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HVAC Humidity Control: Controlling Humidity With Your HVAC System

Tired millennial woman suffers from stuffiness and an inoperative air conditioner, waving blue fan sitting on couch at home working on laptop computer. Overheating high temperature, hot summer weather
Aug 03, 2022 | By  right-time

Let’s face it, the humidity level in your home is just as important as the temperature. A home with air that’s too dry or too moist can make for an uncomfortable environment. Luckily, 669 Heating & Cooling is here to explain how you can control the humidity in your home with your HVAC system. Keep reading to learn more about HVAC humidity control. 

Can you add humidity control to an HVAC system?

Some air conditioning units can dehumidify the air. However, their abilities are usually quite limited and certainly won’t be anywhere near as effective at controlling humidity as a humidifier. Thankfully, there are humidifier attachments that can be added directly to your home’s HVAC system to improve indoor comfort. For example, if you have a central air conditioner in your home, you can add a humidifier to it. Doing so may not only improve the atmosphere of your home but also save you money and reduce damage to your property. 

Is an HVAC system enough to control humidity?

Certain air conditioners can dehumidify the air to a degree, though an air conditioner’s dehumidification properties are more a side effect of how they function than anything else. That is why, in most cases, a traditional HVAC system without a humidifier attachment, is not enough to effectively control the humidity levels in your home. While an air conditioner has many other benefits (namely, cooling the air in your home), its ability to dehumidify the air is typically not sufficient (especially if the relative humidity is above 60%). 

What is the ideal humidity for maximum comfort?

The ideal humidity level for maximum comfort varies from person to person. The ideal relative humidity level for human health and comfort is between 30% and 60% (between 45% and 55% is the recommended range for most people). However, the ideal humidity for maximum comfort also depends on the time of year. For example, winters are colder and naturally have less humidity than summers, where there is more humidity in the air. For this reason, homeowners might need to adjust the humidity levels in their homes according to the season.

What is an appropriate humidity level for a house in Winter?

The appropriate humidity level for a house in winter is between 25% and 40%. This is the ideal HVAC humidity setting for winter that will allow you to maintain a comfortable and warm home. However, it is not so high as to leave condensation on the windows. 

What is an appropriate humidity level for a house in Summer?

The appropriate humidity level for a house in summer should be slightly higher than that of the winter, between 40% and 50%. Avoid humidity levels above 60%, especially in the summer, as it can lead to discomfort when sleeping, uncomfortably muggy conditions, and even damage to wood floors or furniture. 

Will the humidity rise if the heat is turned up?

Contrary to popular belief, heating the air actually lowers the relative humidity. This is because, as the temperature of the air increases, the air can hold more molecules, and its relative humidity goes down. The warmer the air, the greater its capacity to hold water. For this reason, heating systems should be used alongside humidifiers to ensure your home remains adequately humid throughout the cold winter months. 

Do HVAC systems dehumidify?

An HVAC system might be able to dehumidify your home to a degree. For example, an air conditioning unit can lower the humidity levels in your home. The air conditioner’s natural cooling process involves removing moisture from the air in your home, a process known as condensation that occurs through the evaporator coils. 

If you want to use your air conditioner as a dehumidifier, make sure to clean the air filter regularly, replace old filters, and inspect the ductwork for signs of damage (if you don’t have the time or energy to do this yourself, you can also book an HVAC maintenance service with AtlasCare). 

That said, some homeowners may find that the dehumidifying properties of their air conditioners are not sufficient. This is when purchasing a dehumidifier attachment might be useful. Dehumidifiers are much more effective at controlling the humidity levels in your home than air conditioners. Plus, when you add humidity to HVAC, you can adjust humidity levels year-round, not just in the summer when your air conditioner is on. 


How might changes in humidity impact my health?

Believe it or not, the humidity levels in your home can have a significant impact on your health and comfort level. Humidity affects how our bodies perceive temperature. Since warmer air can hold more water vapor, if the temperature drops but the water vapor content stays the same, the relative humidity increases. Conversely, if the water vapor content remains the same but the temperature rises, the relative humidity decreases. The more humid the air, the moister it feels, and the stickier, sweatier, and less comfortable we feel. When the humidity level of the air reaches 60% or higher, it is so high that our sweat will not evaporate, making us feel uncomfortable. On the other hand, when the humidity level is lower, such as during the winter, it can also cause discomfort since the lack of moisture in the air is known to dry out our skin, eyes, and nasal passages. Further, when humidity levels are too high or too low, it can negatively affect our sleep quality, aid in the transmission of viruses, and even lead to the growth of mold, bacteria, and fungi. For these reasons, controlling humidity with your HVAC is of the utmost importance. Keep reading for more information on the specific impact of humidity levels that are too high and humidity levels that are too low. 

If humidity levels are too low

Humidity levels that are too low can have adverse health effects ranging from dry skin and chapped lips to itchy eyes, nose, and skin. It can also lead to a build-up of static electricity and aid in the spread of viruses and bacteria. Lastly, humidity levels that are too low may also damage wood floors, furniture, or musical instruments. Please note that homeowners should avoid the humidity levels of their homes dropping below 30%. 

If humidity levels are too high

Humidity levels that are too high (e.g. 60% or higher) can also impact a person’s health and home. For example, if the humidity is too high, it can lead to mold and fungi growth, discomfort when sleeping (which possibly translates to a lower quality or shorter sleep), and uncomfortably muggy conditions. It can also cause moisture stains on walls, a musty smell in your home, commendation on the windows in the winter, and damage to wood floors, furniture, or musical instruments. 

How can I find out what my humidity level is?

There are many ways to find out the humidity level in your home. The first is with a hygrometer, which is a device that monitors the humidity levels in your home (it looks very similar to a thermometer). If you do not have a hygrometer, you might be able to download a free app onto your smartphone that reports on temperature and humidity using your phone’s built-in sensors. 

Nowadays, some modern HVAC systems and smart thermostats offer humidity level readings, so if you have a new system or high-tech thermostat, you can also check there to see if it offers humidity level readings. 

In addition, there are several DIY humidity tests that won’t provide you with an exact humidity level but that can indicate whether the levels in your home are too high, too low, or just right One such example is the “ice cube in a glass of water” test, where you put four or five ice cubes in a glass of water and set it down somewhere in your house. Leave it there for five to ten minutes. If, after five or ten minutes, there’s condensation on the outside of the glass, it means the room has relatively high humidity. However, if there is no condensation on the glass, the humidity level is likely too low, or if there’s a lot of condensation on the glass and it resulted in a puddle beneath it, the humidity levels might be too high.

Finally, although lacking in precision, there are a few telltale signs you can look out for that might help you gauge whether your home’s humidity levels are too high or too low. For example, if you notice a musty odour, clammy skin, or foggy windows with lots of condensation, chances are the humidity levels in your home are too high. Oppositely, if your skin feels dry and itchy at home or you’re suffering from chapped lips or a scratchy throat, these could be signs that the humidity levels in your home are too low.

Why is my HVAC not removing humidity?

Is your HVAC system failing to effectively remove humidity from the air in your home? Then you’re probably wondering why. Below is a list of the most common reasons that an HVAC system may not be removing humidity. 

Your AC is too big

An oversized HVAC unit is a common culprit when it comes to air conditioners not removing humidity. Although you might think the better the unit, the better, this isn’t the case. Air conditioners that are too big will struggle to regulate both temperature and humidity level. Since larger units tend to be more powerful, they will cool rooms quickly and turn on and off frequently. A larger AC unit’s cooling capacities might be so powerful that it doesn’t run long enough to effectively dehumidify your home.

Negative air pressure

Another reason your HVAC unit may not be removing humidity is due to negative air pressure. Negative air pressure develops when there is too much venting and it can lead to humidity climbing to extreme levels.

Leaky ductwork

Anytime moist air enters your home, such as via leaky ducts, it can compromise your humidity levels. So if the air ducts in your home have a leak, the humidity levels in your home could become so high that the air conditioner isn’t strong enough to remove the amount of moisture. 

Limitations on speed control

If you have a basic HVAC unit that only offers one speed or has a simple on/off function, it likely will not be able to control the humidity levels in your home very effectively. Without more speed options, your unit likely turns on at full blast until it reaches the desired temperature. As soon as the desired temperature is reached, the unit turns off. This fast cycle likely doesn’t give the air conditioner enough time to pull moisture from the air and dehumidify the home.

Thermostat setting error

Turning your thermostat to the wrong setting by focusing solely on temperature rather than humidity is a common mistake. For example, running your AC unit in fan mode might increase the airflow in your home, but it will also increase the humidity level. Therefore, choosing the right thermostat setting is crucial to controlling the humidity.

Your HVAC is too old

Old or outdated HVAC units aren’t as energy-efficient as new ones, which means they likely won’t not be able to remove moisture very well. So if your air conditioner is over 10 or 15 years old, it might be time to invest in a new one. 

How can I improve HVAC humidity control in my existing system?

You can improve the HVAC humidity control in your existing system by following the three tips below.

Maintain a spotless coil

Keeping your air conditioner’s evaporator coil clean is crucial to improving or maintaining HVAC humidity control. It doesn’t take long before evaporator coils are covered in dirt, dust, and debris. However, when this occurs, your AC unit will not be able to remove the heat and humidity in your home the way it’s designed to. To maintain a spotless evaporator coil, change or clean your air filters regularly. 

Modify the fan’s airflow and speed

Adjusting the fan’s airflow and speed can also help improve HVAC humidity control. When it comes to humidity removal, the slower the fan speed, the better. For example, if your system currently operates at a speed of 400 CFM per ton, consider reducing it to 350 CFM per ton. Doing so will reduce the fan’s airflow, allowing the evaporator coil to cool down, which in turn, enables it to remove more moisture from the air.

Purchase a maintenance plan

One final way to improve the HVAC humidity control in your current system is to purchase a maintenance plan with a professional HVAC company like 669 Heating & Cooling. HVAC companies like 669 Heat offer a wide range of preventative maintenance services that can increase the lifespan of your HVAC system and help it function more efficiently (which translates to better humidity control and maybe even lower utility bills). Contact 669 Heating & Cooling to learn more about our HVAC maintenance plans.

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