The primary function of your HVAC system is to control the temperature and airflow in your home, not generate odors. While most of the time, you are unlikely to be aware of any smells, occasionally, you may notice a foul smell in the air coming out of the vents. Certain odors are harmless and temporary, but others can be lingering or a sign of a serious HVAC issue. So, what is the cause of that foul odor and is a cause for concern?
A Smell of Smoke:
If there is a sudden smell of smoke that is emanating from your vents, it is a bad sign in almost every scenario. It is usually caused by an electrical or mechanical problem within the HVAC system. There are many moving parts within the system such as fans and motors that carry the potential for overheating or even catching fire if your system has not been properly maintained.
If something smells like burning and the odor appears to be coming through the vents, immediately shut off your HVAC system using the thermostat and check your outdoor air conditioning unit. If you can see smoke being emitted from the condenser, call in a repair professional and ensure the system stays off.
The Other Type of Smoke:
If someone is smoking tobacco inside your home, it is likely that the smell will be circulated through the HVAC system including the vents. A stale smoke odor can even become attached to your condenser coils, leaving a film of odor inside your ducts. This may be difficult to detect if you have a smoker living in the home, so it is more commonly an issue if a nonsmoking family buys a home from someone with a smoker in their household.
Fortunately, this problem can be resolved by a professional HVAC technician. The technician will use special cleaning methods to ensure the ductwork is cleaned to control any odors. While deodorizing smelly coils can be more challenging, a thorough cleaning can make a massive difference.
Musty Smells:
If there is a musty or mildew smell coming out of your vents, it is a sure sign that you have a damp problem inside the ductwork. The coils and ductwork of an HVAC system provide the ideal conditions for mold and mildew to develop, and when it is left unchecked, it can easily spread to other areas of the home. The underlying causes for musty smells include insufficient insulation, leaking ductwork or blocked drainage tubes. Unfortunately, dealing with mold and mildew can be hazardous; the spores can easily spread and are toxic when inhaled. You will need to determine and correct the underlying problem before the mold or mildew can be cleaned up. This is usually a job reserved for the professionals, as they have specialist equipment and protective gear to avoid spores being carried any further throughout your home.
While it is usual to smell an odor when you first fire up your furnace after the summer, this is normally a temporary smell. It is caused by dust and debris that has settled on the heating being burnt. This should dissipate quickly, especially if you have opened some windows, but other smells should not be ignored. A bad smell can be an indication of a problem, and you should have it checked by an experienced HVAC technician as soon as possible.