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Honeywell HUL535B Review: Great Humidifier for Breathing Problems

For anyone having asthma, allergies or sinus problems, humidifiers can be a perfect choice to make their necessary indoor stay a lot more comfortable. Cold mist humidifiers are especially recommended for this, as they will make the air really fresh and enjoyable, and new technology allowed humidifiers to become filter-free, which makes maintenance completely easy.

Such are also the claims for one of the best humidifiers currently on the market, the Honeywell HUL535B Cool Mist Humidifier, which we will today put to the test to confirm it is really as noiseless, durable and refreshing as people claim it to be.



This unit can hold 1 gallon (3.785 liters) of water, which is the standard capacity for most humidifiers. It means that the mist can be produced for 24 hours per one filling if uninterrupted, however this highly depends on how much moisture you want to output. If you plan on using the high misting settings, then the unit can output even up to 1.5 gallons of water per day.

Due to its lasting capacities, it is best when used in medium-size rooms. The multiple continuous working hours that the Honeywell Cool Mist Humidifiers provide can bring the moisture up to 60% fairly quickly. Also, the 1-gallon capacity makes this device easy to transport even when it’s fully filled with water, so it can be used in multiple rooms without any problem.

The transparent tank can help you keep track of the water levels by just a simple glance, without having to open it up.


As with many modern humidifiers, this unit produces no noise at all. The water is released from the tank to the water reservoir where it is broken down into the tiny droplets by high-frequency vibrations, which is a completely mute method. This makes it perfect for your bedroom or nursery room, as it won’t keep you awake at night. You won’t even know that it’s turned on! In fact, this unit is announced as one of the quietest humidifiers on the market. Perfect for keeping you cool and making you breathe easily even during those hot, dry summer nights.

The option that goes well with this one is its auto shut-down feature, which will help you relax and forget that you even plugged it in, without having to worry about checking water levels so you can turn it off on time. As this is a soundless device, this option is very useful as a lot of time people just don’t find it worth getting up every half an hour in order to check the time that it has left, in fear of it breaking.


The unit is recommended for medium size rooms sized around 150-250 square feet (15-20 square meters), which is the average size of most bedrooms and kids’ rooms. This makes it great for anyone who likes or has to spend a lot of time indoors, but the dry, stale air makes their headache and their nose becomes runny. As such, it is recommended for people with asthma, breathing problems or constant cough as it will provide quick relief. It is also great for office use, as the low mist settings won’t pose any problems for cables or electrical devices, and its lightweight of just 3.8 pounds will make it easy for you to move it around.

Also, the directional mist outlet is moveable so you can set the direction of this humidifier, which will help spread the mist around 180 degrees while also keeping the direct humidity source away from you.

How Does It Stand Out?

Auto shut-down

This unit will shut down on itself once it’s out of the water, which means that you don’t need to worry about it malfunctioning if it isn’t turned off on time.

Directional mist outlet

You can change the direction of the mist outlet, which helps you precisely decide which part of the room you want extra freshness on.

Ultrasonic humidification technology

The ultrasonic technology that this unit operates on renders the humidifying process completely soundless.

Two colors option

The Honeywell Cool Mist Humidifier comes in black and white, so you can make it not stand out inside of your artistically designed interior.


Is this device okay to run inside the office?

Yes, it is! We recommend that you keep humidity levels low and manually turning the unit off after you’ve reached the desired humidity levels, just to make sure that there is no water residue.

What is the white powder that remains in the room after the unit is shut down?

The white powdery stuff that you may see on your furniture or floor is simply the residue from the minerals in your water. If you are bothered by this, we recommend using distilled water.

Is it hard to clean?

No, it isn’t. The tank opening is wide enough for you to put your hand inside of it and clean it thoroughly, but you can also always just use vinegar.

Can you use essential oils with it?

It is not recommended that you put any oils inside of this humidifier – although from most people’s experiences it doesn’t really affect the misting function – and it also doesn’t have slots for scented pads.

Does it have any lights?

The device has a small, blue light on the switch, but apart from that it is unnoticeable in the dark, and even that probably won’t keep you awake at night. If you’re bothered by this, you can always put a small piece of tape on top of it, or simply turn the humidifier towards the wall.


The Honeywell Cool Mist Humidifier is a great device if you have any breathing problems such as asthma, regular cough or if dry air simply bothers you. It is completely quiet so it won’t disturb even the lightest sleep, while also being able to refresh almost any room in your house. Also, the simple design as well as it being filter-free makes the maintenance really easy and far from complicated, which means that you won’t waste a lot of time cleaning it or filling it up. The directional mist outlet makes it perfect for anyone’s need, as you can point in which direction you want the humid air to blow, without moving the whole device.

The biggest cons are that it isn’t really suitable for any kind of essential oils or pads, and that it does leave white powder across the room – which is easily preventable if you use distilled or filtered water instead of ordinary tap one.

Also, if we take the price of the device into consideration, we can safely say that this is one of the best filter-free cold mist humidifiers currently on the market.

if this humidifier is not what you were looking for, check out our Best Filterless Humidifiers post.

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