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Stop Furnace Odor

Your central heating system is great for maintaining comfort and health, but since the blower fan circulates warm air throughout your home, a single foul smell in the system will reach every corner of your home-life. Fortunately, when there’s a bad smell you already know that a problem exists and you can take care of it immediately. It’s important to know which smells are dangerous (and require a professional) and which are simply annoyances that need to be cleaned up.

What’s That Smell?

When you turn on the furnace, or the fan starts blowing, and you breath in what should be clean and refreshing air but choke instead, what does it smell like?

Dangerous Smells:

If you smell burning or a heavy dusty-odor, then the first thing you should do is check on your furnace. Make sure that nothing is actually on fire. If you’re smoke alarms are in good-working order, then you’ve nothing to really worry about, but it’s best to check first hand. The acrid, dusty scent is usually common when you turn on the heater for the first time, but if you’ve been gone for a vacation, or let your air filter for too long without replacing it, you can get similar odors. Cleaning the air filter is the best way to try and clear the air. If that, and time, doesn’t fix the problem, call a service technician.

Rotten eggs might be the cause of foul odor in your ventilation system, but it’s unlikely. This odor is added to natural gas because gas is odorless. If you smell rotten eggs coming from your vent, it’s likely that there’s a gas leak. Evacuate your home, shut off the gas at the tank (outside), and call a technician at once. The same goes for smelling any kind of fuel, like oil.

As for any electrical smells or the scent of overheating metals, there’s a chance your furnace is getting too hot, or airflow has become so restricted that ventilation isn’t moving heat quickly enough to prevent overheating. A metallic or burning-plastic scent should direct you to immediately turn off your furnace and contact an HVAC technician, especially if there’s even a hint of smoke to it.

Foul Odors:

Most truly foul odors are not caused by your furnace system, which is fortunate because it often means you can fix it inexpensively. Some are simple, as with the musty odors we mentioned previously. And many can be fixed simply by cleaning out your air ducts. But all remedies require you to find what’s causing the odor first. Without knowing the source, you can use as many air fresheners as you want without success.

Unfortunately, one of the most common sources for bad odors is also the most unwelcome. Small animals (rodents or birds for example) seek refuge in attics and ventilation systems if they’re able to get in. When this happens, you end up with the scent of dead animal, running throughout your home. Removing the remains is the first step. Clean out that section of air duct and air out your house if at all possible.

NOTE: You can speed up the deodorizing process by using vinegar to dampen a rag and waving it through the air. It sounds silly but it works!

Pet smells from excess hair, urine, and waste can also be a problem. If you get a strong whiff of pet urine whenever the furnace is running, you should check any floor level ventilation registers. The scent can be picked up if it’s close enough to a vent. Clean up the mess and the problem is solved.

If you smell sewage or waste water from your vents, there may be a broken black-water line or an open sewer line near an intake that your furnace uses. A quick check of your furnace or any external vents can help determine if that’s the problem. If it is, then it’s time to call a plumber to seal off the sewer line.


Don’t hesitate to give your Comfort Heroes a call at (217) 866-1596.

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