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All HVAC systems produce odors from time to time, but not all of them are cause for concern in your Columbia home. Learn how to identify problematic odors and handle them before they lead to big complications down the road.

Rotten Eggs

More often than not, when an HVAC system spreads a sulfuric odor reminiscent of rotten eggs throughout the house, this odor is actually the result of a natural gas leak. As most homeowners know, natural gas doesn’t have an odor, but all utility companies add a sulfuric substance to it to alert people about leaks.

Depending on where you use natural gas in your home, a leak could spring in different locations. If you use a natural gas furnace, for instance, a leak in that area can easily enter your home’s air circulation system and quickly make its way throughout your home.

Keep in mind that most HVAC systems include many components, and a rotten egg smell isn’t an indicator of overall system failure. Since it likely indicates a gas leak in or around your furnace, however, it’s something to take seriously. Instead of investigating further yourself, call your local utility company to report a leak right away. Follow the utility company’s instructions for keeping yourself and your family safe, since a gas leak can be harmful to your health.

Once you’ve alerted the utility company, it’s also best to call your local heating and cooling technicians and schedule an HVAC system checkup as soon as possible. Natural gas leaks are serious business, so leave this one to the professionals instead of doing extensive investigation or repairs on your own.


It may come as no surprise that an unpleasant sewage odor throughout your home can result from an actual sewage leak. Depending on the configuration of your HVAC system and the proximity of waste lines in your home, there’s a possibility that your HVAC system is located near a sewage line.

It’s important to note that the distinctive odor of sewage often comes from the production of methane and other gases. Like natural gas, inhaling these gases is dangerous, so it’s important to get to the bottom of the problem right away. Contact a plumber to find a solution for the sewer line, and call your local HVAC expert for advice on managing odors like this in your home.

When dealing with seriously offensive odors, most HVAC technicians will recommend changing the air filter to make sure that it’s not contributing to the smelly situation. Whether you’re dealing with major or minor odors, keeping the air filter clean and refreshed is always important. Dirty or clogged filters don’t just contribute to bad smells. They can lead to large-scale indoor air quality problems as well as slow down your HVAC system and cause it to run inefficiently.

Dirty Socks

The distinctive, unpleasant odor of dirty socks is familiar to HVAC professionals around the nation. You might encounter this smell in different situations, but it comes up most frequently when you’re transitioning from heating to cooling in the spring.

Essentially, the dirty sock smell results from mold and mildew buildup on the air conditioner’s evaporator coil. When you have the right environmental conditions and you’re not using the air conditioner for an extended period of time, mold and mildew can grow quickly. Turning on the air conditioner after a long rest period introduces these contaminants into your air supply, which doesn’t usually smell great.

The most straightforward way to deal with “dirty sock syndrome,” as it’s known, is by having the evaporator coil and other affected components cleaned and sterilized by an HVAC technician. Since air conditioners include so many surprisingly fragile parts, it’s always best to call in a pro to take care of this. Since dirty sock syndrome can happen around the same time every year, this is a smart time to schedule springtime maintenance and skip the odors next year.

Though dirty sock syndrome isn’t the worst as far as HVAC issues go, it can point to other issues that can lead to big problems down the road. For instance, excessive mold and mildew growth on your air conditioner’s evaporator coil points to a larger environmental problem that can return when you least expect it.

Instead of welcoming these contaminants into your HVAC system, stop them in their tracks by installing a germicidal UV lamp. This device works with the HVAC system to neutralize and kill bacteria, mold, and mildew, so you don’t have to worry about the smell or other health effects.

Dirty sock syndrome can also be an indicator that your HVAC system is oversized. When a system is too large for the home, it doesn’t operate efficiently and instead tends to short cycle, or undergo frequent cooling cycles that are shorter than normal. Over time, short cycles can lead to excessive condensate buildup in the air conditioner, setting the stage for mold, mildew, and other indoor air pollutants. When deciding on a new system, work with your HVAC professional to ensure that it’s sized accurately from the start. If your system is older, consider upgrading to a correctly sized and great smelling HVAC system.


A stale or musty smell throughout your home often indicates that the air conditioner’s condensate drain isn’t working properly. When the drain clogs, it produces excess moisture that can cause mold and mildew to grow. If the conditions are right, mold and mildew can also grow on the air conditioner’s condenser coil or even in the system’s ductwork. Once the mold spreads to the air conditioning system and ductwork, it can easily circulate through your house and distribute mold spores throughout the house.

Since air conditioners are complex devices, call in an air conditioner tech to do maintenance like cleaning the condenser coil, emptying the drain pan, and emptying the drainage line. While these are some of the most common maintenance tasks, an experienced tech will know when the situation demands additional steps. For instance, if the tech suspects that the mold issue includes the ductwork, he or she can complete a thorough check and remediation if necessary.

If you don’t already have one, this is a good time to consider incorporating a whole-home dehumidifier into your HVAC system. This unit can help keep humidity under control throughout your home, so you don’t have to worry about mold growth or mustiness elsewhere.


If you smell smoke in your home, first try to determine what kind of smoke you’re inhaling. Recirculated cigarette or tobacco smoke, for instance, isn’t the sign of a major HVAC problem, but it can be a nuisance and a health concern. If you’re dealing with excessive tobacco smoke in your home, consider upgrading your air filter or installing an air purification system. Most standard filters can’t capture microscopic tobacco particles, but some high-end filters can, especially those that work with air cleaning systems.

If the smoke has less of a tobacco scent and more of a burning odor, try to get a better impression of where it’s coming from. If you think it’s coming from the HVAC system, it’s better to be safe than sorry even if you don’t see an active fire. Turn off the HVAC to avoid additional damage and call your HVAC technician for an immediate service call.

An HVAC expert can advise whether you have a major problem or a minor oil leak on your hands. If you rely on an oil furnace to heat your home, an oil leak can easily develop a burning smell that quickly circulates through your home. Since the origin of the problem isn’t always easy to diagnose, it’s best to leave it to an experienced heating and cooling technician.

If you’ve purchased a service agreement with your local HVAC pros, this is one of the many times you’ll thank yourself for making such a good decision. HVAC companies can get backed up with service calls during busy seasons, but having a service agreement often pushes you to the beginning of the line and drastically reduces wait times.

Do any of these odors sound familiar? Call Griffith Energy Services, Inc. to consult with the HVAC experts in the Columbia, Maryland area: 888-474-3391.

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