11/04/2022
FURNACE ODORS
Furnace odors range from a momentary and even nostalgic smell that are of little to no risk but can also be a warning of a very inconvenient and even dangerous situation.
If you encounter a strange unidentifiable smell from the furnace that continues after a couple heating cycles it is in your best interest to have your system diagnosed.
The following is a list and description of the most common furnace smells, what they could mean, and what should be done.
BURNING DUST
The most common furnace odor is burning dust and is typically not anything to worry about. This is going to occur after the heating system has sat dormant for months. When the furnaces is started after the summer months, the dust that has built up on your heat exchanger burns off creating a familiar odor that should dissipate after a heating cycle or two.
MUSTY/HUMID ODORS
It’s not rare for your furnace to give off a humid or musty smell at the beginning of each heating season. This is more common for system with air conditioning. The system may have a buildup of moisture from the A/C and it can cause a damp, musty odor. This smell should be eliminated after a few heating cycles to dry up the moisture.
STALE ODORS
A dirty furnace filter can create strange organic smells. As the furnace filter becomes increasingly soiled it is becoming contaminated by different organic odors found within your home. Aside from preventing the necessary airflow needed to properly circulate clean, filtered air thoughout the home, it is also allowing stale smells to linger longer.
CHEMICAL NOXIOUS ODORS
When you smell an uncommon chemical or noxious odor that you have not experienced from the heating system, it may be a sign of a cracked heat exchanger. This is a very serious issue that requires immediate attention.
A cracked or damaged heat exchanger has the potential to introduce dangerous carbon monoxide (CO) fumes into your home. Although sometimes accompanied by other odors, CO is odorless and very deadly. If you suspect this, immediately shut the heating system off and call an HVAC professional. We also always recommend having at least one CO detector on each level on your home.
ROTTEN EGG ODORS
This is commonly from natural gas. Natural gas, which is naturally odorless, has an additive to make it produce a strong rotten egg smell. It is not uncommon to get a small hint of natural gas each time your furnace starts but if this smell lingers for more than a few moments, shut the gas valve off and ventilate the area. Call your gas utility company to identify where the gas is coming from.
ACRIS METTALLIC/PLASTIC ODORS
Acrid metallic or plastic odors are usually an indication that electrical wiring or components are worn and overheating or have completely failed. Majority of the time, this smell is the protective coating on electrical wires or circuit boards burning off. This is another case where imminent danger could occur. If you believe you smell a metallic odor that could be related to electrical malfunction in your heating system, shut the furnace off at its circuit breaker and call a licensed mechanical contractor to diagnose and repair your system.