Frequently asked questions

FAQ regarding our products and dehumidification.

Did you know that the average relative humidity in Sweden is 85% in January and 75% in July, according to SMHI? The threshold for general corrosion (rust) occurs at 60% relative humidity.

Therefore, air ventilated into buildings should either be heated or dehumidified!

Webinar: how moisture works!

Moisture challenges – frequently asked questions about moisture management

Watch the video on how to read a Mollier diagram.

The energy efficiency of a dehumidifier is measured by the energy required to extract one kilo of water from the air in the climate where it will operate.

Product datasheets typically outline the dehumidifier's capacity at various temperatures and moisture levels, expressed as relative humidity [%RH]. The capacity is specified in kilograms of water per hour. Multiplying this figure by the power consumption of the dehumidifier yields the operating cost for dehumidification.

It is crucial to use the correct temperature and humidity levels when making comparisons!
Especially if you also intend to save energy by lowering the ambient temperature in the facility.

An optimal humidity level in most facilities is below 60% RH, which prevents mold and corrosion. All conventional technologies require more energy at lower temperatures. Airwatergreen's warm condensation technology is the only solution entirely independent of the operating climate of the dehumidifier.
With the FLEX series, extracting 1 kilogram of water from the air consumes only 2 kWh according to tests by the SP Technical Research Institute of Sweden, while the REX series consumes approximately 1.5 kWh per kilogram of water.

See the chart from the SP Technical Research Institute of Sweden (RISE)
If you need assistance with moisture calculations or a life cycle cost analysis for your upcoming dehumidifier acquisition, please email us at info@airwatergreen.com

The critical factor for corrosion to occur is the dew point of the pipe. If the pipe is colder than the surrounding air, the dew point is lower at or on the pipe surface, causing moisture in the air to condense on the pipe, resulting in corrosion. This is analogous to a cold beverage can on a warm summer day.

We can calculate the dew point and configure the dehumidifier to use an external sensor that measures the exact temperature of the pipe, thereby controlling the unit to maintain the precise humidity level required to prevent condensation.

Dew point chart:

Yes, we can conduct a moisture assessment using sensor technology. We place these moisture sensors in selected locations for a couple of weeks, allowing us to present an evaluation of humidity trends over time based on the collected data.

Based on this data, we can advise on the appropriate next steps tailored to your specific moisture challenges, utilizing a proprietary calculation methodology we have developed.

We provide the equipment and can assist with installation, including installing a drainage pump if necessary to evacuate water from subsurface spaces lacking a floor drain or sewage connection.

No, you can lower the temperature. Our technology is equally efficient in cold air as it is in warm air!

Reducing heating has proven highly successful in churches and intermittently used buildings. Lower the temperature in the building, and our FLEX or REX units will maintain the relative humidity at the correct level. This enables significant energy savings through both reduced heating costs and enhanced dehumidifier efficiency.

For example, a church property can reduce its energy consumption by over 80%, yielding an investment payback period of just over 1 year.

Below is a Mollier diagram description illustrating what occurs when the temperature changes without moisture being removed from the air.

  1. The temperature is reduced from 20°C to 11°C (blue arrow), causing the relative humidity to rise from 50% RH to nearly 100% RH. If left unaddressed, this will result in corrosion and mold growth.
  2. The extraction of moisture from the air (brown arrow) at a constant temperature restores the level to 50% RH. Slightly less than 5g of water per cubic meter of air needs to be removed.

Material dehumidification can be divided into three phases.

  1. Water is drawn capillarily from the interior of the material up to the surface.
  2. Transport occurs via capillary action in the liquid phase within the small pores and via vapor phase (diffusion) within the larger pores.
  3. Transport occurs exclusively in the vapor phase. The rate is governed by the difference in vapor concentration between the material and the surrounding air.

Step 1 is heavily dependent on the type of material to be dehumidified. The stage that can typically be influenced most is step 3—ensuring that moisture leaves the surface of the material and transfers into the air. Heating the material containing the moisture will accelerate the process.

The simplest approach is usually to ensure that the air is kept dry at all times, preferably at a low relative humidity (RH). This results in a greater vapor pressure differential and faster drying!

See the graph on the right, which illustrates the differences in vapor pressure at various RH levels when the air and material are at the same temperature.

In other words, lowering the RH in the air to 40% accelerates the drying process because the vapor pressure differential increases (left axis). This results in faster drying!

Air heating

The graph on the right illustrates what happens when only the air is heated. At slightly higher relative humidity levels, the vapor pressure differential can become negative.
This causes the moisture in the air to condense on the wall instead.

Consequently, unless you are careful, this can lead to humidification rather than dehumidification!

Typical questions about dehumidification

Warm condensation is a patented technology where moisture is first captured in a desiccant, which is then dried out in a closed, heated condensation process.

Water and dry air are discharged. No connections other than a water drainage line are required, making installation straightforward and ensuring that all supplied energy remains within the room rather than being ventilated outside.

Airwatergreen's technology enables the dehumidifier to operate with equal efficiency in all climates regardless of temperature, allowing it to dehumidify even at sub-zero temperatures. The methodology of warm condensation is described in detail in this report Modeling a novel sorption dehumidification method – written by Per D

Maintaining warm air can hardly be considered a dehumidification method, as no moisture is actually removed from the air.

However, heating the air will lower the relative humidity (RH) level because warm air can "hold" more moisture than cold air. No water is removed from the building's air, which means heating must be maintained continuously to prevent excessively high relative humidity.

A study conducted at Uppsala University shows that maintaining the same relative humidity using heating is approximately 5 times more energy-intensive than using dehumidification. If you wish to read the study, it is available for download here.

Ventilation should not be considered dehumidification, as no water is removed from the air. This method depends entirely on the outdoor climate and the ambient temperature relative to the temperature of the space experiencing moisture challenges. You might actually be introducing more moisture into the building rather than removing it.

Ventilation is frequently used because it is perceived as an inexpensive and simple solution. However, ventilation can create more problems than it solves. A typical scenario we often observe is when ventilation brings warm, humid air into a cool crawl space during the summer—not a suitable method!

Water droplets form on a cold surface—this is a well-known phenomenon. It occurs because cold air cannot hold the same amount of moisture as warm air. This fact can be utilized for dehumidification because it actually extracts water from the air. At the same time, however, this very phenomenon is the root cause of corrosion and mold growth in buildings and structures!

To use cold condensation as a dehumidification method, the air must be reheated after condensation occurs. Otherwise, the relative humidity will remain at the same high level.

This means that this method can only be used at certain temperatures to avoid ice buildup on the cold surface.

Sorption dehumidification is considered the modern dehumidification method, developed in Sweden in the 1950s to dehumidify under Swedish climatic conditions. Over the years, this method has been utilized in numerous installations.

The method involves capturing moisture from the air in a slowly rotating wheel, and subsequently drying the wheel in a second step using warm air. The warm air absorbs the moisture, which is then typically discharged through a core drilled hole in the wall.

Installation can easily become costly depending on how the air ducting is routed, and energy is lost through the penetration in the wall.

Questions about the products – FLEX, REX, BLACKBOX, and NEXT-S

With the new Temp Guard feature in Flex, you can ensure that the space remains frost-free using the integrated element as a heat source.

Read more here about Temp Guard.

To be completely certain of our claims, we had the Swedish National Testing and Research Institute (now RISE) test our dehumidifier and compare it with a traditional sorption dehumidifier.

The results of that test show that our dehumidifiers consume half as much energy to extract the same amount of water.

Would you like to read the full test? Click here.

The water extracted from the air is discharged from the outlet on the side of the dehumidifier. A hose can easily be connected so that the water can be directed to a drain or a tank.

If no drain is available, specially designed containers are available. A standalone model as well as a container that also functions as a wheeled cart to easily relocate the FLEX if necessary.

The FLEX is tilted to create self-drainage. Water flows out of the unit without the need for a pump. This reduces energy consumption and minimizes the number of moving parts.

If the green light changes from a steady glow to flashing, the dehumidifier requires service.

Instructions can be found in the manual under Chapter 6 – Service. Alternatively, contact our support at support@airwatergreen.com.

We recommend replacing the granulate once a year to maintain the dehumidifier's full capacity. Suitable granulate is included in our Filter Kit. This is delivered as part of our Service Agreement, or it can be ordered directly from us.

Yes, absolutely.

The granulate required for replacement is supplied in a package called a Filterkit. You can order Filterkits directly from us. Instructions can be found in the manual (available for download on the FLEX and REX download page).
Or visit our YouTube channel to watch the video on how to refill the granulate yourself.

Material dehumidification can be divided into three phases.

  1. Water is drawn capillarily from the interior of the material up to the surface.
  2. Transport occurs via capillary action in the liquid phase within the small pores and via vapor phase (diffusion) within the larger pores.
  3. Transport occurs exclusively in the vapor phase. The rate is governed by the difference in vapor concentration between the material and the surrounding air.

Step 1 is heavily dependent on the type of material to be dehumidified. The stage that can typically be influenced most is step 3—ensuring that moisture leaves the surface of the material and transfers into the air. Heating the material containing the moisture will accelerate the process.

The simplest approach is usually to ensure that the air is kept dry at all times, preferably at a low relative humidity (RH). This results in a greater vapor pressure differential and faster drying!

See the graph on the right, which illustrates the differences in vapor pressure at various RH levels when the air and material are at the same temperature.

In other words, lowering the RH in the air to 40% accelerates the drying process because the vapor pressure differential increases (left axis). This results in faster drying!

Air heating

The graph on the right illustrates what happens when only the air is heated. At slightly higher relative humidity levels, the vapor pressure differential can become negative.
This causes the moisture in the air to condense on the wall instead.

Consequently, unless you are careful, this can lead to humidification rather than dehumidification!

The activated carbon is easily replaced when it is no longer capable of absorbing hydrogen sulfide. Regular replacement is included when entering into a service agreement.
The Airwatergreen Blackbox Filterkit Activated Carbon contains the required amount for one Blackbox.

NEXT-S consists of two modules, of which only the absorber itself is active for the majority of the operating time. During absorption, only one air fan and one desiccant pump consume energy.

Regeneration is initiated only when necessary – and energy consumption is independent of ambient air temperature and humidity.

Unlike traditional condensation technology, NEXT-S maintains high efficiency even at low temperatures. NEXT-S is optimized to deliver excellent performance at the temperatures (2 – 12°C) typical of the food industry and cold storage facilities.
(Naturally, it still functions exceptionally well at normal room temperature).

The unique feature of AWG's technology (CVP = Controlled Vapor Pressure) is that it functions exceptionally well as a completely standalone installation. You need a 32A fuse and access to a suitable drain. Nothing more!

AWG offers various levels of service agreements. Typically, we include an annual service performed by AWG personnel. In dusty environments, the external air filter may need frequent replacement – this can easily be done by the customer's own staff in a few minutes.

NEXT is based on a modern, powerful PLC that can also be upgraded remotely if needed. We offer full connectivity to AWG's cloud service, which facilitates both monitoring and preventive maintenance. External sensors can easily be connected to optimize climate control.

AWG has extensive experience delivering to both the water and food industries, meeting the specific cybersecurity requirements inherent to these sectors.

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