What is a Good Percentage to Set a Dehumidifier?
A dehumidifier is the best appliance for reducing the relative humidity in the house. Maintaining good humidity levels in the house is key to your health, comfort and also preventing the house from damage.
So, what is the best dehumidifier setting to ensure that you get the best out of your dehumidifier, you are comfortable, you are not likely to get sick and that your house will not be affected by moisture in any way?
A dehumidifier should be set at between 30% and 50% relative humidity. In winter, a dehumidifier should be set at between 30-40% while in summer it should be set at between 40-50%. In a basement, a dehumidifier should be set at 40% in summer and 30% in winter.
Dehumidifiers should be set to the ideal indoor humidity. The ideal indoor humidity is usually 30-50% although some people wouldn’t mind relative humidity as high as 60% or as low as 20%.
Ideal indoor humidity and therefore the best dehumidifier setting is given as range instead of a specific figure because just like temperature, different people find comfort at different settings. Also, the ideal indoor humidity also depends on the outside temperature.
Dehumidifiers should be maintained at relative humidity of between 30% and 50%. Above 55%, your body may start feeling sticky and the moisture in the air also traps pollen, dust, smoke and also encourages growth of mold, mildew and dust mites, which can trigger asthma and allergies.
As I have mentioned, dehumidifier settings may also depend on season. As such, you may need to adjust your dehumidifiers setting between winter and summer. The location is another thing to consider. A dehumidifier in the basement and another in the living room may need different settings.
What Should a Dehumidifier Be Set at in Winter?
It is important to remember that relative humidity is not constant throughout the year. Relative humidity changes with changes in temperature.
For that reason, you will notice that relative humidity is higher in summer more than in winter. That is because hot air has more potential to hold moisture that cold air. When warm air is subjected to low temperature like a glass window, the air loses the water it’s holding through condensation.
Relative humidity also varies from location to location. Areas that are close to water bodies have higher relative humidity levels than areas that are far away from any water body.
That is the reason why relative humidity is higher in Florida than in Arizona. The average relative humidity in Florida is 74.5% while that of Arizona is 38.5%.
As you can see, folks in Arizona may not need a dehumidifier at all. If anything the air in states such as Arizona, Utah, New Mexico and Nevada is so dry that folks there need to buy a humidifier to increase relative humidity.
Low humidity is just as bad as high humidity. It can cause the skin to dry and become itchy, eyes become dry and irritated, you suffer from respiratory infections, you nose bleed constantly, there is static electricity in the house and wood products shrink and crack.
People living in these arid areas therefore don’t need a dehumidifier especially in winter. Using a dehumidifier will make the air even drier which is bad for their wellbeing and properties.
Folks living in humid areas like Florida will almost always need a dehumidifier throughout the year. Although relative humidity will be lower in winter more than during the summer, there is always a chance that it will be more than the ideal levels.
In Florida for example, relative humidity in winter can be as low as 53% or as high as 87%. With such high relative humidity levels you will definitely need a dehumidifier to bring it down to the desired levels.
Since comfort (and mold prevention) is a function of both temperature and relative humidity, ideal indoor humidity in winter should be lower than that of summer by about 10%. Therefore, the recommended dehumidifier setting for winter should be between 30% and 40%.
It is important to remember that winters are not the same everywhere. In some areas the air is quite dry while in others the air is moist/humid. The best you can do is to measure the humidity in your house using a hydrometer to know if you need a dehumidifier.
If the relative humidity is higher than 40% in winter, you may need a dehumidifier to remove the excess moisture. On the other hand, if it is lower than 30% you may need a humidifier to add some moisture in the air.
As I mentioned, the ideal indoor humidity also depends on the outside temperature. In some cases, you may need to set your dehumidifier to a relative humidity level lower than 30% as shown in the chart below.
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What Should Dehumidifiers Be Set at In Summer?
Summers are known for high humidity. You are therefore likely to use a dehumidifier during summer more than in winter. Sometimes you don’t even need it in winter.
To start with, we use air conditioners during summer. Air conditioners will also dehumidify your house apart from cooling it. Most air conditioners will remove between 5 and 20 gallons of water from the air in a day, reducing humidity from 80%s to 60%s.
However, even a relative humidity of 65% is still high and that is why you need a dehumidifier. So, what settings should a dehumidifier be set at during summer?
The best dehumidifier settings for summer is between 40% and 50%. A relative humidity of 40-50% in summer is comfortable for you, good for you house and possessions and importantly it will not allow mold to grow.
Again, there are people who will find comfort at relative humidity levels of between 50 and 60%. As I said, people are different and what works for someone else may not work for you.
Of course maintaining humidity at 55% is cheaper than having it at 40% so if 55% is the ideal relative humidity for you then set your dehumidifier to 55%.
Avoid the temptation to set your dehumidifier too low. Not only is that unnecessarily inexpensive but it can also dry the air up resulting in the negative effects of low humidity.
Again, if you live in an arid area, there is a good chance that you may not need a dehumidifier. An air conditioner is usually enough to cool and dehumidify houses in such locations.
What Should a Dehumidifier Be Set at in Basement?
The one place in your house where water (both from inside and outside) is more likely to accumulate is the basement. Most folks actually buy dehumidifiers to place them in the basement.
However, the settings of a dehumidifier in a basement should not be any different from any other room in the house. The idea is to maintain an ideal humidity level in the basement and not to dry it out.
There are folks who would be tempted to set basement dehumidifiers to a very low settings but that can do more harm than good. So, what is good dehumidifier setting in a basement?
Basement dehumidifiers should be set at 30% during winter and 40% during summer. At between 30% and 40%, the humidity will be high enough to prevent wood and walls from cracking, but it will also be low enough to prevent growth of mold, mildew and dust mites.
So, how can you tell that the humidity levels in your house/basement are high and you need to adjust a dehumidifier down accordingly? Well, the following are the signs:
- Stuffy/clammy air
- You feel uncomfortable
- Musty smells in the house
- Mold growth
- Water stains in walls and ceilings
- Condensation on windows
- Worsening asthma and allergies
- Swollen wood/furniture
- Pipes dripping water
And what are the signs that the humidity is too low and you need to adjust the dehumidifier settings upwards or even turn it off entirely? These are the signs:
- Dry and itchy skin
- Respiratory infections
- Cracked wood, furniture and artwork
- Dry/irritated eyes
- Static electricity
- Nose bleeding
- Books become brittle
Now, apart from the discomfort that is associated with high humidity, the other main reason we buy dehumidifiers is to prevent mold growth. But what are the conditions necessary for mold growth? They are:
- Warmth (60-80 degrees Fahrenheit)
- Moisture (RH above 55%)
- Mold spores
Of the above conditions, the only thing we can regulate without affecting our comfort is relative humidity. We need warmth and air oxygen too. Mold spores are always present in the air and darkness and a source of food are also in plenty.
This is why we need to properly adjust a dehumidifier to keep mold, mildew and dust mites at bay. Apart from settings, you also need to place a dehumidifier in a good spot to reap the maximum benefits from it.
To start with, a dehumidifier should be placed on the floor instead of an elevated surface. Remember that warm air rises. You therefore need a dehumidifier on the floor to dehumidify the humid and dense air.
Dehumidifiers should also be placed centrally in the basement, away from any surfaces. If the dehumidifier is placed close to a wall or wood product, it can pull it moisture causing the wall or wood to crack.
Locating a dehumidifier in a central place also allows it to pull in air from all over the basement or room and therefore avoid dehumidifying some areas more than others.
Apart from dehumidifiers, there are other ways you can use to reduce the indoor humidity. I wrote a comprehensive guide on that in this post.
The best dehumidifier setting would be between 30% and 50%. Try and find a comfortable setting for you within that range. Avoid over dehumidification as it can have worse problems that those you are trying to avoid.