Clearing the Air: Air-O-Swiss & Venta Air Washers

by Michael Fallarino

Now is a very good time to think about air quality. The cosmic treadmill has powered down for system maintenance, and many of us have more time to reflect. Why don't we use this time wisely and thoughtfully to design our way into where we want to be in five or ten years as the supply chains of smart, human-friendly building materials and the fixtures that we place in our living environments comes of age?  

When it comes to the broad range of topics that can be discussed when we speak about buildings as living environments, the one which has always been at the top of my list is indoor air quality (IAQ). My opinion is that IAQ, despite a nominal amount of airplay, is still underrepresented.

Over the course of the past month or so, I've been witness to the death of an uncle and a friend, both seniors, who struggled with lung function and ended up in ICUs before expiring. And on my current job, which happens to be in an old craftsman home with a forced hot air system, the topic of IAQ and optimal relative humidity (RH) arose. The discussion was triggered partly by the home owner's “need” to keep the grand pianos in his studio at an optimal level of RH. These folks had a humidification system installed on their boiler with an adjustable RH function which they had dialed in to 40 – 45% RH. But what was the reality? I brought my meters in to do an empirical test. They tested out at between 26 and 29% RH. And that's what it felt like to me.

Perhaps it's due to my holistic medical training, but I feel that our living spaces should be monitored and optimized for RH when HVAC or other circumstances would force an unconditioned living space into an RH of below 40%. After all, we are mostly water and our hydration level interacts directly with our immune system and our vital force. I believe that optimal RH levels are especially important for senior citizens.

In my quest for well designed humidification devices by manufacturers who take humidification and IAQ seriously, a pair of European companies have come into focus, and I field tested a device by each company.

Air washer as a concept

The overwhelming majority of humidification devices function either by generating an ultrasonic mist or by drawing air though some type of filter media that needs to be replaced regularly. Although humidifiers with replaceable filter media can assist in cleansing the air, air washers are functionally designed to be air purifiers and humidifiers in one.

The operative principle is intriguing and ingeniously simple. A fan draws room air downward into the chamber. Inside the chamber, stacks of plastic discs are rotating through a hopper of water. The airborne particulate matter that was drawn in is collected by the disc stacks and subsequently rinsed off as the stacks rotate through the water in the base of the unit, and it precipitates to the base of the hopper. The hydrophilic stacks which have become wetted by rotating through water, rotate up into the air inside the chamber. A secondary air flow inside the chamber directs the cleansed and humidified air out of the sides of the device.


Air-O-Swiss is a brand identity of Swiss manufacturer Plaston AG. I field tested the Air-O-Swiss 2055D, their best selling air washer. This unit is designed to be used in rooms up to 750 square feet. The 2055D is truly a pretty piece of design work, and it's obvious the engineers who crafted it thought through its form and function intensely. Everything from its overall shape, beautiful side-mounted programmable digital hygrometer, removable and nesting one gallon water tank, and internal fragrance receptacle smacks of a very human-centric design. The 2055D also makes use of a very clever Ionic Silver Stick® as its anti-microbial method. The small replaceable stick ($30), which lasts about a year, projects into the water and uses the anti-microbial properties of silver to discourage bacteria growth in the hopper.

The 2055D has two fan speeds and its stated maximum output is 3.25 gallons in 24 hours. In use, its water deployment was on the conservative side, even with an ambient room RH in the 35 to 45 per cent range. It seems ideally suited for the upstairs of a house, especially bedroom areas.


German humidification technology manufacturer Venta markets four sizes of airwashers, with the maximum size rated to condition 2800 square feet. I field tested their LW44 model, which is rated to condition up to 720 square feet and dispense up to three gallons per day. This unit has three fan speeds (rated at 32, 37, and 42 dBA).

Simplicity of form in the fulfillment of function is obviously Venta's operative principle with its air washers. They are essentially a cube with grillwork which houses rotating disc stacks and a fan. Part of the genius of these units lies in the wafer-thin nature of the discs: the LW44 has four sets of disc gangs seven inches in diameter, with 22 discs to a gang. This creates a surface area of 45 square feet which is rotating through the hopper, (which holds three gallons) and this unit had little trouble dispensing a full hopper over the course of a 24 hour period.

Filling the unit is as simple as lifting the fan assembly off the hopper (which automatically stops the fan) and dumping more water into the base (replacing the fan assembly restarts the unit). Poor placement of the top, hard water, slow fan speeds, and low water levels can conspire to create a slight rattling sound with the LW44, which is otherwise a very quiet machine.


In my opinion, the topic of humidifying dry indoor air is an under-investigated aspect of IAQ. The optimal humidification of indoor air, which should be in the 40 to 60% range, carries important multidimensional benefits to human health, influences the furnishings and fixtures in our interior spaces, including wood, electronics, and more; and it can affect the efficiency of heating systems.

The dual function of the Air-O-Swiss and Venta air washer technology can be felt and observed (you can pour the filtered water into a clear glass to observe the mass of collected particles; yuk!). By way of comparison, the Venta seemed to be a potentially quieter, more effective unit, but it lacks many of the design conveniences of the Air-O-Swiss. The Air-O-Swiss 2055D lists for $350 and the Venta LW44 lists for $400. Warranties on both units are a generous 10 years. A case could be made for either of these units — or their brethren – depending on personal proclivities and where you plan to place them.

For more info, visit and Plaston's Air-O-Swiss site in particular has well-developed educational resources about IAQ as it relates to RH and humidification.

Mike Fallarino is a contractor in the Albany, New York, area. He can be contacted at


Archived Content:
Collaborative Efforts 9-10/2009

Archived Content:
The Case for Sill Pans

Archived Content:
The Greening of Home Electronics

Archived Content:
Moisture Meters 2

Archived Content:
Panasonic's IAQ initiatives

Get inside info on top green building products

e-newsletter today!


GBPN Newsletter





Dealer Links:

Amicus Green

Atlas Lumber

Austin Lumber Co.

Alternative Bldg Center

Bingham Lumber

Colt Industries

Dean Hardwoods

Ecohome Improvement

g Green Design

Green Design Center

Mwanzi Supply

Sustainable NW Wood

Links we like:

Sippican Cottage

Greenbuild Expo


© Copyright 2013,
Green Building Product News
Re-publication or re-use without
specific permission is prohibited