Why it matters
The KZF ZG-521 Humidifier is an ultrasonic humidifier with a 4 liters tank, rated for 300 square feet.
Run time per fill, per the maker: 40 hours.
Aim for 40 to 60 percent relative humidity indoors: drier air irritates airways and skin, wetter air feeds dust mites and mold. Use distilled or demineralized water to avoid the white mineral dust ultrasonic mist leaves behind.
A full tank holds about 4.0 liters, which adds roughly 9 pounds of water to carry or lift to the sink and back.
Spread over 40 hours, that tank works out to about 100 milliliters an hour, the rate on the setting the run time was measured at; higher settings empty it faster.
Its tank of 4.0 liters is below the middle of the range we cover: 33 of the 78 humidifiers with a stated figure come in lower, and the range runs from 0.7 liters to 20.1 liters.
Its stated run time of 40 hours is above the middle of the range we cover: 37 of the 69 humidifiers with a stated figure come in lower, and the range runs from 10 hours to 130 hours.
Price-wise it sat in the cheapest third of the 74 ultrasonic models we cover when we checked; the button shows today's price.
It qualifies for our lists Best Humidifiers for Bedrooms, Best Cool Mist Humidifiers, Best Humidifiers for Babies and Nurseries, where it is ranked against every model that meets the same rule.
Who it's for, and who should skip it
Good fit if
- Dry winter bedrooms
- Owners who will clean it weekly
Look elsewhere if
- Rooms far larger than its rating
Pros and cons
Pros
- 4 liters tank
- Runs 40 hours per fill
- Rated for 300 square feet
Cons
- Needs regular cleaning to stay hygienic
- Ultrasonic mist leaves white dust with hard water
Limitations to weigh
- The KZF ZG-521 Humidifier listing states every figure we compare on; they are the seller's numbers, measured on the setting it chooses.
Specifications
The bracket shows where each figure comes from.
| Model number | ZG -521 | Retailer |
|---|---|---|
| Room coverage | 300 square feet | Retailer |
| Noise (seller) | Below 28dB | Retailer |
| Wattage | 25 watts | Retailer |
| Capacity | 4 liters | Retailer |
| Run time per fill | 40 hours | Retailer |
Alternatives worth comparing
More room humidifiers we cover
Final verdict
A well-matched choice for dry winter bedrooms. Confirm the model it fits before ordering.
Where to buy
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