If your furnace starts smelling weird, there is a good chance that your heating unit has developed some sort of problem that requires your immediate attention. Thankfully, the odor itself provides a clue about what may be wrong with it.
The only odor that is not a cause for concern is dust, as a dusty smell is common when a furnace is turned on for the first time after a long summer of inactivity. If the dusty odor persists beyond the season’s first few uses, however, it is still worthwhile to get your furnace inspected by a professional. More serious odors, and the problems that may cause them, are discussed in detail below.
Rotten Eggs Or Natural Gas Odors
If your furnace is emitting an odor reminiscent of rotten eggs or natural gas, the most likely cause is a natural gas leak. The substance is actually odorless, so utility companies commonly add an odor to it to allow customers to smell any potentially hazardous leak. Natural gas leaks can cause explosions and fires, so the problem should be addressed immediately. If you suspect a natural gas leak, open every window you have, get out of the house, and then call a professional HVAC repair service for an emergency appointment. If the house blows up, you want to be out of the blast radius.
Electrical Or Metallic Odors
These odors are generally caused by a malfunctioning part causing components of your heating system to overheat. For example, the blower motor’s bearings could seize up, causing the insulation of the wires to overheat. As the wires begin to melt, an electrical odor is produced. The blower motor is the most common culprit, but other parts could be at fault too. Loose relays, connections, or even a dirty air filter (due to restricted airflow) can produce the same problem.
If you experience an odor like this, do not try to diagnose the problem yourself. Instead, turn your furnace off and contact a professional HVAC contractor immediately. You should also monitor your heating system carefully while waiting for the contractor to arrive, just to make sure nothing happens in the interim.
A burning odor smells like an electrical odor on steroids. Overheating components are again the most likely cause, but this odor is often (though not always) accompanied by smoke as well. It is also possible for debris trapped in the duct work to produce this smell. Much like an electrical odor, you should shut your furnace down immediately and contact a professional if you smell a burning odor coming out of your furnace.
If you can smell oil, the most likely potential causes are an oil leak or a faulty oil burner. Leaks are preferable, as fixing them can be as simple as tightening a loose fitting. If you do not see a leak, there is probably an oil burner issue. These can have a multitude of root causes, so a professional should be brought in to diagnose your specific issue.
Heating System Tune-up
When your furnace starts producing an unusual odor, be sure to contact a reputable HVAC company right away. Sometimes these odors are attributed to something that can be dangerous. Make sure that you schedule a furnace tune-up to avoid costly repairs and breakdowns in the middle of the winter.
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