? It may be producing a sound that is similar to fingernails that drag across a chalkboard. These sounds can be caused by a blower wheel inside the furnace. A common problem is a blower wheel that came loose and is no longer seated properly on the motor shaft. The wheel may also have a crack in it and need replacement.
Regardless of what is causing the noise, it's most likely a problem you can't fix yourself. An HVAC specialist can order and replace the damaged parts for you. At the very least, they can inspect the problem and secure the part back where it is supposed to go.
Have you noticed a banging sound when turning on the furnace? If so, it's most likely due to a dirty burner in the furnace, which is causing a delay with igniting the burner. Extra gas accumulates inside the furnace, and when the burner ignites, there is a tiny explosion inside the furnace that creates that banging sound.
This problem can be fixed on your own if you want to attempt a DIY repair. You'll need to gain access to the burner so that you can clean it off. There will most likely be debris and ash on the burner, which needs to be wiped off using a slightly damp cloth. Once the part dries, you can turn the furnace back on and see if the banging sound no longer occurs.
Is there a noise that sounds like metallic tapping while the furnace is on and off? This can be from the air ducts that are contracting and expanding as heat flows through the system. This is a problem that can be solved by adding insulation around the air ducts in places that are exposed, which should cause the air ducts to not change temperature as much.
Whenever you are experiencing an odd noise from a furnace, it is best to have it inspected by a professional. They can let you know if the problem is something that can be repaired, hopefully avoiding the need to replace the entire furnace prematurely due to failure. For more information, contact local professionals like Laroc Refrigeration-Metal Division.