My Air Conditioner Smells Bad!

You arrive home after spending time outside on a hot and humid day. All you want is to relax in comfort with the air conditioner blowing cool refreshing air around you. The last thing you expect or want is a putrid smell assaulting your senses when you turn on the AC. “Why does the air conditioner smell bad?" you desperately ask yourself. Shortly followed by "What did I do to deserve a smelly air conditioner?”

There are various reasons why your air conditioner could be blowing foul-smelling air to your living space. Determining what kind of unpleasant smell your AC is producing can help you identify the cause so you can resolve it quickly.

Our sense of smell and what it perceives in the surroundings are critical to healthy living. Medical experts say that what our olfactory organs detect from the air can impact our metabolism, nutrition, moods, and even our day-to-day safety. It is essential to maintain an environment free from bad odors whether natural or chemical.

The way air conditioners are designed to circulate air should reduce the risk of spreading a bad smell from one source point to the entire house. So if your air conditioner smells, exercise caution when investigating the source of the bad odor and do not be hasty to try to solve it on your own without the proper equipment and gear. Burning smells or gaseous odors are especially hazardous to health. It is always best to seek professional help from a trusted technician in dealing with an odd-smelling air conditioning system.

An air conditioner could be your best friend and your worst enemy at the same time when it comes to indoor air quality. Its process of cooling works best in airtight spaces because it recycles the same air in your home over and over until it is cooled to the temperature on your thermostat.

Yes, you read it right: The air conditioner recycles the same air within your house. No, it does not bring fresh air from outside.

Why does the air conditioner smell bad

If you do not know it already, all AC units function the same way, regardless of what brand it is. It draws in the warm moist air from your indoor space and circulates it inside its mechanisms. With the help of the cooling gas-liquid refrigerant, the heat and excess humidity are separated from the sucked-in air. The removed heat is expelled outside, while the now chilled air is blown back inside the house.

This is good news for you because no matter what the temperature and level of humidity are outdoors, your AC will maintain your preferred temperature dictated through your thermostat. As long as the windows and doors are closed and gaps are sealed, air conditioning can also reduce your exposure to outdoor pollution and allergens that could be dangerous to some.

The bad news is when a foul smell from whatever source mixes in with the indoor air, the AC will not discriminate and will circulate the odor around the house. Unless the odor is  caused by big enough particles that the AC can filter and trap, the stink which is carried by tiny molecules can roam freely around your breathing space.

How quick and skillfully you deal with the source of the bad smell will determine how safe and healthy your family’s breathing air is going to be.

What the Odor From Air Conditioners Can Tell You

Among our five senses, our sense of smell could be the most mysterious according to science experts. Dr. Gary Beauchamp of Monell Chemical Senses Center in Philadelphia, who focuses his studies to taste and smell, was interviewed by News in Health (NIH), an online newsletter from the National Institutes of Health. He shared that there is an estimated number of 10,000 to 100 billion odors that a human can smell. 

We have a limited number of odor receptors while there are countless minuscule molecules in the air that we breathe. But the vast diversity of what we can smell is because a single minute molecule can stimulate “specialized sensory cells” within the nose which then activate a mixture of odor receptors, “creating a unique representation in the brain of a particular smell,” NIH printed.

What makes our olfactory sense more amazing is that odor could be relative, which means that two individuals can both smell the same thing but how they perceive it may vary. One person may smell it as unpleasant and detest it, while another person can tolerate it and even like the smell.

One thing is definite though and one fact that the medical world unanimously agrees upon: What we smell can impact our well-being. When it comes to HVAC equipment malfunctioning it could even save your life!

The New York State Department of Health website warns that “Exposure to odors could result in health effects ranging from none, to mild discomfort, to more serious symptoms. Some chemicals with strong odors may cause eye, nose, throat, or lung irritation. Strong odors may cause some people to feel a burning sensation that leads to coughing, wheezing, or other breathing problems.”

If the source of the stench was not eliminated, prolonged or recurring exposure to the bad smell can even affect your emotional health. “It also could affect mood, anxiety, and stress level," the health site warned.

You will be relieved to know that health symptoms from foul smell exposures typically quickly subsides when the odors stop. The key is to detect the source and to remove it.

But how will you know what is causing the stench? Your only clue is that the odor spreads rapidly as soon as you turn the AC on. To help you with your detective work, here is a rundown of the common smelly problems associated with your AC. 

AC Smells Like “Dirty Socks”

This type of bad odor is pretty literal and easy to identify. If the air circulating inside your house when the AC is on is similar to a sweaty gymnasium, with filthy unwashed clothes spread all around, you have the notorious “dirty sock syndrome.” Coined in the 1970s, this term has become very well-known in the HVAC industry which gives you the idea of how often it occurs in American households.

ABC News published the results of the study from the University of Oregon that 12% of bacteria were able to reproduce in the dark versus the 6.8% of bacteria that survive in a well-lit area. Hence, the dark space inside the compact coils of an AC is an ideal breeding ground for bacterial growth.

If left unattended for too long, mold growth can also decrease the performance of the unit over time and leads to a shorter lifespan of even an expensive AC model.

Check the pipes around the house for water leaks or if the drainage needs upgrading. Clean or replace your filters if necessary. Cover any exposed soil in the basement. Consider installing a whole-house dehumidifier if moisture problems persist.

AC Smells Like Exhaust Fumes

Since we are not in medieval times anymore where people use gas in almost every mechanism, we are typically alarmed when modern and expensive equipment like your AC suddenly smells like exhaust fumes or gas.

There is also the risk of Microbial Volatile Organic Compounds” (MVOCs) mixing in with the air your family breathes. MVOCs can be the source of allergic reactions, asthma, and neurological complications.

Burning Smells From AC

What makes the burning smell more distinct is that when you smell something is on fire, it is almost certain that something is. This type of bad odor problem should never be ignored and must be dealt with quickly.

The Rotten Egg Smell

The rotten egg smell is exactly what it sounds like - blech! Although some who have knowledge of chemicals also identify it as hydrogen sulfide (H2S) gas.

The Bottom Line: Bad Smells From Air Conditioning Equipment Are More Than Just Stinky!

An air conditioner can produce a variety of unpleasant smells. These are more than just a nuisance but can let you know if there is a minor or even major issue with your air conditioning system. We wish we could say there is an easy DIY fix when your air conditioner smells bad. However, when working properly an AC should not produce or spread any odors; it more than likely is a sign of a serious problem.

Due to the electronic components, refrigerant gas, and connection to gas heating systems, if you are experiencing persistent bad smells from your air conditioner contact an HVAC contractor.

Excessive humidity is one of the greatest enemies of home comfort. Imagine going home after a tiring day at work on a hot summer afternoon. You are looking forward to putting your feet up in your cool cozy living room but instead are greeted by the sweaty, muggy atmosphere as soon as you enter the door.

So while having a lower indoor temperature is important, reducing excess moisture from the air is equally essential to have a comfortable indoor environment. Lower levels of humidity also decrease the chance of mold in your home which is notorious for triggering allergies. So should you run a dehumidifier and air conditioner at the same time?

Having both home devices work together and at the same time will provide the most favorable home environment for you and your family. The correct kind of dehumidifier has the potential to work with an air conditioner to provide more comfort for most homes, it cannot replace an air conditioner with regards to lowering the temperature.

Many turn to air conditioners for cooler air, yet many others use dehumidifiers to solve the relative humidity problem. 

should you run a dehumidifier and air conditioner at the same time

If you are after the optimum comfort for yourselves and your family, you might wonder now whether you can run a dehumidifier and an air conditioner simultaneously. Will it cost more to run two home devices simultaneously? Can you have just one without the other? 

Before we dive into these questions, let’s look at first how an air conditioner and a dehumidifier work and see if there is any overlap with their functions nor can either home appliance interfere or contribute to the other’s job.

How Does an Air Conditioner Work?

From the term itself, an air conditioner “conditions” or processes the air to the desired temperature set through the thermostat, a small device attached to an indoor wall. Once you determine your preferred level of temperature, the thermostat will send a signal to the air conditioner to initiate its cooling process to lower the temperature.

Contrary to what many people think air conditioners do, the AC does not put cool air in the room, it removes the heat from the same air it has pulled in. 

The cooling process starts with the air conditioner blower drawing in the warm air from your living spaces and circulating it through the evaporator and the ductwork. The condenser and the compressor, normally situated outside the house, pumps the splendid chemical compound called the refrigerant. This liquid-gas substance absorbs the heat from the air as it passes the evaporator. 

Once the air is chilled, it is released and distributed through the ducts. This process repeats itself several times until the desired level of temperature is reached.

What happened to the heat removed from your indoor air? It is continually expelled outdoors. 

The comfortably cool air indoors despite the blazing heat outside is the best part of having an air conditioner. Some modern HVAC designs also integrated heating functions into ACs so they can serve as heat pumps during the winter with minimal energy consumption than conventional heating systems.

How about a dehumidifier? How does it contribute to the general indoor air quality of your home?

How Does a Dehumidifier Reduce Excess Moisture?

The process by which a regular dehumidifier eliminates the excess humidity from your home is very similar to an air conditioner. 

The dehumidifier draws in the humid air from your home, circulates it over coils with refrigerant running through them, and releases the air back into the room with lesser moisture and considerably lower temperature. Meanwhile, the water collected from the moist air is contained in a bucket underneath.

Some modern dehumidifier designs take a different approach by using a desiccant, a water-absorbent material attached to a wheel. When the warm, humid air passes through the desiccant wheel, the moisture is removed from the air and collected in a tank. The noticeably cooler air is now produced by the dehumidifier.

Wait. If a dehumidifier takes away the humidity and also cools the air, isn’t that the same as what air conditioners do but likely at a lesser cost? Not exactly.

Air Conditioners Remove Humidity from Indoor Air Through Cooling

Dehumidifiers and air conditioners may appear to operate in the same way on the surface. But a closer view of how AC lowers the temperature may convince you that it is still the boss of the home comfort.

Air conditioning systems' main job is to lower the indoor temperature to whatever level you desire and no matter how high the actual temperature in the space is. The AC’s cooling prowess is so superior that despite the smoldering 100 degrees Fahrenheit heat outdoors, your home can still manage to feel like it’s around 75 to 80 degrees cold.

Besides the capability of lowering the temperature to at least 20 degrees, another great thing about air conditioners is how it impacts the overall humidity inside your home. A happy coincidence is as your AC lowers the indoor temperature by extracting the heat, it also reduces the moisture from the air in the process.

So while cooling is AC’s primary function, getting rid of the humidity from the air is its side job.

A Dehumidifier Increases Air Conditioner Efficiency

So if an air conditioning unit seems to have it all–cooling and managing the humidity–why would you still consider running a dehumidifier?

The simple answer to why you should run them together is that the combined dehumidification processes of the air conditioner and a dehumidifier will give you the most ideal cool and dry environment. This is especially true if you live in areas like Texas, Florida, or Louisiana where it can be extremely hot and humid.

While you can trust that the AC will do its task of chilling the air and moderately removing the humidity, a dehumidifier can add to your air conditioner efficiency as its sole focus is eliminating a significant amount of moisture from the air. It eases the pressure from the cooling unit to perform two duties at the same time.

Dehumidifiers are also extremely useful when you reside in areas where there is less need for cooling but the humidity is very high. These places include Boston, San Francisco, and Alaska where you would not dare use air conditioning but there is a great demand for reducing humidity.

Can I Run a Dehumidifier Instead of an Air Conditioner?

The crucial question still remains: Can you just use a dehumidifier and do away with your air conditioner?

Many homeowners want to learn a definite answer to this obviously to economize on their home comfort. To be fair, the upfront price of an air conditioner unit and its installation is remarkably higher than most home appliances, ranging from $3,000 to $8,000. Not to mention, the operational and potential repair costs can be quite costly, too.

Meanwhile, a dehumidifier costs strikingly less to purchase and install than an air conditioner, averaging from $800 to $2,000. It also needs a lesser amount of electricity to run. 

While a dehumidifier does not necessarily remove or filter mold like air purifiers, running a dehumidifier in especially high humidity areas in the house helps prevent mold and mildew growth. Mold spores are one of the most common causes of allergies in the US. 

However, keep in mind that no matter how reliable a dehumidifier is in terms of eliminating impressive amounts of humidity, it cannot compete with the cooling power of an air conditioner.

All in all, the best response to the debate, “Can I run a dehumidifier instead of an air conditioner?” It depends.

There are at least three factors to consider: where you live, what is your budget, and what are your ideal conditions for comfort.

Your place of residence will dictate whether you require air conditioning or dehumidifying. Hot and humid locations would demand the use of an air conditioner, while areas that are not necessarily hot but have extremely high humidity would benefit more from a dehumidifier.

Your budget dedicated to fighting humidity and controlling temperature in your house also play a huge role in deciding which device to keep. As mentioned, the overall cost of running an air conditioner is more expensive than having to buy and only run a dehumidifier. 

Finally, your preference in terms of home comfort will influence your choice between an air conditioner or a dehumidifier. If you like your house cool and comfy, you will likely favor an air conditioner. If high levels of humidity bothers you a lot but not as much if your space is cold, then the dehumidifier is for you.


In view of the points presented above, both the air conditioner and the dehumidifier have their share in promoting comfort inside the house. 

An air conditioner concentrates on lowering the temperature and lessens the humidity as a consequence. While running the dehumidifier will help the AC eradicate excessive moisture from your house.

Air conditioners are a staple in any American home nowadays. It comes as no surprise then that people think more about how this modern device impacts their family’s health. 

This concern is not out of place because many medical experts are looking into the relationship between the increase in blood pressure and the use of air conditioners. Does Air Conditioning Raise Blood Pressure? What are the findings and how does it relate to you and your household? Let’s find out.

What Can Cause High Blood Pressure?

One of the most common health issues in America is hypertension. One in every three Americans is diagnosed to have high blood pressure, with people over 50 years of age being 30% to 50% more susceptible to suffering from it. Hypertension is the gateway to other several heart and brain diseases, including heart attack and stroke.

Does Air Conditioning Raise Blood Pressure

From the term itself, blood pressure refers to the amount of force your blood pushes against the wall of your arteries. Meanwhile, arteries are responsible for transporting blood from your heart to every part of your body. 

The danger begins when there is an increase in the pressure of blood’s movement through the arteries. If too much force is applied to these blood vessels for an extended period, the artery can become elastic reducing its capacity to carry blood throughout the body.

For a health problem that is contributing to more than half a million fatalities in the US, high blood pressure comes with almost no distinct symptoms. Often called a “silent killer,” a person with high blood pressure can walk around without knowing he has it. Constantly measuring your blood pressure levels is the only definitive way to determine if you have hypertension.

Medical experts point to natural causes of high blood pressure such as old age, the patient’s family history, race or ethnic group, long-term conditions such as diabetes, high cholesterol, kidney illnesses, and hormonal imbalance.

But many lifestyle choices also surge the chances of high blood pressure including tobacco use, obesity, stress, high cholesterol, salty, and fatty diet. 

However, the latest scientific findings linked air conditioning and the overall indoor air temperature to potentially impacting blood pressure levels. Is there any truth to it?

How Can Air Conditioning Affect Blood Pressure?

There are always two sides to the story when it comes to the impact of AC on our personal and our family’s health. 

On one hand, air conditioners have been found to have immense health benefits, especially against heat-related illnesses such as heat stroke and cardiac arrest. Hospitalized patients with respiratory diseases noticeably recover faster if placed in air-conditioned rooms. Several studies have also proven that mortality rates related to excessive heat and extreme levels of humidity have significantly reduced because of the use of AC.

On the other hand, many assign blame to air conditioning for some health problems such as constant fatigue, or what some refer to as “sick building syndrome,” dry skin and nasal passages, and breathing problems.

A recent study by the University College London (UCL), a prime public research university in the United Kingdom, revealed a new AC health risk to add to the list above. According to the said reputable research institution, experiments published in the Journal of Hypertension showed that “lower indoor temperatures were associated with higher blood pressure.”

Can Air Conditioners Really Increase Blood Pressure Levels?

The question remains whether air conditioning can cause high blood pressure. 

UCL’s newfound study mentioned earlier discussed that maintaining a warmer indoor air temperature is more beneficial in keeping blood pressure levels normal. This is of course in the company of keeping a good healthy diet and wholesome changes in a person’s lifestyle.

How did the proponents of the research determine how variations in indoor temperature affect blood pressure? After identifying 4,659 participants of the experiment and their overall health and current lifestyle, researchers had nurses visit the participants in their residences and measure their BP and the indoor temperature of their homes.

The scientists and scholars discovered from the figures that those who lived in houses with very low temperatures have an average systolic BP of 126.64 mmHg and average diastolic BP of 74.52 mmHg. When they compared it to participants with warmer homes, they observed an average of 121.12 mmHg (systolic) and 70.51 mmHg (diastolic).

Based on these sets of information, the researchers concluded that “every 1°C decrease in indoor temperature was associated with rises of 0.48 mmHg in systolic blood pressure and 0.45 mmHg in diastolic blood pressure.”

The disparity between these data is significant enough to publish the study and make recommendations about the use of air conditioning in the UK and in American homes as well.

AC Cuts Heat-Related Deaths

Heat-related deaths are a real and serious cause for concern., a website dedicated to being a "one-stop resource for medical news, clinical reference, and education" reported that there are about 400 deaths every year in the United States attributed to extreme natural heat. 

This staggering number of mortality cases because of the punishing heat is surely upsetting. However, more of these instances could be prevented from multiplying.

The Washington Post, in the Science and Health section, published the results of a study entitled, Adapting to Climate Change: The Remarkable Decline in the U.S. Temperature-Mortality Relationship over the 20th Century (2015, May). This research attributed the decline of heat-related deaths in the country to the prevalent use of air conditioners in private homes and offices.

The publication also presented related findings on how the innovation of air conditioning saved the lives of people who could have died in extremely hot weather conditions.

  1. After 1960, there was a noticeable drop in mortality due to extremely hot weather temperature that exceeds 80° F by about 75%. There were 20,000 fewer deaths per year because Americans found advanced ways through technology to protect themselves in very hot, humid climates.
  2. Air conditioning is one of the celebrated health-related developments that improved the well-being of US residents. The other two are residential electricity and access to health care.

    Enabling electricity to be accessed by homeowners countrywide allowed them to use fans, refrigeration, and ultimately, air conditioners. While better access to health care combined with the installation of AC in hospitals make the thermoregulation, or balanced core internal temperature of recovering patients, trouble-free.
  1. Since AC has been introduced in the market in 1960, the current value of consumer surplus in the United States ranges from $85 to $188 billion ($2012).  Consumer surplus is the difference between the price that buyers of a product pay and the price that they are willing to pay.

    As an example, a consumer is willing to pay $700 for an AC unit but got it for only $500. This $200 that he did not have to pay represents the additional satisfaction a buyer gets when they are paying a lower amount than what they were willing to spend.

    This substantial amount of consumer surplus for AC means how people find AC to be very helpful and almost a necessity in their daily lives.

Other recognized published studies support the fact of the diminishing effect of AC use to mortality due to extreme heat.

Your Air Conditioner and Your Health

While the UCL research did not propose strict rules about not using AC, it did make a recommendation of keeping indoor air temperature to at least 70°F (or 21°C).

Additionally, the temperature influenced by air conditioning is not the sole factor that leads to hypertension. The study also points to lack of adequate physical exercise and social deprivation as contributing elements to increased blood pressure.


We can all agree that air conditioning does us a lot of good in terms of comfort and healthy living. But as with everything else, moderation is the key.

Before you decide whether to purchase a new single stage or a two-stage air conditioner for your home, you have to know some key information about each product and how it can benefit you and your family. Most sources will give you almost the same answer which of the two is the best, but you might be surprised by what they don't tell you. 

DP single vs two stage air conditioner

The most basic difference between the single stage vs two stage air conditioner is the type and speed of the compressor. The compressor is the heart of an air conditioner and is used to circulate the refrigerant in the system under pressure.

While the compressor does all the heavy work, the properties of the refrigerant is what produces the cooling effect in the air. Single-stage works at one level only: 100% capacity or High, while the two-stage AC operates on two levels: Low or 60% to 80% (depending on manufacturer) of the maximum, and High or 100%.

One Stage Air ConditionerTwo Stage Air Conditioner
Compressor has one level of operation: HIGHCompressor motor has two levels of operation: LOW & HIGH
Cools your home at 100% capacityRuns at a lower speed and takes longer to cool
Price: $2500-$3500Price $4000-$5000
Repair cost: LowRepair Cost: Moderate to High
Basic and easy-to-find parts for repairs and could be performed by most HVAC techniciansComplex technology with harder-to-find components. Few technicians are trained to fix and maintain
Less prone to breakdown and mechanical problems due to simplicityMechanical problems more likely due to complexity
15-25 year lifespan7-12 year lifespan

It’s important to understand how single stage and two stage air conditioners differ before deciding which type is appropriate for your circumstances. Many people may be buying an air conditioner for the first time - but once you’ve had a bit of experience purchasing units you might not want to be enticed by promotional offers that aren't really going to get your home more comfortable.

Imagine that you've just moved into a new home. You're probably not thinking about how long your appliances will presumably last in your house - but appliances like an air conditioner tend to stay with you for years. You want to make the right choice.

If you’ve had an old air conditioner and it recently broke down, you may be thinking about purchasing another one of the same type that you already have. You might do this because it lasted a long time, or because your current AC was adequate and you were happy with its performance.

On the other hand, if your previous air conditioner broke down sooner than expected, you may want to explore air conditioning options that weren’t available when you last bought one.

Whichever your situation is, you are making the right move by doing research first. Be careful though: Most websites or so-called AC "experts" will merely advise you to purchase a more expensive unit which in this case is a dual-stage air conditioner. It is still up to you to make the decision based on your individual needs and more importantly, your budget. 

Let's start diving into the three most vital factors to consider when purchasing either a single-stage or two-stage air conditioner.

Factors to Consider When Choosing Performance Air Conditioners

Cool and Comfort

A Single Stage air conditioning unit is cooling your home at one capacity: high. This is perfect if you want to quickly get to your desired temperature level as soon as possible, perhaps on a really hot and humid summer day when you walk into your house. It will stay on until it reaches your thermostat setting, and then cycle off automatically only to turn back on once the ambient temperature gets warmer again.

Two-stage air conditioners are considered performance air conditioners and work differently. A two-stage air conditioner's compressor starts in the Low setting, which is equivalent to 60% to 70% of its maximum. This setting suits for milder weather days when you don't need as much cooling. Most of its running time, the setting is on Low so it runs longer and reduces the starts and stops of the unit.

Once it gets too hot outside, this unit will crank up to High, equal to the 100% capacity of a single-stage air-conditioner. It will stay that way until the thermostat in the room is satisfied.

Affordable Pricing

A single-stage air conditioner is significantly more affordable than the two-stage air conditioner. The two-stage air conditioner is more state-of-the-art and complex so the upfront price, labor cost and additional installation charges are significantly higher than the single-stage AC unit.

A single-stage air conditioner in the mid-efficiency range can cost $2,500 to $3,500 including installation, while high-efficiency models can cost $4,000 plus for the hvac equipment and installation costs.

On the other hand, in its mid-level efficiency, a two-stage air conditioner costs between $4,000 to $5,000. While the high-efficiency two-stage units can cost you between $5,000 to $7,000 to purchase the unit and have it installed, not yet including the needed add-ons such as a variable-speed air handler or furnace.

Potential costs such as repair and maintenance of a single-stage and a two-stage air conditioner are also very different. Because of its more complex design, two-stage AC naturally has a larger number of parts and they are not always easy to find in stock. Obviously, the labor cost for repair for the two-stage unit also is higher compared to single-stage.

HVAC Energy Consumption

Since a single-stage air conditioner cools your home at a full blast, it can do the job of chilling your home quickly and will automatically turn off once it reached the thermostat setting. This could mean that there is a considerable amount of energy consumed in starting up and turning off the furnace during the day.

The two-stage air conditioner, however, will consume lesser energy since it takes longer to run and there are fewer times for it to turn on and off.

What most sources will not tell you is that two-stage cooling is not ideal for every home, specifically for larger residences, unless you have a zone system which further complicates the HVAC system.

A house with this kind of system makes it easier to control the temperature in each zone or room individually. Without this, stage one of the two-stage AC blower speed will most likely be insufficient to push the cool air to all places in your home. Unless you're willing to purchase more than one two-stage unit for example, which by the way, is undoubtedly more expensive!

Why Single Stage Is Better Than Two-Stage Air Conditioners

Most homeowners decide to purchase a single-stage air conditioner because it is more practical for their needs. The number one reason is that the up-front cost is lower.

The second factor most people consider whether to choose a single-stage air conditioner over two-stage AC is the size of their home. A smaller to an average residence can effectively be cooled by just a single compressor. It's worked well for 50 years. If it ain't broke, don't fix it. You're just trying to cool your air.

Lastly, but not the least reason why single-stage is more reasonable, is the potential cost of repair and maintenance. A single-stage air conditioner's ease and low cost of repair is a huge advantage.

More complicated equipment such as a two-stage air conditioning unit will definitely have more expensive parts. And these HVAC parts are not always easy to find at local distributors.

Getting them delivered from bigger out-of-town branches may take time and additional courier charges. Let's face it, one of the last things you want to hear when it's blazing out and your AC is down is you have to wait for parts. This rarely happens with a one-stage AC.

Accompanying this problem is looking for a trained technician to fix the two-stage air conditioner. Since it is more high-tech than your regular AC, only a few expert mechanics can understand and repair its issues. And since he may be one-of-a-kind in your area, you may be charged more than your average repairman.

What about the Variable-Speed Air Conditioner?

If you are looking to buy an even more lavish and high-tech air conditioning unit than the two-stage air conditioners, you may want to consider variable-speed air conditioners. Why is it pricier? While the two-stage air conditioner runs on Low at 60% to 70% of the maximum power, variable speed can run at much less capacity: 25% to 30%. This results in longer cycles that can almost last a whole day during the summer season. 

One advantage of this variable-speed air conditioner is it promises better dehumidification of the air in your home. It claims  greater comfort at a lower utility cost.

Any drawback? The amount of needed air conditioning repair of course. And since it is an upgrade to an already expensive two-stage unit, an average variable speed air conditioner ranges from $6,000 to a whopping $10,000.

Single Stage vs Two Stage Conclusion

Don't get sucked in to all the marketing. When the weather turns warm and you're in need for a new HVAC system, don't focus too much on heating and air options. Your main decision is to choose the right contractor. Nothing is more important on the installation of a new HVAC system.

A good contractor will determine the cooling needs of your home and help you find the right type of AC that will cool your air perfectly. And the right AC will probably be the less expensive option.

Take that extra money for a two stage AC and buy a better thermostat or air filter or when you get a new system. Those can improve indoor air quality and you'll be much happier with that kind of upgrade.

You will be happy with any single stage model as long a quality contractor handles the installation. And they won't recommend features that you don't need.

Carbon monoxide poisoning is a serious threat to your family's health. You desperately want to eliminate any chance of being harmed by this hazardous gas. You know that your gas furnace poses the risk of CO, but do air conditioners produce carbon monoxide?

Common residential air conditioners do not produce carbon monoxide. Combustion is not part of the cooling process so it cannot produce carbon monoxide as a byproduct. In fact, air conditioning season tends to reduces the chance of CO poisoning because most fuel-burning appliances are off.

That being said, there was a time when some air conditioners used natural gas to produce cooling. But that was a long time ago and it would be shocking to see a system like that still in use. There are also some very, very rare cases of units in industrial settings that could produce CO. We'll touch briefly on this type of air conditioning equipment later in this article.

DP do air conditioners produce carbon monoxide

But there is one danger that is common in the cooling season. People can still be poisoned by CO by running a generator improperly during power outages. And this is often to power their AC. We should always be on guard against CO poisoning.

Spring is finally approaching and it is time for your furnace to get its well-deserved rest after keeping you warm indoors all through the winter months. As your heating system temporarily retires, you are now about to liberate your trusty AC.

It is your AC's turn now to impact the quality of the air you breathe inside your home. Because of the CO concerns you had with your furnace, you now wonder whether your AC could also be emitting CO or causing poor air quality. Should you really be worried about your indoor air quality?

Why Can’t Air Conditioners Produce Carbon Monoxide?

To answer this question, we have to make it clear first how carbon monoxide is produced. Next, we will explain how air conditioners function and see if there is a connection between the two processes.

Carbon monoxide (chemical formula: CO) is the resulting gas from burning fuel, along with nitrogen dioxide, particles, and sulfur dioxide. Fuel-powered appliances such as a furnace, wood stoves, gas stoves, ovens, grills, clothes dryers, water heater, power tools, lawn equipment, and motor vehicles are great producers of CO.

Heating devices such as fireplaces, furnaces, boilers, and generators provide us warmth through a continuous combustion process, which inevitably leads to CO production. This is why levels of CO indoors can significantly increase during cold seasons.

Now that we narrowed down the causes of carbon monoxide emission, let's look at how air conditioners make your home cooler.

Instead of relying on gas or fossil fuels, most air conditioners are powered by electricity. The cooling process begins when your AC draws in the warm and humid air from your living spaces through the vents. Once the warm air gets inside the AC, the heat is absorbed by the evaporator coil that contains the cooling agent called refrigerant. When the heat is removed from the air, the cooled air is distributed throughout your home through the air ducts.

As you can see, nowhere in this process does the air conditioning unit require the burning of fuel or any fossil fuel for that matter. So your home AC is physically not capable of producing CO and poisoning your family with the chilled air it releases.

The truth of the matter is, when the heating season is over, most gas-burning appliances such as furnaces, boilers, and fireplaces are made inactive or put away because there is less need for them.

Does that mean you are really out of the woods from being exposed to CO poisoning during the AC season? Not quite yet.

An Air Conditioner With A Carbon Monoxide Poisoning Warning

Many years ago there were air conditioning units that could produce CO. Natural gas air conditioners produce carbon monoxide and was an available home cooling source during the 1960s. These units fell out of favor due to the dangers, costs and environmental factors.

Recently though there has been some experimentation to bring back natural gas air conditioners.

Home air conditioning systems for the foreseeable future will remain electric and safe from a technology that produces carbon monoxide. But that doesn't mean you shouldn't be on guard if the "latest and greatest" is being offered.

Detecting Carbon Monoxide Leaks

What makes carbon monoxide really sneaky and dangerous is the fact that you cannot see, smell, or taste its presence. Without the help of a carbon monoxide detector, it is virtually impossible to detect a carbon monoxide leak.

If it's already too late, members of your family may experience the symptoms of carbon monoxide poisoning such as headache, dizziness, nausea, flu-like feeling, tiredness, confusion, stomach pain, and shortness of breath. Prolonged exposure to CO may even lead to comatose or death.

This poisonous air can roaming silently inside your house so it goes without saying then that it is extremely critical to detect it.

Sure, your heating system is turned off but there are other sources of CO that could still be active even in the spring and summer seasons.

Some families enjoy camping and barbecue parties in the summer right at their own backyards. These recreational activities usually involve the use of grills, oil lamps, portable heaters and gas stoves which produce a significant amount of CO.

During power outages, some households also use a generator to keep their AC running. If these generators are not maintained or misused, they can cause carbon monoxide poisoning.

Conclusion and HVAC Safety Tips

An air conditioner cannot produce carbon monoxide on its own. But you should never let your guard down against carbon monoxide poisoning, heating or cooling season. True, your air conditioner will not give off CO but an ill-maintained and improperly used generator and other fuel-burning appliances can cause poor indoor air quality and still endanger your family's health.

Stay up to date with HVAC safety tips and if you're concerned about CO, have an air conditioning repair tech test for carbon monoxide leaks. A quality HVAC company will always be ready to perform carbon monoxide testing no matter the season.

Make sure the carbon monoxide detectors in your home are working. And for the love of Pete, do not run a generator indoors like in your garage or basement.

Allergies are always annoying and inconvenient, regardless of what form they may come. They make even simple everyday tasks difficult to accomplish. But what is more troubling is the thought that the very thing you depend on warmth and comfort may trigger or exacerbate your family's allergies. Can a furnace cause allergies?

Your furnace cannot be the source of your allergies if it is properly and regularly maintained. A well-maintained central heating system can even help prevent the spread of allergens in your breathing space. On the other hand, a poorly maintained furnace can host various harmful particles in its dirty filters or air ducts that can trigger or aggravate existing allergies.

can a furnace cause allergies

Before we dive into the deep-seated link between allergies and the state of your furnace, let's look into this very common yet extremely irritating natural bodily reaction: Allergies.

A Rundown on Allergies

The American Academy of Allergy Asthma & Immunology (AAAI) describes an allergy as a chronic condition that can make you miserable in its mildest form but can put your life in danger in severe cases.

It all starts with our immune system, hardwired to protect our body from harmful intruders. Its troops of antibodies are always ready, day and night, to fight these toxins and expel them from our system.

This defense system works beautifully as a machine, except when it is the case of an allergic reaction. Some seemingly harmless things like dust, pollen, and pet dander can be mistaken by our immune system as dangerous invaders and attack them. Mold spores, dust mites, and different kinds of insects and their droppings are indeed disgusting but they can definitely cause an alarm to a hyperactive immune system.

These "invaders" when inhaled are now targeted as allergens. Our antibodies rushed in to eradicate these particles but they release histamine in the process. Histamine is a chemical compound that produces allergy symptoms such as sneezing, coughing, itchy red and watery eyes, sinus congestion, or runny nose.

The situation can turn from bad to worse when mild allergic reactions become severe allergies. Allergy sufferers can experience anaphylaxis or the critical and fatal kind of allergy. This may manifest in difficulty in breathing because of the inflammation of the nasal passages, throat, and tongue, low blood pressure levels, skin rash or hives, vomiting, and diarrhea. Continued exposure to allergens without immediately administering proper allergy medication can be deadly.

Now that we have a clearer understanding of allergies, let's shift our focus on how regular maintenance, or lack thereof, can either help prevent an allergy attack or make allergies worse.

How Can a Well-Maintained Furnace Help Prevent Allergies?

Seasonal allergies are a kind of sensitivity to allergens that only happen at specific times of the year. For example, pollen or the minuscule grains of seeds produced by flowers, trees, and other varieties of plants is the number one irritant that sets off summer and spring allergies. Meanwhile, the culprits for most winter allergies are dust, dust mites, and mold particles.

How does your heating system protect you from these common allergens? There are at least three ways:

How Can an Unmaintained Furnace Cause Allergies?

It is super easy to just ignore your furnace once the warmer months arrive, cover it up, and hide it away. But when the cold air returns, many homeowners simply do not bother to check the state of their heating system before turning it on. The result is incessant sneezing, coughing, and wheezing which they usually blame on the change of weather.

This vicious cycle continues for years until the heating system never gets thoroughly cleaned and maintained which poses a great risk to your family's health.

How exactly does a neglected furnace prompt your allergies?


Allergies are never fun. But many people learned to live with them by avoiding allergy triggers as much as they can. If you or any of your family members are vulnerable to indoor allergies we discussed above, make it your goal to subject your furnace to proper maintenance at least once a year by a qualified professional.

Whether your furnace is old or a newer high end variable speed furnace, the advice is the same.

A well-kept furnace can be your friend that keeps allergies at bay or an enemy that triggers allergy attacks.

It is a general opinion that the older something gets, the less efficient it becomes and the more likely it can bring you problems. Most people apply that idea to their gas furnaces and constantly fear that their old heating system will endanger their family's health. But is that really so? Can old furnace cause health problems?

An old furnace can cause various health issues if it is not properly and regularly maintained. But the same is true even with new high end furnaces, like a multi-stage variable speed furnace. Without thorough cleaning and checkup, simple mechanical problems will develop into serious complications that can impact your household's health and well-being.

can old furnace cause health problems

If you search on the web, "Can my old furnace make me sick?" you will surely be bombarded with claims that your trusted furnace for many years will put your health at risk. This will then be followed by not-so-subtle recommendations to replace it with the latest models. Sadly, many took the bait without thinking it twice.

But is there truth to it? Can an old furnace make you sick, or at least sicker than a new furnace could?

Are Old Furnaces Riskier Than Newer Ones?

The answer is not necessarily. An old furnace does not pose more health risks compared to a new one if the former is regularly and properly maintained. Conversely, whether your central heating system is old or new, it can endanger your family's well-being if it lacks routine maintenance by a qualified expert. 

To illustrate: An aged person may still have a good quality of life and function well if he has healthy habits and practices and maintains regular checkups with his physician. On the other hand, a younger person's health and lifespan may suffer if he does not care for his body well enough or neglects to go to medical professionals for help if he has health issues. 

A certified HVAC professional is like a skilled doctor that detects seemingly minor problems with your furnace early on and prevents them from becoming serious repair issues. Without his help, you may be tricked by quacks to throw away a perfectly good heating system simply because it has advanced in age.

How Can Regular Maintenance Help Your Old Furnace?

Heating, ventilation, and air conditioning systems should be checked regularly at least once per year by your trusted contractor. Its overall efficiency and length of life depend greatly on routine maintenance that is expertly done.

How can regular maintenance actually help your central heating system, new or old?

A whole lot, actually. Besides the general furnace inspection, calibration, and testing of the efficiency and safety of your furnace, a responsible contractor would lubricate the components, remove blockages and debris from the vents and blowers, clean or replace the air filters, check and fix any minor electrical issues.

If your furnace is always in its tip-top shape, you will spare yourself from expensive furnace repair costs and financial problems due to outrageous energy bills. Yes! A heating system that is poorly maintained consumes more energy than it should, causing an increase in your utility bills.

But what really matters is how a regularly maintained furnace impacts your family's health. Let's look at some ugly effects on your wellness if you neglect to maintain your central heating equipment.

Health Hazards of an Unmaintained Furnace

Allergic Reactions

The most common household air pollutants are dust, pollen, animal dander, dust mites, and every other kind of dirt that circulates the air.

True, your furnace filter can do an excellent job of trapping harmful particulates from your breathing space. But imagine all these indoor air pollutants clogging up your dirty filter and air ducts because you fail to have them cleaned? 

No wonder some residents start to sneeze, cough, have red, itchy, and watery eyes, runny nose, and throat irritation as soon as the furnace is turned on. These are classic signs of an allergic reaction.

Dirty air ducts and filters that can trigger allergies and respiratory diseases can easily be restored to clean and working order by your trusted contractor through regular maintenance.

Respiratory Diseases

Allergy attacks triggered by indoor air pollutants may be remedied by over-the-counter antihistamine meds, but long-term exposure to airborne toxins like dust mites and animal dander can lead to serious respiratory infections.

Rhinitis is one of the most common respiratory diseases you can catch from being exposed to pollen from plants, dust mites, mold, cockroach waste, and pet hairs. These irritants can cause your mucous membranes to swell, which manifests in a stuffy or runny nose, sneezing, and itchiness of the eyes and throat.

Allergic asthma can also present if a person inhales common airborne toxins. This type of asthma may manifest in shortness of breath, coughing, throat irritation, wheezing, rash, or hives. Children, pregnant women, and older ones with other types of asthma may feel much worse after being exposed to a breathing space with poor air quality.

You may also be putting your family at risk of acquiring other types of lung diseases and respiratory issues such as bronchitis, sinusitis, and pneumonia by not paying attention to the cleanness and maintenance of your furnace. 

Carbon Monoxide Poisoning

By far the most dangerous health hazard a neglected furnace can bring to your family is carbon monoxide poisoning. As expected, many websites use this possible threat as one big reason to replace your old furnace. What they fail to mention is that even modern furnaces are susceptible to this kind of problem.

The existence of carbon monoxide (CO) in a home where gas appliances are used is common. Specialists in cooling and heating equipment say that 9 parts per million of CO is still safe for an indoor setting within 8 hours, while 800 ppm of CO can kill you within minutes.

Faulty heating systems are a common source of high levels of carbon monoxide which can make any household vulnerable to health problems such as carbon monoxide poisoning. This typically happens when you have an unchecked heat exchanger that developed damages and breaks over time,  which can leak a considerable amount of these toxic gases.

The following are the usual symptoms of carbon monoxide poisoning: the feeling of getting sick from flu, headache, stomach pain, dizziness, weakness, vomiting, chest pain, and disorientation. In worst cases, excessive carbon monoxide exposure may lead to loss of consciousness, comatose, or fatality.

Install a carbon monoxide detector in your living and sleeping areas to monitor the levels of this toxic gas in your home. Be wary of the beginning symptoms of carbon monoxide sickness and go to the emergency room.

As for the carbon monoxide leak in your furnace, contact a certified technician to deal with the problem. More to the point, it could have been prevented by routine and proper maintenance. Making sure that there is no chance of something causing carbon monoxide poisoning would be one of the first things certified expert heating technicians would look into.


We will never get tired of saying that the age of your furnace is NOT what's putting your health at risk. How long heating equipment has been in operation has little to do with health and safety concerns. It is the lack of proper and regular maintenance by a quality contractor.

A professional and certified expert will not rush you into replacing your old but still efficient heating system but work with you in keeping your family safe and healthy with a well-maintained furnace.

Some scams are so well known they're more jokes than actual threats now. Not too many people are falling for the Nigerian prince email scam or paying extra for an "undercoat" on their car anymore.

But there are still some slick sales pitches that take our hard earned dollars faster than you can say "upgraded charcoal HEPA cabin filter" (a friend learned that $60 lesson on their last oil change).

So when you're told you should get regular tune ups on your furnace, it's natural to question if it is really necessary or just a scam to drum up repeat business. Is a furnace tune up worth it?

Yes, furnace tune ups are worth it. Regular preventive maintenance can make a significant difference in the longevity, efficiency, and safety of your HVAC systems. A well maintained system can last at least 20-25 years as opposed to only the 12 - 15 years that many HVAC contractors claim.

is a furnace tune up worth it

There are even more immediate benefits like preventing costly emergency repairs and lower monthly energy bills. But can't a handy homeowner clean and inspect a furnace themselves? And if not, how do you know the tune up you're paying for is actually delivering on all these promises? 

How Does a Tune up Help?

First, lets take a closer look at those amazing claims a little maintenance is said to accomplish. 

Longer Equipment Life

Almost all mechanical systems will benefit from maintenance. Imagine if you never got an oil change on your car. Just as driving your car with old, dirty oil can cause extensive damage so can running running a furnace with a build-up of dust and debris.

A dirty furnace or clogged furnace air filter causes the equipment to work harder and harder to keep your home heated. The unnecessary wear and tear can harm the overall health of the equipment and shorten it's lifespan by almost half.

Energy Efficiency (aka Monthly Energy Bills)

Most of the furnaces installed in the last 10 years would be considered "high efficiency". However, the efficiency touted by many manufacturers are based on the equipment running at peak performance. It's one of the reasons why all HVAC manufacturers recommend annual inspections.

The promised savings on energy consumption will quickly disappear when the equipment has to work harder due to poor maintenance.

Annual maintenance can help your heating and cooling equipment use less energy. This sometimes pays for itself in operating cost savings during the peak season alone.

Fewer Emergency Repairs

Maybe you're not planning on staying at your house very long so you're not worried about making a furnace last 20 - 30 years. Maybe you don't have a high efficiency furnace and the difference in monthly heating costs isn't enough to convince you to drop dollars on "just maintenance".

The more immediate benefit of regular maintenance is noticed in avoiding costly repairs. For example, one of the most common causes of furnace breakdowns is a dirty flame sensor. Any thorough furnace tune up performed by a qualified HVAC technician should include cleaning the flame sensor.

And with the complications with newer equipment, like the problems with 2 stage furnaces, you'll want to prevent as many problems as possible.


We all want to feel safe and secure in our homes. Most of us don't think about what unseen hazards are around us on a daily basis because how would we ever relax.

Not to keep you up at night but the heating and cooling system in our home is more likely to cause health issues or even death than almost any other component.

For instance, cracked heat exchangers can leak lethal amounts of the colorless and odorless gas carbon monoxide. The symptoms of carbon monoxide poisoning can hard to detect and are often mistaken for the flu or migraines.

Again, testing the level of carbon monoxide should be included in a thorough tune up performed by HVAC technicians. That is just one potential hazard but I believe that piece of mind is worth the $100 - $200 the average annual maintenance costs.

Can't a Homeowner "DIY" a Furnace Tune up?  

It depends on what kind of tune up you are getting. Maybe you got a great coupon is this month's ValPak - $49 for a furnace or air conditioner clean and check!

While it may seem like terrific deal this version of a tune up is likely little more than a basic cleaning of your furnace, a little vacuuming, and a laundry list of recommended repairs that you may or may not need.

At such a low price the company isn't even covering the cost of sending a tech to your house let alone having them complete a thorough tune up of your furnace. At that point you could have definitely done it yourself and saved the $49.

Most companies that advertise a deal like this also offer "real" HVAC tune ups for a higher price or as part of a preventative maintenance agreement. These visits can cost about $100 - $200 depending on where you live, the type of equipment, etc.

With a little advance preparation and the right questions you can definitely find a heating contractor that will deliver all the benefits of regular maintenance.

A qualified heating contractor will have tools required to do a proper furnace tune up that the average homeowner wouldn't invest in or maybe even know how to use. Most of us don't have a combustion analyzer laying around to measure combustion gases (including carbon monoxide).

Even something as simple as cleaning a flame sensor is often misunderstood. Most DIY information on the internet will tell you to lightly sand your flame sensor but that is incorrect. You don't need to sand a flame sensor and you are actually damaging it. This will require it to be replaced much sooner and more often than necessary. 

Finally, a qualified technician can tell a lot about how your system is running when performing a tune up. They will notice if there is excessive carbon buildup in your unit, if the air filter is dirtier than normal, if the blower motor sounds off, or even something subtle like the pilot light flickering abnormally.

This allows them to make suggestions for your system before something goes wrong and often they can offer discounts on repairs when done while they're already there for your annual tune up.

How Do I Make Sure I'm Getting a Comprehensive Tune up?

While this isn't a complete list it covers the main areas that need to be checked for a good furnace tune up...


Furnace tune ups are highly recommended. They improve indoor air quality, prevent breakdowns, help the furnace run safer and save money on energy bills. Whether your furnace is new or old, seriously consider getting on a service plan with a good HVAC contractor or at the very least setting a reminder to have annual inspections on your furnace.

Storm season is once again upon us. The peak season for floods and other weather-related damage.

Before home owners can start cleaning up after a flood, they need to know whether the home is safe. Most flood insurance policies have a provision for protection for damage to furnaces, but only if a homeowner takes certain steps before turning the power back on.

After a flood, homeowners need to take precautions to protect the health and safety of their family.

One of the most important things for homeowners to do is inspect the home’s furnace.

The common question is, can a furnace survive a flood?

Yes, it can. BUT...and this is a BIG BUT...It will greatly depend on your style of furnace and the level of water it was exposed too.

Here are 3 things to watch out for...

can a furnace survive a flood

Should I Use My Furnace After a Flood?

First things first, DON'T try to use your furnace.

Some think that turning on the furnace to see if it runs classifies as "testing" it. That's a bad idea. Just because it starts doesn't mean it's safe.

There could be multiple problems with electrical components that would allow the unit to fire but still be very dangerous.

This is especially true with new furnaces that are more complicated. This adds to the list of 2 stage furnace disadvantages that you need to consider when buying a new furnace.

Corrosion within certain components, like the gas valve, can cause them to operate at first but then stick in an open or closed position. If it sticks in an open position it could lead to a build up of gas and then an explosion.

It's not worth the risk of damaging the equipment or yourself. The best thing to do is to shut off the power source to your home (if possible). Then call a professional that can give the furnace a thorough inspection and let you know the damage.

What To Do If Furnace Was 100% Submerged

Drop back and punt.

If you had a flooded basement and your furnace was completely submerged, sadly, nothing can save the equipment. Manufacturers will even void any warranties if the equipment has been in a flooded basement.

Keep in mind that most furnaces today are only about 36" tall. So a basement with three foot of water means a complete loss of the furnace.

This often means replacing the air conditioning system as well. Air conditioners have an integral part sitting on top of the furnace. If that was submerged, you'll need to replace that as well.

An HVAC system that's experienced this kind of flood damage is a major loss.

What To Do If Furnace Was Partially Submerged

This is where things can get tricky. You'll definitely need a qualified HVAC professional out to inspect your system and give you your choices.

As a rule of thumb, if your furnace is in the basement and you get less than 18 inches of flood water, the option to keep your furnace should be available.

But it will require replacement of ANY and ALL electrical components and safety controls that came in contact with flood waters.

In addition, any metal that came in contact with water needs to be cleaned and sanitized. This includes all components of the blower and blower wheel in the lower part of the furnace.

In some furnaces, there is also a layer of insulation on the inside of the metal cabinet. Any insulation that has water damage will need to be removed. The removal of the insulation in the bottom of the furnace will have little to no effect on its operation.

Water doesn't only mean wet floors and walls. It also means that harmful bacteria and mold can grow and flourish in places such as your furnace. This is why a thorough cleaning is so important.

What About Other Appliances

Our focus has been on furnaces in a basement. But this information can be used for air handlers, water heaters or any appliances in a basement or utility room that have been exposed to water damage from flooding.

Keep in mind, any electrical controls exposed to flooding must be replaced. Any other working elements that the water reached must be replaced. Anything that can absorb water must be thoroughly cleaned and sanitized or it must be removed.


The safety of your home and family is first. Do NOT try to turn on your furnace. If you're in this situation, call your insurance provider first. After they give you the information you need to move forward, get in touch with a professional HVAC contractor and have them give your furnace a full inspection.

Copyright 2022 The Comfort Academy