Furnace Warning Signs: What They Are And How To Identify Them

You can, usually, tell if your furnace is functioning at optimum or not through simple observation, or professional furnace inspection. By checking your furnace’s filters, vents and other part’s condition, you can identify furnace warning signs that indicate your furnace is functioning less efficiently. HVAC professionals can, of course, detect more technical problems, during the inspection of the furnace.

Warning signs of a faulty furnace

Funny odors

Funny odors, emitted by your furnace, are a sign that one or more parts of the furnace are not in proper shape and are, therefore, not functioning properly. Such odors could emanate from dirt on dirty or clogged filters, obstructed airflow, gritting metallic parts, and or burning furnace parts. Simple nut adjustments or cleaning/ unclogging of filters and vents can rectify the problems. In other instances, only professional HVAC attendants can detect the real problem and rectify it.

Unstable thermostat readings

Your furnace’s thermostat regulates the degree at which your furnace can heat your indoor air. Absence of change in indoor air temperature whereas the reading on the thermostats has changed, or overheating of indoor air when thermostat readings remain constant, is a sign that your furnace or thermostat is broken. Check your filters, vents and other parts for dirt or obstructions that may be the cause of your furnace malfunction. You can also check your thermostat setting and location to ensure it does not detect heat or cold from other appliances.

Abnormal noises

Before you identify what noises are abnormal with your furnace, you need to know what normal noises your furnace emits, if any. For instance wood furnaces emit crackling sound as the wood burns and occasional sparks, whereas burning gas has a distinct pressure sound. A soft humming or fanning sound may be the only sounds an electric furnace emits from rotating fans or mortar. Any other sounds from your furnace signify something that needs to be fixed.


Obstructed airways, worn out, and dirty furnace parts can inhibit efficient functioning of any furnace. You may sense when your furnace functions less-efficiently from abnormal sounds, odors, flames or sparks, as well as imbalanced indoor air temperature. For all your HVAC needs, including furnace maintenance and repairs, contact your local HVAC contractors.