I live in a studio apartment that measures somewhere between 500 to 600 square feet. My heating and cooling is derived from one very long vent that sits about a foot and a half above the floor. I use both humidifier units along the vent, but to cover it completely I would probably need four of them. Given that my setup and the size of my apartment is not ideal, this review will focus more on the product than on how effective it is.
It's not apparent from the pictures, but the water-absorbant material is actually foam that isn't so different than the types found in packing materials. This is a bit surprising, since this material isn't as water-absorbant as a sponge. In fact, if the material is dry and you attempt to water the humidifier from above, the water will simply sit on top of the foam and will not penetrate it. I rehydrate it at a sink. The company's instructions suggest squeezing the foam while under running water so as to maximize the amount of water absorbed. It probably helps, but the foam doesn't seem to take up a whole lot of water even then. Unless you allow it to sit for a few minutes, you can also expect to drip some water in the process of moving from the sink to the vent.
One could argue that the choice of foam over traditional sponge material is for airflow purposes. However, even with my single vent (which pushes air with more force than a standard vent system found in houses), the air is forced around the humidifier and does not go through it. This isn't a bad thing for heating systems (since hot air rises anyway), but isn't optimal for air conditioning. Granted, most people will probably use this for winter, but all in all it seems as if the choice to use foam over a different material was likely cost-based.
I had a bad experience with the construction that required some work on my part. Each humidifier has six "feet" that raise it above the vent so that it does not obstruct airflow. Each foot is attached to the main frame by a nut and bolt. When I unpacked my units, many of the feet and their securing nuts were loose in the bag, and many of the feet that remained on the unit had nuts that were nowhere near fully tightened. No tools are shipped with the product, and none of my own tools were small enough to do the job. I ended up using tweezers to thread the nuts along their bolts and affix the feet to the units. I couldn't get them very tight, but it gets the job done a job I should not have had to do. The difficulty (and lack of tools) with getting the feet on and off also makes it clear that the foam was not intended to be removed from the casing for soaking.
Being unable to remove the foam leads to another complaint. While the units look pleasing enough, after two or three rehydrations I noticed that one of the bolts is showing signs of rusting. It's one out of 12 (between two units), but it's clear that it can only get worse from here. The white plastic surrounding the bolts will become a discolored yellow-brown. As the saying goes, "you get what you pay for" it's just another thing to consider.
As far as effectiveness goes, I can't really comment. As I mentioned before my setup is probably not optimal; all the same, it doesn't seem to be making a big difference. The foam does dry out over time, meaning that the air in my apartment is being humidified. It's questionable as to whether it's much more effective than setting out bowls of water and waiting for the water to evaporate from them, though.
In summary, it's a cheap product that doesn't consume electricity to use, but is a bit of a pain to rehydrate. If you have a small room and/or only need slightly more humidity it might be worth trying, but otherwise it doesn't seem worth it. It seems to me that you could make one of these yourself by propping up a wet towel or sponge an inch or so above a vent in fact, I may open up the casing on these humidifiers and replace the foam with sponges.
It works...a little bit. It covers the vent and the air pressure from the vent doesn't get through the product very well.
Buy Set of 2 Portable Heating Vent Register Humidifiers Now
This product has been wonderful in helping to maintain my new air washer. It is easy to mix and helps with the mineral heavy water in my building. I've been able to bypass distilled water since I got this. I do periodically use filtered water anyway (mostly when I just cleaned). As labeled, I use this in a evaporative air washer.
