Why Is My House So Humid When The AC Is On?

You know the air conditioner is on and you know that it is working just fine.

So why is the house so humid and why are you still sweating through your shirt?

Unfortunately, this is a common issue and could be caused by a number of factors.

So, if you find yourself in this sticky situation, read on to learn more about what is causing it and, most importantly, how to get rid of the excess moisture in your home’s air.

Causes of High Humidity In Your Home

There are many reasons why your house is so humid even when the air conditioner is running.

It could be because of the amount of people in the house, the weather, or a lack of proper ventilation. But, for the purpose of this article, let’s talk about the less obvious reasons.

1. Oversized Air Conditioner

humidity in house because of wrong size air conditioner

Folks, this is where bigger is not always better. If your AC unit is simply too big (cooling capacity-wise and not the physical size) for your home, you may have inadvertently created a humidity problem.

Remember the condensation process to remove humidity we mentioned above? See, that process takes a bit of time.

However, with a bigger air conditioner, its powerful compressor turns on and off frequently and simply does not run long enough to accommodate the typical condensation process. Hence, the air inside your home retains most of its moisture.

To prevent this cause of humidity buildup, make sure that your air conditioner unit is the right size for the square footage of your home.

2. Air Conditioner is Too Old

As your air conditioner ages, its ability to effectively remove humidity will likely be limited by wear-and-tear. This is especially so if the unit has not been regularly maintained.

At this point, you really only have two options: repair or replace.

3. Negative Air Pressure

Do you know that sudden gust of air when someone opens the door?

That gust of air is created by the negative air pressure inside your house.

When there is negative air pressure, the air balances itself by drawing in more air from outside. So, if the weather outside is extremely humid, the incoming air brings with it that moisture, leaving your house feeling muggy.

This is usually because of poor design in the ventilation system and will require modification to the ventilation system in order to fix the problem – unfortunately, not a cheap fix.

4. Problems with the Evaporator Coils

If there is a problem with the evaporator coils of your air conditioner, this can also affect the humidity levels of your house.

An example of this is if there is frost on the coils. As the air cannot reach the evaporator coils for condensation, the dehumidification of your house is compromised.

5. Dirt, Dust, and Debris

dusty and humidity buildup

An old air filter is going to lose its effectiveness and will hinder your AC.

A regular change of HVAC air filter according to the manufacturer’s instructions will do wonders in controlling the humidity level in your house.

6. Leaks

Besides the above, the muggy feeling could also be from moisture entering your house through leaks, cracks, or broken pipes.

Make sure to intermittently do a full walkthrough of your house — checking for leaky pipes, loose tiles, blocked gutters, and other similar issues.

7. Rising Damp

Another serious issue that is potentially causing high humidity in your house is rising damp.

Rising damp, while rare, is a troubling form of dampness that affects the walls of the house.

It occurs when moisture from the ground travels up the wall through the pores in bricks and other porous building materials.

Signs of rising damp include mold, visible stains and wet patches, and deteriorating plaster and paint.

If you believe that the high humidity in your house is caused by rising damp, now is the time to bring in a professional.

The Solutions to a Humid House

You don’t have to live with a humid house. There are several fixes – some easy and some more time and money consuming.

1. Get the Correct Air Conditioner Size

Never install an air conditioner that is either too large or too small for your house.

To properly decide on the size of an air conditioner, you need to do some load calculation.

There are plenty of load calculators available online but it is always best to leave the calculation to experts and professionals.

Before buying that new HVAC system, consult with an experienced HVAC technician on what size is best for your house.

2. Consider Adding A Dehumidifier

dehumidifier to help reduce humidity

We are all at the mercy of Mother Nature and, sometimes, even the best and latest air-conditioner cannot fully control the humidity in your house.

In this instance, you can add a separate dehumidifier to your AC system, or buy a plug in unit to place in the most humid spots in your house, like the Vremi dehumidifier.

As the name suggests, a dehumidifier removes excess moisture from the air to reduce humidity.

3. Maintain Your Coils

If your evaporator coils are covered under a layer of dust and dirt, they cannot release heat and remove humidity as they should.

So, make sure to regularly replace your air filter. As long as the air filter is performing, the coils should remain clean.

4. Miscellaneous Tips

Apart from the above, there are also some other steps you can take to lower the humidity indoors.

This includes taking colder and shorter showers, refraining from boiling water and cooking on particularly humid days, growing plants that remove moisture from the air, and installing exhaust fans in the kitchen and bathroom.

How Does An Air Conditioner Remove Humidity?

First, let’s look at how the AC helps to get rid of humidity.

Now, contrary to what many people think, the air conditioner does not only continuously blow cold air into your home. Instead, most modern air conditioner units are multitaskers and are also responsible for regulating humidity and removing warm air.

So, how does the AC remove humidity?

To keep it simple, your air conditioner has evaporator coils that condense the water vapor from the hot and moist air. Once the liquid is condensed out of the air, the collected moisture goes to a drain that leads outside your home — making your home less humid.

Reduce Humidity For A More Comfortable Home

Now that you know the potential causes of why your house is so humid even when the AC is on, the next step is identifying the specific cause and addressing it.

If you ever feel the need to, make sure to call in the professionals. Do not underestimate the importance of achieving the right humidity levels in your home; many problems can be avoided by maintaining low humidity.

If you have any questions or would like to give us a tip that has helped you, please reach out and contact us. We love to hear from our readers!

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